U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service

 

 
'' 

 
''ALGAE IN
WATER SUPPLIES

An Illustrated Manual on the Identification, Significance, and

Control of Algae in Water Supplies

C. MERVIN PALMER

WITH AN INTRODUCTION BY CLARENCE M. TARZWELL

ILLUSTRATIONS IN COLOR BY HAROLD J. WALTER

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

PUBLIC HEALTH SERVICE

Bureau of State Services » Division of Water Pollution Control

Robert A. Taft Sanitary Engineering Center

CINCINNATI, OHIO
''Public Health Service Publication No. 657
1959

 

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington 25, D.C. - - - - - - - -

Price $1
''FOREWORD reac

LIBRARY

This manual has been prepared for water analysts and others who deal with the many
problems and effects associated with the presetice of algae in water supplies. The need of
an up-to-date concise account of the algae important in water supplies has been felt for some
time, and the large demand for copies of a preliminary article’ on the subject, published
in June 1955, confirms this interest.

In the present state of our knowledge and with increasing activities in this field, any
manual on algae can be only a broad forerunner of more specific handbooks on various phases
of the subject. Workers will now have at least a concise general account, the absence of which
has doubtless prevented many from making adequate analyses of the aquatic organisms belong-
ing to this important group of plants.

MARK D. HOLLIS,

Assistant Surgeon General
Chief Engineer, PHS.

1 Public Works, vol. 86 no. 6 pp. 107-120 (June 1955).

Ill

967
'' 

 

 

 

 
''PREFACE

The available literature on algae has tended to be of two extreme types. Several recent
treatises contain extensive scientific descriptions of algae of particular areas or are monographs
of a single genus or group. These are excellent for academic studies and for encyclopedic and
background references in applied phycology. At the other extreme are a considerable number
of brief papers concerned with certain phases of problems, enumeration, or treatment of algae
in water supplies. None of these are sufficient for use as guides in dealing with the recogni-
tion of the more important kinds of algae together with the interpretation and use of such
information in the control or utilization of algae present in water supplies.

This manual has been prepared to help fill the need for more complete information on
those algae important in water supplies and particularly to include a key, illustrations, and
other aids needed for their identification. References to related literature are listed at the
ends of the chapters in which they are cited.

There has also been an expanding interest in developing new industrial procedures where
algae are utilized. This is in addition to various problems which they are responsible for in
water treatment and water use. Together these interests have brought about an increasing
demand for information on the algae which are involved.

The manual omits the many rare or uncommon algae as well as those growing in habitats
other than water supplies. Only a limited amount of information is included on marine and
estuarine algae; the bulk of the manual deals with the fresh-water forms.

It is not possible at present to refer to any single or standard procedure for the recording
and counting of algae and for their control. We can merely point and work in that direction.
With the desire growing for exchange of algological data by water treatment plants, and by
many others concerned with algae, the need for standardized procedures is becoming more
apparent.

In compiling this manual, the aid of many co-workers has been requested and has been
generously given. Some of the work of correcting and critical reading of the manuscript has
been assumed by several members of the staff of the Robert A. Taft Sanitary Engineering
Center. Grateful acknowledgment for this service is given particularly to B. B. Berger, Chief
of the Water Supply and Water Pollution Program, C. M. Tarzwell, Chief Aquatic Biologist,
and R. T. Hyde, Information Officer. Credit for producing the colored illustrations of algae
goes to Harold J. Walter, and for the cover design to Judith A. Walters. All photographs
and line drawings were furnished by the writer except Figure 88 which was obtained from
J. R. Baylis, Engineer of Water Purification, Bureau of Water, Chicago, Illinois. The writer
is indebted to these co-workers and many others for their painstaking cooperation in prepara-
tion of the manual.

C. Mervin Patmer, Jn Charge

Interference Organisms Studies

Water Supply and Water Pollution Program
Robert A. Taft Sanitary Engineering Center
Cincinnati, Ohio
'' 

 

 

 

 

 

 
''eo Cr ee

CONTENTS

Introduction . :

Significance of Algae in Water Bapplies

Identification of Algae . ae

Taste and Odor Algae .

Filter Clogging Algae .

Polluted Water Algae .

Clean Water Algae .

Plankton and Other Surface Water Algae

Algae Attached to Reservoir Walls

Additional Problems Caused by Algae in Water Supplies

. Additional Uses for Algae Found in Water Supplies .
. Procedures for Enumeration of Algae in Water
. Control of Algae

Appendix:

Key to Algae of Importance in Water Supplies
Glossary ee es
Bibliography . :

Genus and Species Tadeo

TABLES

Table

1. Comparison of the four major groups of — in

water supplies

2. Algae in water supplies—a list of the. more im-

portant species . .
Recent changes in names of algae .

Cue

with algae in water .
Filter clogging algae .
Pollution algae .
Clean water algae .
Plankton and other surface water lee
Algae attached to reservoir walls

See es ee

fh foe

supplies . :
12. Other uses for algae in intee eo
13. Relative toxicity of copper sulfate to algae

Taste and odor algae, representative species
Odors, tastes, and touch sensations associated

Additional oe caused by algae in water

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VII
''ILLUSTRATIONS

Color Plate Page
1. Taste and odor algae . 26
2. Filter clogging algae . 28
3. Pollution algae . 30
4. Clean water algae . ; epee 32
5. Plankton and other surface maces alee ee 34
6. Algae growing on reservoir walls. ..... . 36
Figure Page Figure
1. Mats of algae floating on the surface of water . 6 27. Thick walled zygospores formed during sexual
2. Water net, Hydrodictyon reticulatum . 9 reproduction in Zygnema norman .
3. Spirogyra ellipsospora : 9 28. True branching in the blue-green alga, Nosto:
4. Spirogyra varians . : : 9 chopsis lobatus ‘
5. A blue-green alga, Beviiacies wrangelii : 9 29. Ulothrix zonata, whose filament anid cares
6. A green alga, Pediastrum boryanum . 9 in spore production. Its two strains react
7. A desmid, Cylindrocystis brebissonii . : 9 differently to pollution .
8. Anacystis cyanea (formerly Microcystis aeru- 30. Oscillatoria limosa .
ginosa) . 9 31. Oscillatoria tenuis .
9. Agmenellum gudiiiduplicatum ines Aoniemnes 32. Oscillatoria princeps .
pedia glauca) . 9 33. Phormidium uncinatum
10. Phytoconis Botnyotdes Saemgeely Proleaccnia viri- 34. Calothrix parietina is attached to las at steintas in
dis) . Ets 9 running water
1. Haenatoodscun states (formerly Sphacreta die 35. Ankistrodesmus falcatus ;
custris) 9 36. A surface blanket of filamentous ‘eae.
12. Colonies of Gadotindes: fora: in Ocinpstte novae- 37. Gloeotrichia natans
semliae ; 9 38. Plankton diatoms showing ‘distnioties inheiaes bt
13. A simple filament, Dae onic : 9 cells and colonies .
14. Threads are grouped into erect cones in Symploca 39. Vaucheria geminata .
muralis 9 40. Vaucheria sessilis .
15. Filament with shrandiate branching s in Marsters: 41. Pithophora oedogonia
nion strictissimum . 11 42. Schizomeris leibleinii
16. A branching, tubular, nonseptate alg, Botrydium 43. Stigonema hormoides . con
granulatum . 11 44. Tetraspora. Portion of colony ‘diowite: alle
17. Cells embedded in a gelatinous tube’ in ideas grouped in fours. Pseudocilia are barely vis-
Soetidus 11 ible on a few of the cells .
18. Mature and young paniious of Coipar pogon 45. Closterium lunula, a desmid
coeruleus . 11 46. Lyngbya majuscula, showing empty shesthes ex-
19. Microcoleus paludosus, ehoaliie a enie: suread tending between threads of cells . :
and a group of threads surrounded by a 47. Nodularia spumigena, the first blue-green es
sheath, under high and low magnification 16 reported as toxic
20. Scenedesmus quadricauda, showing spine-like ex- 48. Coccochloris peniocystis .
tensions on the terminal cells . 16 40. ‘Trachelomonae Manda
21. Lateral flagella in Merotrichia capitata . : 16 : .
22. Anterior flagella on cells of Pleodorina “illinoi- 50. Scenedesmus obliquus
sensis . 16 51. Pediastrum duples .
23. Posterior and lateral + views of anterior ‘flagella 52. Chlorogonium euchlorum .
on Gonium sociale . ; 16 53. Nannoplankton counting slide
24. Two spore-producing cells on filaments of Eien 54. Algal plankton record . ote : :
tepohlia aurea . : 16 55. Experimental testing of a potential dened:
25. Enlarged terminal vpuodsenien sales on eimai (a) Applying the oS to a blanket of
of Audouinella violacea . 16 algae .
26. Terminal cells specialized for sexual reproduction (b) Results of the test: "Blanket ‘of algae has
in Vaucheria arechavaletae 16 disappeared . wie ee Geren

VIII

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''Algae in Water Supplies
'' 

 

 

 

 

 

 
''CHAPTER 1

INTRODUCTION

THE GREAT INCREASE in population and the rapid
development of agriculture and industry have caused a phe-
nomenal increase in our use of water in recent years and have
brought about many difficult problems in the procurement of
suitable water supplies. As the country continues to grow
and develop, these problems will become more widespread
and complex. In the past, most people of the United States
have taken their water supply for granted, assuming that it
is something which is always available. This may be due in
part to our efficient water distribution systems. The present
generation has become so accustomed to an abundant, safe
and potable water supply at the mere turning of a tap, that
its value and importance are not realized. It is certain, how-
ever, that the people of this country will increasingly recog-
nize that suitable water supplies are exhaustible and that
water costs whatever you have to pay to get it.

In the clearing and development of the country, especially
the eastern portion, changes in the ground cover and the
surface soil have greatly altered surface runoff and ground
seepage. Deforestation, fires, overgrazing, agricultural use,
and drainage have increased surface runoff and erosion and
reduced soil seepage in many areas. It has been estimated by
some authorities that, during the past 50 years, the water
table in the eastern half of the country has been lowered
about 60 feet. The lowering of the water table, coupled with
increased use of ground water, has created severe shortages
of ground water in many areas.

As population and industrial demands increase and ground
water supplies become inadequate, more and more cities and
villages are turning to lakes, streams, or reservoirs for their
water supplies. This change from ground to surface source
of supply has created many new problems for those engaged
in the procurement and treatment of water for domestic and
other uses. Ground waters are essentially free of organisms
which may cause nuisance problems, whereas all surface
waters contain many organisms which may complicate the
provision of a potable water. Some problems are odor and
taste, the clogging of filters, growths in pipes, cooling towers
and on reservoir walls, surface water mats or blooms, infesta-
tions in finished waters, and toxicity.

Present methods of waste disposal are intensifying the
nuisance organism problems in water supplies. The number
and kinds of algae and other organisms which grow in sur-
face waters depend on environmental conditions. Fertiliz-
ing materials such as sewage and organic wastes from milk
plants, canneries, slaughter houses, paper mills, starch fac-
tories, and fish processing plants greatly increase the pro-
ductivity of the waters and their crops of algae and other
plankton organisms, many of which produce problems when
they become abundant. It is apparent, therefore, that nui-

sance organism problems will become more widespread and
severe as our growing urban populations and industry con-
tinue to discharge their wastes into streams.

In muddy streams such as the Missouri, turbidity limits
light penetration sufficiently so that few problems occur from
algal growth. When impoundments are built in such a
stream they create settling basins in which the water clears
and algal growths develop, producing tastes and odors or
other nuisance conditions. The extensive impoundment pro-
gram which has been underway for over 20 years can create
many water supply problems which did not exist previously
in these waters.

Pool size, shape, depth, amount of shore line, extent of
shoal areas, character of the bottom, physiography and soils
of the watershed, amount and rate of precipitation, sunlight,
and the quality of the water are all factors influencing the
growth of algae in a reservoir. A narrow deep reservoir
having no shoal areas, a minimum of shore line, little wind
mixing, and unproductive watershed, and soft water low in
dissolved solids will have less algae than a wide, shallow,
irregular reservoir located in an area of rich soil where the
incoming water is rich in dissolved materials and there is
complete wind mixing. In many areas the best reservoir
sites have already been utilized. New reservoirs will have
to be built in less favorable sites where productivity of algae
will be greater. In the great plains area and in several other
parts of the country, reservoir sites for water storage are
usually wide and shallow and favorable for the development
of plankton growths.

In view of these conditions problems due to nuisance
organisms will become more widespread and of greater im-
portance. In several areas they are now the number one
problem of water works operators.

The importance of the nuisance organism problem was
recognized when aquatic biological investigations were acti-
vated in the Public Health Service water research labora-
tories at Cincinnati. A unit was set up in 1950 to study
organisms that create problems in the provision of a potable
water supply and to develop methods for their control or
elimination. Because tastes and odors seemed to be of out-
standing importance, work on this phase of the problem has
been stressed. Work has been done, however, on algicides
and several other phases of the problem. Although it has
been possible to secure unialgal cultures of a large number of
species, the growing of algae in pure culture has been diffi-
cult. Methods have yet to be developed for the growth in
pure culture of most of the algal species believed to produce
odors or tastes in water supplies. Some species do not grow
readily in the absence of bacteria, indicating that bacteria
may produce some material needed by the algae. The addi-

3
''4 ALGAE IN WATER SUPPLIES

 

tion of vitamins and certain organic materials has provided
needed nutrients in some instances.

Until recently our knowledge of taste and odor algae was
circumstantial and rather loose. When odors or tastes de-
velop in water supplies, they are commonly blamed on the
most abundant forms, which may or may not be the cause. Of
course, when the same alga is found in a series of taste and
odor outbreaks, the circumstantial evidence becomes quite
strong. However, since most forms alleged to cause odor or
taste are usually reported as the genus, the information is
rather loose, in that some of the genera may contain 100 or
more species.

When the nuisance organism work was first undertaken at
the Sanitary Engineering Center, it was considered essential
to work only with species and to grow them in pure culture
free from bacteria, molds, yeasts, actinomycetes, and other
organisms, in order to determine definitely whether a par-
ticular alga caused a taste or odor. The development. of
methods for the culturing of algae required considerable
time and effort. Therefore, it was decided to go beyond the
determination of odor or taste production, and studies have
been made to improve methods of using existing algicides
and to find better or more specific materials. Specific algi-
cides would be of considerable economic benefit, as smaller
amounts of material could be used to control only undesirable
forms without affecting the others. This is very important
from the standpoint of fisheries management, as algae consti-
tute much of the base of the food pyramid on which all the
higher forms of aquatic life depend. Further, such a pro-
cedure gives a form of biological control. The application
of very toxic materials in large dosages which kill practically
all the algae is undesirable. When much of the population is
destroyed, the weed species come back first, and, since there
is little competition, in great abundance. If selective algi-
cides can be discovered, their use will control the problem
species, while the desirable forms can increase so that the
undesirable species are less likely to come back in large
numbers.

Algicidal and/or biological controls are feasible in lakes,
small streams, or reservoirs where most of the water is used.
They are economically unsuited to large lakes or rivers where
only a portion of the water is used by the water plant. In
such situations some other method of treatment must be pro-
vided in the water plant. It is believed that materials caus-
ing odor or taste are present in very small amounts. If the
taste and odor materials produced by so-called nuisance or-
ganisms are known, it may be possible to treat or change
them by additives to render them innocuous. This could
probably be done in the coagulation process. Investigations
are underway to recover, isolate, and identify odoriferous
materials produced by algae and other organisms in water
supplies.

Studies of attempts to control algal problems in water
works have revealed hit-or-miss procedures, little coordina-

tion of effort, and only occasional systematic recording of
essential data. The great majority of water works are not
staffed for making studies to determine the cause of their
trouble, to identify the organisms responsible, or to detect
their development before the undesirable materials actually
get into the water system in quantity. The value of con-
tinued surveillance of algal populations has been proven by
studies in several of the larger water plants. There has been
a need for some time for a planned and uniform approach to
this problem, usable by more plants and placing information
in an understandable and useful form into the hands of those
who need it. This manual is an attempt to meet this need
by water plant operators in appraisal of nuisance organism
problems and furnishing information for remedying some
difficulties.

It is realized that very few operators or members of their
staff have had training in aquatic biology or in the identifica-
tion of algae. However, if growths of algae are to be de-
tected and controlled before they cause trouble, continued
surveillance of plankton populations and identification of ,
the organisms are essential. This manual presents a simpli-
fied key limited to species of importance in water supplies.
All terms and structures used in this key are defined and
illustrated. The most important species of algae are illus-
trated in three-dimensional drawings in color which show
both external and internal structures. The drawings are
based on actual specimens and on descriptions from a large
number of texts. It is believed that with these drawings
and the key any operator who applies himself diligently will
be able to identify at least the most important forms. As
experience is gained he should become able to detect the
development of troublesome algae so that control measures
can. be initiated before real trouble develops. In addition to
the key and plates, the manual deals with the ecology and
life history of algae and presents concise and pertinent in-
formation on filter clogging and mat-forming algae, attached
forms, algicides, and algal control.

Eventually this manual may become useful in at least
two other ways in meeting important problems. If algicides
specific for certain species or groups of species can be found,
operators can identify the organisms causing the trouble and,
from a listing of specific algicides, determine the particular
material which should be used for control. Further, if the
source and substance of materials produced by algae which
cause odors or tastes can be identified, the operator will be
helped to determine what materials and methods should be
used in the water plant to render innocuous the algal
metabolites causing the trouble.

CLARENCE M. TarzweE tt,
Chief of Aquatic Biology
Robert A. Taft Sanitary
Engineering Center
Cincinnati, Ohio
''CHAPTER II

SIGNIFICANCE OF ALGAE IN WATER SUPPLIES

ALGAE are common and normal inhabitants of surface
waters and are encountered in every water supply that is
exposed to sunlight. While a few of the algae are found in
soil and on surfaces exposed to air, the great majority of
them are truly aquatic and grow submerged in the waters of
ponds, lakes, reservoirs, streams, and oceans. By operators
of water treatment plants the algae are best known for their
ability to produce odors and tastes and to clog sand filters.
In addition, they have come to be recognized as important
in the water supply in many other ways, including their ca-
pacity for modifying the pH, alkalinity, color, turbidity,
and lately the radioactivity of the water. Some are un-
doubtedly the most troublesome of the various types of nui-
sance organisms, but others can actually be put to good use
in improving a water supply.

One of the principal reasons for the importance of algae
is their alibity to give rise to very large quantities of or-
ganic matter in the water. It has been estimated, for ex-
ample, that more than 130 tons of algae per day flow into
Fox River, Wis., from Lake Winnebago (1): The volume
of plankton algae in the Scioto River, Ohio, has reached a
maximum of more than 8,000 p.p.m. (2). Algal counts for
Lake Michigan at Chicago have at times been over 4,000
organisms per ml. (3), and the White River in Indiana has
records of counts exceeding 100,000 algae per ml. (4). Such
large quantities of algal material can always be counted on
to cause serious difficulties in water treatment plants.

Small numbers of certain particular kinds of algae may
also be troublesome. The diatoms 7 abellaria, Synedra, and
Melosiva will almost invariably reduce the length of filter
runs. The brown flagellate, Synura, even in small numbers,
is a notorious taste and odor producer. Comparatively low
concentrations of most of the algae, however, are often an
asset rather than a liability in raw waters.

Unattached, visible, and sometimes extensive accumula-
tions of algae at or near the surface of the water are desig-
nated as “blooms” or “mats” (fig. 1) or “blankets,” the last
two terms generally being applied when the algae are in the
form of threads or filaments. Many of the algae attached
to submerged rock, wood, soil, or the surface of trickling
filters may form continuous carpets of growth. When the
water becomes turbulent, fragments of the algal carpet may
become detached and be carried away. These massive
growths of algae can be troublesome in clogging screens, in
the production of slime, and as a source of tastes and odors
particularly if anaerobic decomposition occurs. The blooms
and surface mats can be the cause for complaints by persons
using the body of water for recreational purposes. They also
may be one cause of fish kills by acting as a barrier to the
penetration of oxygen into water under the algae. Algae

that are dispersed and not in blooms or mats normally would
have just the opposite effect.

The algae that collect and grow on the surface of a slow
sand filter as a gelatinous slimy film may be responsible for
graudally reducing the flow through the bed, but they also.
perform a useful service by adding oxygen to the water,
which permits the bacterial decomposition of organic matter
within the filter to remain aerobic. Anaerobic activities in
the sand bed would tend to render the filtrate less palatable.
The slimy mass of algae and other aquatic plants and ani-
mals at the surface of a slow sand filter is called the “filter
skin” and has also been referred to under the German name
of “Schmutzdecke.”

The unattached organisms that are dispersed individually
or in colonies in the water are designated collectively as the
“plankton.” Included are the plankton algae, which consti-
tute most of the “phytoplankton” (meaning plant plankton),
and the planktonic animals or “zooplankton.” When the
water supply comes from a large, deep reservoir or lake, the
planktonic algae are likely to be of much more significance
than the attached or “benthic” algae. Many water treat-
ment plants, therefore, keep records of the plankton but not
of the benthos. In some treatment plants it is a general
practice to apply an algicide to the raw water whenever the
concentration of planktonic algae approaches a count of 500
areal standard units per ml, (5).

All surface waters contain dissolved and suspended ma-
terials which serve as nutrients and support the growth not
only of algae but of many other kinds of aquatic life, num-
bers of which are governed to a great extent by the amounts
and kinds of nutrients available. Some of the aquatic plants
and animals are large, such as the fish, turtles, cattails, and
water lilies, but there are immense populations of small
forms, many of them microscopic in size. The microscopic
organisms in addition to algae include bacteria, actinomy-
cetes, molds or fungi, yeasts, protozoa, rotifers, micro-crus-
tacea, minute worms, and mites. Many of these may play
a major part in affecting the quality of the water and have
to be dealt with in the process of preparing water for do-
mestic and industrial use. The present account deals pri-
marily with the algae but it is obvious that the activities of
one group of organisms are closely associated with activities
of the other organisms present in the same environment.

PHOTOSYNTHESIS

Algae differ from the other groups of small or microscopic
organisms in possessing an internal green pigment called
chlorophyll, sometimes hidden or partially masked by other
pigments, which enables them in the presence of sunlight to

=
''6 ALGAE IN WATER SUPPLIES

 

 

Figure 1.—Mats of algae floating on the surface of water.

combine water and carbon dioxide to form starch or related
substances, and to release oxygen into the water. This
process known as photosynthesis (6) is absent in all typical
bacteria, actinomycetes, fungi, yeasts, protozoa, and crus-
tacea. In general it is not characteristic of animals but is
common to all types of green plants. On the other hand,
respiration is a process carried on by all plants and animals
and the gaseous exchange is the opposite of that in photo-
synthesis; i.e., oxygen is absorbed and carbon dioxide is re-
leased. However, in algae and other green plants the rate of
their photosynthesis is normally faster than their respiration.
These organisms, therefore, release more oxygen than they
use and absorb more carbon dioxide than they release while
animals and other nonphotosynthetic organisms release
sarbon dioxide and absorb oxygen from their environment.
For this reason, the amounts of oxygen and carbon dioxide
in an environment such as water often depend to a large
degree upon the relative rates of photosynthesis and respira-
tion being carried on collectively by the algae, bacteria, and
other organisms in that area.

Some aquatic, pigmented forms containing chlorophyll
are able to swim or crawl, although most of the typical algae
are not capable of self locomotion. Many of these pigmented
swimming forms have whip-like structures called flagella
and have been classified by some workers as protozoan ani-
mals rather than as algae. However, it seems best, in sani-
tary science, to list them as algae (7).

The algae make possible important chemical changes and
metabolic activities in the water through their release of
oxygen during daylight hours. The oxygen is made avail-
able for respiration that is carried on by all types of animals
from fish on down to the smallest forms. It helps to prevent
foul or septic conditions by stimulating the activities of
aerobic rather than anaerobic bacteria. The algae constitute
the primary source for continuous daytime renewal of this
essential element in most bodies of quiet water. Oxygen re-
lease by algae and oxygen uptake by reaeration are the two
primary sources for renewal of oxygen in flowing streams
and turbulent water.

Another important chemical effect of algae is the continu-
ous removal of carbon dioxide from the water during the
daylight hours as a result of photosynthesis. This process
brings about an alteration in the relative amounts of soluble
(unbound) carbonic acid, intermediately soluble (half
bound) bicarbonates, and the nearly insoluble (bound) mono-
‘arbonates, often causing some of the latter to precipitate.
All of this produces a change in the total hardness of the
water. Vigorous algal growths have been known to reduce
the water hardness by as much as one-third.

These changes in carbon dioxide and hardness also tend to
change the pH of the water. The pH will increase as the ©
algae increase their photosynthetic activity during daylight
hours. The pH then decreases at night when the algae are
not carrying on photosynthesis but are releasing carbon di-
''Significance of Algae in

Water Supplies -

 

oxide in respiration. These changes in hardness and in pH
must be taken into account at the water treatment plant since
they may require changes in the dosages of chlorine, alum,
and other chemicals added to the water at the plant .
Corrosive activity of the water is also often increased as a
result of algal growth. This can have far-reaching effects
on the pipes in the distribution system and on many indus-
trial processes where water is in contact with the machinery.
In California, algae attached to the metal walls of sedimen-
tation tanks caused deep pits to be formed in the metal as a
result of the depolarizing action of the oxygen produced by
the algae. Algae in contact with submerged concrete blocks
have caused complete disintegration of the concrete (8).
Increasing attention is now being paid to algae that pro-
duce toxic organic substances causing the death of many
kinds of wild and domestic animals. However, there appear
to be few records of algae that are toxic to humans, although
some have several times been looked upon with suspicion as
the possible cause of certain outbreaks of gastro-intestinal
disorders among persons using a common water supply.
Problems introduced by algae in the providing of suitable
water supplies, together with the utilization of some of these
same organisms in improving the water supplies and in treat-
ment of sewage, clearly indicate a need for more knowledge
of their environmental requirements, life histories, growth,
and nutrition. In order to help in meeting this need, re-
search scientists at a number of laboratories, including the
Robert A. Taft Sanitary Engineering Center of the Public
Health Service in Cincinnati, are studying the various algae
of importance in water and sewage.
Reports have been published for various parts of the con-
tinent which summarize the importance of algae and other
"interference organisms in water supplies. The regions that
have been covered include New England (9), the Chesapeake
area (10), Indiana (11), and Canada (12).

~ 8.

10.

11.

12.

. Plankton populations in Indiana’s White River.

. Comprehensive survey of taste and odor problems.

. Photosynthesis in the algae.

REFERENCES

. Current water pollution investigations and problems in Wisconsin.

K. M. Mackenthun. In Biological Problems in Water Pollu-
tion, ed. by C. M. Tarzwell. Dept. Health, Ed. and Welfare,
Public Health Service, Robt. A. Taft San. Eng. Center, p. 179-
183. 1957.

. A study of pollution and natural purification of the Scioto River.

R. W. Kehr, W. C. Purdy, J. B. Lackey, O. R. Placak, and W. E.
Burns. U.S. Public Health Service, Public Health Bull. 276,
153 p. 1941.

. Quantitative study of the phytoplankton of Lake Michigan at

Evanston, Illinois. K. E. Damann. Butler Univ. Bot. Stud.
5: 27-44. 1941.

J. B. Lackey
and BE. R. Hupp. Jour. Amer. Water Wks. Assn. 48: 1024-1036.
1956.

H. N. Lendall.
Water Wks. Eng. 99: 12387-1238. 1946.

R. W. Krauss. Indust. and Eng.

Chem. 48: 1449-1455. 1956.

. Suggested classification of algae and protozoa in sanitary science.

C. M. Palmer and W. M. Ingram.
27: 11838-1188. 1955.

Biological corrosion of concrete. HE. T. Oborn and EH. C. Higgin-
son. Joint Rept. Field Crops Res. Branch, Agric. Res. Service,
U.S. Dept. Agric., and Bur. Reclamation, U.S. Dept. Interior.
8p. Jan. 1954.

Sewage and Indust. Wastes

. Algae and other interference organisms in New England water

supplies. C. M. Palmer.
72: 27-46. 1958.

Algae and other organisms in waters of the Chesapeake area.
C. M. Palmer. Jour. Amer. Water Wks. Assn. 50: 938-950.
1958.

Algae and other interference organisms in Indiana water supplies.
C. M. Palmer and H. W. Poston. Jour. Amer. Water Wks.
Assn. 48: 1335-1346. 1956.

Survey of water purification practice in Canada. D.H. Matheson
and A. V. Forde. Jour. Amer. Water Wks. Assn. 49: 1522-1530.
1957.

Jour. New England Water Wks. Assn.
''CHAPTER III

IDENTIFICATION OF ALGAE

SEVERAL of the larger groups of algae are recognized by
their common names, such as the diatoms, desmids, armored
flagellates, euglenoids, greens, blue-greens, yellow-greens,
browns, golden-browns, and reds. Included in these groups
are numerous individual kinds which total probably more
than twenty thousand. A few of the less specific kinds of
algae have common names as well as scientific names, as for
example, the names “water net” for Hydrodictyon (fig. 2),
“green felt” for Vaucheria, “sea lettuce” for Ulva, “water
silk” for Spirogyra, and “stone wort” for Chara. Each one
of these is known as a genus (plural, “genera”) and is com-
posed of specific kinds known as species (plural also is “spe-
cies”). For example, two species of the genus Spirogyra
would be Spirogyra ellipsospora (fig. 8) and Spirogyra va-
rians (fig. 4). For the great majority of algae there are
only scientific names available, no common names having
as yet been applied to them.

Experience in water and sewage treatment plants has
demonstrated that there is considerable difficulty in recog-
nizing the various algae that are encountered and in deter-
mining which of the many present are really important. In
this manual the algae are considered and displayed accord-
ing to their significance to sanitary scientists and technicians,
rather than with regard to their evolutionary relationship
as botanists would normally classify them. Obviously only
a fraction of the total number of algae can be included, but
many of those omitted are comparatively rare types or rela-
tively unimportant in water supplies.

For convenience, most of the algae of importance in water
supplies may be characterized in four general groups, the
blue-green algae, the green algae, the diatoms, and the pig-
mented flagellates. This is a simplification of the grouping
which is used in more extensive treatises on the classification
of algae. As might be expected, there are a few miscella-
neous forms which do not fit into these four groups. The
blue-green algae include such forms as Oscéllatoria (pls. 2
and 3), Anacystis (Microcystis) (pls. 1 and 2), and Desmo-
nema (fig. 5). As the name implies, many of the specimens
have a blue-green color. They are surrounded by a slimy
coating. Their form and internal structure is comparatively
simple. The green algae are exemplified by Chlorella (pls.
2 and 3), Pediastrum (fig. 6), and Spirogyra (pls. 2 and 3).
Their most common color is grass green to yellow-green and
is localized in plastids. Reserve food is generally starch.
The desmids (fig. 7) are a subgroup of the green algae. The
diatoms are represented by the genera Cyclotella (pls. 2 and
4) and Navicula (pls. 2 and 4). They have a rigid wall con-
_ taining silica which is sculptured with regularly arranged
markings. Their plastids are brown to greenish in color.

8

In the pigmented flagellates are placed all of the swimming
algae which have flagella. H'uglena (pls. 3 and 5) and Sy-
nura (pl. 1) are representatives of this group. A compari-
son of the more significant characteristics of the four groups
of algae is summarized in table 1.

A total of 262 species of the most important algae are in-
cluded in the next six chapters of this manual, being con-
sidered according to their significance under the general
titles of Taste and Odor Algae, Filter Clogging Algae, Pol-
luted Water Algae, Clean Water Algae, Surface Water Algae
(plankton and surface-mat algae), and Algae Attached to
Reservoir Walls. In table 2, these algae are listed alpha-
betically, together with their group, the title under which
they are discussed, and the plate or figure where they are
illustrated. A “key” for their identification is included in
the appendix. A large number of additional algae are re-
ferred to briefly in chapters X and XI but are not included
in the key. More extensive manuals on both marine and
fresh-water algae would be required for their identification
(1, 2, 3,4, 6,7, 8, 10, 11, 12).

Authorities have recently changed the names of several of
the better known algae. The list of these changes which in-
volve any algae referred to in the manual is given in table 3.
Most of the changes involve genera and species of blue-green
algae and were reported by Drouet and Daily in 1956 (3).

Table 1.—Comparison of the Four Major Groups of Algae
in Water Supplies.

 

 

 

 

 

 

 

 

 

 

Algal groups
incense Blue-green Green algae Diatoms Pigmented
algae flagellates
Colones Blue-green Green to Brown to Green or
to brown yellow- light- brown
green green
Location of Through- In plastids | In plastids | In plastids
pigment out cell
barely Lk Absent Present Absent Present or
absent
Slimy coat- Present Absent in Absent in Absent in
ing most most most
Cell wall____| Inseparable | Semirigid, Very rigid, | Thin, thick
from smooth with or absent
slimy or with regular
coating spines marking
Nucleus_-___- Absent Present Present Present
Flagellum___| Absent Absent Absent Present
Eye spot____| Absent Absent Absent Present

 

 

 

 

 
''Identification of Algae 9

 

Figure 8.—Anacystis cyanea (formerly
Microcystis aeruginosa).

Figure 2.— Water
net, Hydrodictyon
reticulatum.

Figure 9.—Agmenellum quadriduplicatum
(formerly Merismopedia glauca).

 

      
   
 

Figure 10.—Phytoconis botryoides
(formerly Protococcus viridis).

 

Figure 11.—Haematococcus
lacustris (formerly Sphaerella
lacustris).

Figure 4.—Spirogyra varians.

 

 

 

 

 

 

 

 

Figure 5.—A blue-green alga, Desmonema wrangelii.

 

Figure 12.—Colonies of indefinite form in Oocystis novae-semliae.

Figure 13.—A simple filament, Anabaena
constricta.

Figure 6.—A
green alga, Pe-
diastrum bory-
anum.

   

Figure 14.—Threads are
grouped into erect cones in
Symploca muralis.

Figure 7.—A desmid, Cylindrocystis brebissonii.

496792 O-59—2
''10 ALGAE IN WATER SUPPLIES

 

For example, Jicrocystis (fig. 8) is changed to Anacystis,
Coelosphaerium is included under Gomphosphaeria, and
Merismopedia (fig. 9) becomes Agmenellum. The name of
the green alga Protococcus (fig. 10) is changed to Phytoconis
(9). The pigmented flagellate Sphaerella (fig. 11) is now
recognized as Haematococcus (1).

Six plates of illustrations in color together with photo-
graphs, line drawings, the key, and descriptions are included
for use as aids in the identification of the significant forms.
The six color-plates of important algae are the work of
artist-biologist Harold J. Walter, and were done under the
supervision of the author (13, 14). The original paintings
are on display at the Robert A. Taft Sanitary Engineering
Center, in Cincinnati, Ohio. The line drawings which are
included as figures throughout the manual were made by the
writer and published previously in two taxonomic papers
Gb).

The six plates of algae in color represent three general
areas of concern for plant operators, namely, water treat-
ment, sewage treatment, and water reservoirs. Taste, odor,
and filter clogging are the most troublesome problems faced
by many operators in water treatment plants. Representa-
tive algae associated with these conditions are illustrated on
plates 1 and 2. In connection with water pollution, natural
stream purification, and sewage treatment, the significant
algae are those whose growth or survival is closely related to
the amount and composition of sewage and other organic
wastes in the water. Plates 3 and 4 illustrate the contrasting
groups of polluted water and clean water algae. Finally, in
the reservoirs and settling basins of water supply systems are
encountered the drifting, swimming, and attached growths
of algae which can become troublesome in the raw water and
can cause nuisance conditions in the treatment plant. Plates
5 and 6 illustrate respectively the planktonic and mat-form-
ing algae of surface waters and the algae attached to the
sides of reservoirs and settling basins.

The algae as illustrated on the plates are not shown in
actual or relative size. Some of the forms illustrated are so
minute as to be visible only under very high magnification
of a compound microscope. Other forms are large enough
to be seen under lower magnification or even with the un-
aided eye. Chlorella on plates 2 and 3, and Chrysococcus
on plate 4 are good examples of minute, microscopic algae
while Lemanea on plate 4, and Chara on plate 6 are large
forms often growing to a length of several inches. Thus,
rather than having the drawing scale the same for all of the
algae, each is enlarged sufficiently to make clear its own par-
ticular characteristics. The magnification for each drawing
is given with the species name in the list accompanying each
plate.

The six color plates contain illustrations of 129 of the algae
referred to in this manual. Drawings and _photomicro-
graphs of some other forms are also included in the manual
as noted earlier. The paintings and the drawings were
prepared in such a way as to emphasize the characteristics
most helpful in the identification of unstained material in
water samples.

While illustrations may be a real aid in recognizing the

various kinds of algae, an identification “key” is essential
for distinguishing the many genera and species encountered.
An original key, limited to the 262 algae selected as most
important in water supplies, has therefore been prepared for
this manual. Since many other algae may be associated with
these forms in the water, the supplementary use of additional
treatises on algae would help to assure greater accuracy in
identifying the specimens.

When acquainted with the nature of an identification
“key”, an observer can make direct use of the device in de-
termining the name of a particular form whose essential
characteristics have been determined through study under
a microscope. It is necessary, therefore, to know what are
these “essential characteristics” that must be observed in any
specimen before the key is used for its identification. The
essential characteristics are considered under the following
headings: 1, gross structure of the alga, including shape, size,
and cell grouping; 2, cell structure; 3, specialized parts of
cells; 4, specialized parts of multicellular algae; and 5,
measurements.

GROSS STRUCTURE

The cells of algae may be isolated units so that each “uni-
cell” behaves as an independent organism. Hundreds of
genera of algae are unicellular. Examples illustrated in-
clude Tetraedron, Euglena, and Gomphonema on plate 3.
In many other algae the cells are grouped together into vari-
ous shapes of colonies such as are illustrated by Asterionella,
Hydrodictyon, Anacystis (Microcystis), Dinobryon, Volvow,
Pandorina, and Synura on plate 1 and Oocystis in figure 12.
The colony of cells may have a definite, distinct shape, as in
Volvo, or it may be indefinite and irregular, as in Anacys-
tis. Colonies in the form of threads (filaments) where the
cells are arranged in a simple linear series or chain are dis-
tinctive and very common (fig. 13). The threads may be
isolated, or obviously grouped together as in Symploca (fig.
14); they may be unbranched (simple) or branched. The
branches may be attached to the primary thread singly (al-
ternate), in pairs (opposite), or more than two together
(whorled). Anabaena, Spirogyra, Oscillatoria, and Arthro-
spira, on plate 3 are simple filaments. M¢crothammnion (fig.
15) and Audowinella (pl. 6) have alternate branching;
Stigeoclonium (pl. 6) has, in part, opposite branching; and
Chara (pl. 6) has whorled branching. Chaetophora and
Phormidium on plate 6 have filaments grouped together into
larger growths.

In a few cases the alga may be in the form of a continu-
ous, sometimes branching “tube” with no cell walls to divide
the material into distinct units or cells. The tube is de-
scribed as being “nonseptate” (having no transverse walls).
Botrydium (fig. 16) and Vaucheria on plate 6 have this type
of structure. In others, such as Hydrurus (fig. 17) and Tet-
raspora on plate 6 the whole gelatinous mass, in which nu-
merous cells are embeded, is tubular in form.

A few fresh-water algae have cells forming dense massive
“strands,” the strand being from a few to many cells thick
and with central and marginal (peripheral) cells different
''Identification of Algae ll

 

 

Figure 15.—Filament with alternate branching in
Microthamnion strictissimum.

Figure 16.—A branching, tubular,
nonseptate alga, Botrydium granu-
latum.

 

   

states

Figure 17.—Cells embedded in a gelatinous tube in
Hydrurus foetidus.

 

 

 

 

 

 

 

Figure 18.—Mature and young portions of Compsopogon coeruleus.

from one another. Lemanea on plate 4 and Compsopogon on
plate 6 and in figure 18 are examples of specialized strands.
Finally, a limited number of algae have cells arranged to
form. a flat or bent “membrane,” as indicated by Hilden-
brandia on plate 4.

In summary, the gross structural forms encountered
among the algae include the unicell, colony, filament, tube,
strand, and membrane.

CELL STRUCTURE

The three main parts of many algal cells are the proto-
plast, the cell wall, and the outer matrix. Within the proto-
plast may be the one or more separate bodies colored green, ,
yellow-green, brown, or some other color, and known as
“plastids” or “chromatophores.” In the blue-green algae
(Myxophyceae) the pigments are not localized in plastids
but are distributed throughout the whole protoplast. Some
of the protoplasts may contain bodies, other than plastids,
such as nuclei, crystals, starch grains, oil droplets, cell sap
“vacuoles,” and spherical “pyrenoids” around which minute
grains of starch collect. Pyrenoids are generally inside of
the plastids, as shown in Chlorella on plate 2 and Oocystis
and Scenedesmus on plate 5. The nucleus of the cell is pres-
ent in all but the blue-green algae, but is seldom referred to
in this manual because it is colorless and difficult to observe
without staining or other special treatment of the material.

The cell wall of algal cells is commonly a thin, rigid mem-
brane which is in contact with the outer edge of the proto-
plast and completely surrounds it. Some of the swimming
algae, such as Huglena on plate 5, do not have a rigid wall
and their protoplasts are therefore somewhat flexible, mak-
ing them changeable in form. In the green algae the cell
wall is semirigid and composed of cellulose. In diatoms the
wall is very rigid and composed principally of silica that is
sculptured with a regular, even pattern of lines and dots as
illustrated by Diatoma and Navicula on plate 2.

The outer matrix, when present, tends in most cases to be
a flexible, colorless, gelatinous material which has been
secreted through the cell wall. It often changes with age to
become pigmented, to show stratification, and to develop a
semirigid surface membrane. In most cases it assumes a
form and structure characteristic for the particular alga of
which it is a part. In Botryococcus (pl. 5), its brown color
partially hides the green plastids within the protoplasts. In
Gonium (pl. 5) it holds the cells in a flat plate, while in
Sphaerocystis (pl. 5) it forms a sphere. Dinobryon and
Trachelomonas on plate 2 have a specialized outer matrix
called a “lorica” which is rigid and of definite form. Lyng-
bya and Tolypothri# on plate 6 and Microcoleus (fig. 19)
have an outer matrix in the form of a semirigid tube-like
“sheath.”

SPECIALIZED PARTS OF CELLS

Certain additional cell parts may be characteristics useful
in identification. Some cells have a gelatinous “stalk,” one
end of which is attached .to the cell and the other to some
other object. Gomphonema and Achnanthes on plate 6 are
''12

ALGAE IN WATER SUPPLIES

 

Table 2.—Algae in Water Supplies

A List of the More Important Species

Key to Columns:
1. Alga name.

2. Group: D, diatom; G, green; BG, blue-green; R, red; FI, flagel-
late; De, desmid; YG, yellow-green.
ae Significance: A, attached ; S, surface; F, filter; C, clean; P, pol-

luted ; T, taste and odor.

4. Plate number or figure number (bold face), if illustrated.

 

 

1 2 3 4
Achnanthes: microcephala_---_-_-_-_---- D A 6
Actinastrum:
RUM OMURAUMN set oe te G 8 5
NORM RG MI Ss eee G Ss
Agmenellum:
quadriduplicatum:
PISUGA UNDG! eet Ue ees BG C 4
PeMlUddsimMa type 228. 2s BG P 3
Ampnloray  OVAHs 0225.20 D Cc
Anabaena:
Ciberadtice se he Pe Sa BG r 3
GOMsURIGhiecee sae Se Seay BG P 12
OSEAQ ING shee Oar eh a BG F 2
IeCOn CAs oi oe kT ea ee BG aL 1
Anacystis:
CyNOO eee RE ee ee BG rE :
CUI A Dace tay OA ues Maa Rs BG F 2
RIVER UA Ae si fk ee ra BG R 3
OMIA eer ee A es BG S
Ankistrodesmus:
PolGaiscep ec ee ei at es G s 34
WAT, ACIOUIATIGc © oo oo G C 4
Aphanizomenon: flos-aquae__-_-_-___-_- BG ak 1
Arshrospira: jenneri= 20. Soh BG PP s
Asterionella:
MTORR ge Gh ey he D F 2
emcees oe ee ese D YT a
Audouineila: violacea... 2-222 2253 R A -
Batrachospermum:
PAROUMRO On 5.2 Soviet Frees he R A 6
eI Aig Oe i R C
Borryococcus: ~ brauniil. ° 20022. ee G 8 5
Bulbochaete:
Deis eas tas co SR a G A 6
ia a7 F.0d en G Cc
Calothrix:
Pome ses a ee a BG A
amie tian res ic ee Nea BG C a
Cartetias -multiilis si oC a Fl Pp 3
Ceratrum: nirundinellas 22. 26s: Fl aL 1
Chaetopeltis: megalocystis__________- G C
Chaetophora:
PBUnenNaA eck a er Si es ee G A
Cle matioe mc tha ups ee G A 6
Chara:
being ot SS eg G A 6
UI DHpIS oe ee ks eee G 7
Chlamydomonas:
Urine eis ek a eS Fl oT
oneness ee Fl iP 3
Chlorella:
elliipsaiaed 2202 oe G 8
pyrenoidosa___._.- Ea G FP 2
Valoars. DUS Pegs cantare ee G PB 3
Chlorococcum: humicola_______- G iE 3
Chlorogonium: euchlorum- -_- Fl iP a
fnromulina:-rosanom. 202.0 Fl Cc 4°
Chroomonas:
Mar epeubs cs tye it et eee ee Fl C
BELONG AIns 772 Poo ye ss Fl C
Chrysococcus: \
TAT ieee CRM ts Se ee Ae Fl C
Ovalis. 22% we doy Ls Sena oy a Fl C
Mites Gels ser Sot ss etn eyes Fl Cc 4

 

 

 

 

 

Chrysosphaerella: longispina_______
Cladophora:
aegagropila___
CMS Wataes cok Se en ree ene
TPAC Se ee ati Gera 2 a oe
mlomenaias oN eee
TTRBLOUUIR Sere es 28 see eet ee
Closterium:
AGICUIARG $52 eF oe eto ee Ve a
MOUTON: ote Sy
Coecochloris: stagnina__-.----_.--.--
Cocconeis:
POCICUUS eae a ey ci ie Be
MlAceniwla ss MORE a lee es ee
Coelastrum: microporum.-.-- 2-2 -.--

Compsopogon: coeruleus___--.-.-.--

Cosmarium:
botrytises. vee ses gee
Perbianui set se Remy ee
Crucigenia: quadrata____-_._-_. oe
Cryptorlends. pigtar 17 Scien See
Cryptomonas: erosa.- -_- oe ee
Cyclotella:
bodaniga=2 2. = - ee pare
COMpta ss il oe eee
glomerata___-. _- ‘ ene
meneghiniana____. _ gee
Cylindrospermum:
muscicola_-_.- . - Gea eee
SUE er ee SA ee ete
Cymatopleura: solea_._._._-
Cybella:
GenHUle ea hc ses See Se eh
PIORtMA A a oe Se ee
Vventricosas Sete soe a

Desmidium<iereyill oo. ee ee
Diatomacvuleaness. ee 8 oo
Dichotomosiphon: tuberosus..._._._.
Dictyosphaerium:
elrenberpianuim: 6 oo
pulchellum___--_.- se einai
Dimorphococcus: ‘Gnntass
Dinobryon:
divergens_ 222 i.... pe noes Wt
sertilaria ne es ue
ROCIO Ne eee ae a
StipHatiten oe vee ee ee
Draparnaldia:
glomerata___ ses i
DUM ORAL ens Pee ae

Entophysalis: lemaniae___--..-------
Bpithemias: tunpida.. 1 to a Se es
Huastrium: oblongum: ooo. 22 soar
MuUdorings Clogans sos. oS eS
Euglena:
TD Ge SONY a AN as doe
GOSER Se yt oe he
éhrenbergits os 15 es ee oe es
CUAGIIRES Soy Sa oe ae
OR WURISe ies lot Re Se ee
Pol ynorphate =< 25 ee eS
SAnMUINe aN ees re
PLE ae) a ee ee

Vapi 2 ee is te ee ee

Fragilaria:
CAIUICUND ares Sens 2 ee Sa
CONSUIPUEHS ere cs ch oat Ss
GhOvONeDSIn= = es hae he es

Glenodinitim: palustre_____--__-_---
Gloeococcus: schroeteri_____---------
Gloeocystis:

DUG sses Or ysis re ee ee

DIAMEUOMICA oo oe ee ee
Gloeotrichia:

echimulatacns oases ane sk ae

Gomphonema:
PEIN AU Mes oe ee
OlivaceGin Sooo ea uk
DALVUlUME aS oe A ee

 

wavy BES agneo F

Qo Oa ood

eches)
QQ

goo

 

py wy

ee
Q

rROF OFM

RDAHrPQ RAH WRAQ HAVWRHDM

=
i

FQOOF QMnAH weH F

rg ie
po ae

WY QOH

Her Ae He OF DAD

 

mo

Roop

38

Nona

37
'' 

 

 

 

Identification of Algae 13
1 2 3 4 1 2 3 4
Gomphosphaeria: : : Pediastrum:

Pate Tieng he ae |g nes pce Ugo BG S 5 DOFYANUM: (eo aos le See oe ee G 8 ,
Coumelbniype 2 20 2 ose BG S Guplex2 3) es G 8 51
kuetzingianum type_...-_..-_--- BG a 1 MetrAgE 22 Se Se bose ees G L.

WAC Minge ke om oi oe Se BG 8 Peridinium:

Goniumy; pectorale _- ---. ).- Fl 8 5 Cinetun ss ee eet Fl fe tf
Gyrosigma: attenuatum_-_-____------ DD 8 wisconsinense ____---------------- Fl F
Hantzschia: amphioxys__--...______- D P Phacotus: lenticularis.-..-.-..------ Fl Cc 4
Hildenbrandia: rivularis._-_.-------- R Cc 4 Phacus:
Hyalotheca: mucosa_--------------- De 8 oe one e enon n eee +--+ ------ " S 5
Hydrodietyon: reticulatum__........_]G RT || 3 Riis ee P 3
Kirchneriella: lunaris_.._-_----------- G s ee BG P 9
, ‘ autumnale______-----------------
oe Ree ag ore R Cc 4 inundatum:....02--.5. 2.022 ro2 BG Cc
Pe FI P Teta 622 2 eee esc BG A,S
Nosia ewes. foe Fl P 3 uncinatum____.__.____-__--------- BG A,P 6
Lyngbya: =

inne ae eee tell BG P 3 Phytoconis: botryoides_____--------- G A 9

iipephenent.. 22.2 222) ltl} BG A 6 Pi ee

Otin@edt ee lll BG A innularia:

WEtEIGG@On 20 2o 02 le LLL BG S nobilis... .-~---------------------- D C 4

; 1 subcapitata_...--.--------------- D C
Mallomonas: caudata___.-_--------- Fl C,T | 38 Pithophora: oedogonia__------------ G A 41
Melosira: Plectonema: tomasiniana.____-___--- BG 8

Cremtietaee Se Le D Ss Pyrobotrys: P

Pramas) ess AU D F 2 gracilis. ---.--------------------- Fl

PO ae D F,P stellata2 i200 02s tse ule te Fl P 3

Meridion: ‘cireulare___...-.._...__-- D C 4 Rhizoclonium: hieroglyphicum_ - ----- G C,A a
Micractinium: pusillum____...----- ~~ G Ss 5 Rhi ‘ial “3 g
Micrasterias: truncata___-- pee De C 4 izosolenia: gracilis. -.-.----------- D CG
Microcoleus: subtorulosus__._-_-__-_- BG C 4 Rhodomonas: lacustris _------------- Fl 4
Microspora: amoena______.-__--___- G A 6 Rhoicosphenia: curvata___---------- D A
Mougeotia: Rhopalodia: gibba_..--------------- D Ss

Penitery 32052 lot G s Rivularia: Fe

Reabauineee ag le G s 5 dura... -~----------------------- BG 2

Sphaerdearpa- 252. 0.22 G F haematites___-------------------- BG T

Naviculas Scenedesmus:

ehyptocephala. 2). eke D Pp abundans- - ---.------------------ G T

exigua var. capitata--....-_------ D C bijuga-.------------------------- G s

BNNGH ieee ee D C “4 dimorphus- ---.------------------ G 8

Beer Be ae ee 0 ‘ 2 quadricauda___.......------------ G P,S a

fe cc D 8 Schizomeris: leibleinii-___--.----.--- G A | mR

Natella: a Schroederia: setigera__.....--------- G 8
Nee G a Scytonema: tolypothricoides-_--__----- BG 8
ee G T 1 Selenastrum: gracile. _____...------- G 8
Nitzschia: Sphaerocystis: schroeteri____--------- G 8 5

Molenioites 2 ee D Pp Spirogyra:

HiMeAMseeee ee D C communis. ._-----~---------------- G P 3

DoleHe eee oo D EP 3 abet oo ooo 2 ooo ee = --------- Ho :

: : majuscula. 005 2 es ee
Nodularia: spumigena_-_------------ BG | 7 poriieatia Oe ee G F 2
Nostoe: Varlans...- 22-2 G 8 36
Sermon ee BG Ss Spirulina: nordstedtii__.-------.----- BG S
pruniformes 26666 BG mt Spondylomorum: quaternarium__-_---- Fl EF
Oedogonium: Staurastrum:

bestii : G A paradoxum___________-___------- De - 1

ee a) : polymorphum——— === 2-2 De s

idioaAndrasporum.:__-- 2... =.=. G S s iadipertieiep gs gee he ea Gk ke ose y 4

Rae ee G ‘A 6 Stee cae p oenicenteron_.- Sees 5 5

Oocyatisborgei. 9-2 G S 5 ; ae no IBeuE: D F

Ophiocytium: capitatum____________- G S er eee = otc rete Sg

Oscillatoria: hantzsehii.-_--------------------- iz ne 5
oe IMASOTAC oo oo eS eR ee a ee

pets pues a eee : Stichococeus: bacillaris--_..------- 3 G v

ee) Be | ge |g | Stgetoniom: :

Chlorine ee BG Fp 3 lubr Seah Reeg eee G S 6

GUinsoe prs) eS a BG 7 stagnatile_---~------------------- G P

TORMORNS ct ee BG Pp Ss fone. .-1- Gee ee a es BG A 3

fiethorie Te BG P 3 stigonema: minutum...-.2----------

Hinge ae a oe, BG P 29 Surirella:

Ginbin ere ye i A BG F OVatate obese lee eee D Le 4

piinceper i BG F,P { Pd splendida- -_---.--------- eo D Cc 38

pseudogeminata.___..._.___..____ BG F Synedra:

pode ae BG FE 3 ACM SN ee ee ek a ee D F 2

PRS Eilees <i GF BG F Var anousbissiinn: cis fe ao D C

Sistemas seg ee eae BG F 2 Warneradianen ie at eee D F

WON ee ee a BG ; 30 GRDINATAI ong ae a ee D 8

almolla mucosa. G A,F 9 pulchellas esas a D F
Pandownas.morum 9.006 bo) Fl P,T 1 Ufa na ges es ae D fh 1

 

 

 

 

 

 
''14

ALGAE IN WATER SUPPLIES

 

Table 2—Continued

 

 

1 2 3 4

DO VMMRA MVCN AL ss Oo eS Fl ec { ms
Tabellaria:

POMC BUEAUH © Ses SU ey D Bt 1

HOGG UNOR DE oko hrc Me oh Be D i 2
Metaedron: muUbiCuMme: 2 <i eS G P 3
Mewaspora: eelapinoss. oo G A 6
pow pounmm tenuis. 222 3 BG A 6
Trachelomonas: crebea___----.------ Fl F 2
Tribonema:

QTE) y CHU cio eee Fe Roe eA VG F 2

WANS SO a eRe Ss ee YG s
Ulothrix:

Godtintinemcss Soc! Vo ey G C 4

GtiGuhinine cee sa SNe sate G Ss

aI eer ee ee ha G F

OR re ers EA oe Set G A { a
Uroglenopsis: americana____-_------- Fl T 1
Vaucheria:

[ec it ig es A i eee G A,C 39

ReaerkiNeh rN eee ne ie i ahaa G A { o
VOUVIOXe AUTOS Oe eS oc Pec Fl T 1
Zygnema:

RTE ere Vee ea G F

MOCtINE Mio s. sMe a os es G 8

Bieri Gs ee Fee i ee G Ss 5

 

 

 

 

Table 3.—Recent Changes in Names of Algae

 

 

Old name New name
MpBaMOeRpsAs. Se see Anacystis.
PRM mHOUHeCG. 25 552 eee es Coccochloris.
@hamaesipnon. ero et Entophysalis.
Chamaesiphon incrustans_----_--_- Entophysalis lemaniae.
nenineneld ee eS Audouinella.
Chanastrapilise) 20S arts Chara globularis.
Whiamydoueityss 665 ue Ste Pyrobotrys.
OA OCOC RUB ice ie ee Anacystis.

Chroococcus limneticus__-=.=_----
Chroococeus turgidus... 522-7
larOCyatiIb = 2s 2 ey
@oalosphaenioim.. 3 2 Fee
Coelosphaerium kuetzingianum__-_-_
Coelosphaerium naegelianum___----
Hine@yanerma. oe eee
Encyonema paradoxum__-__--_----
Pugiona-pistitormis. 222022 ee
GGEOGa iste 22 sos ee
Gloeocapsa conglomerata- --------
MeO Enete bs. Fe es
Gilocotnecedinearis..2 = 22 ae
Gomphosphaeria naegeliana ______
bipropecditrnns: <0 a ST ores ees
Wenismopedian S20 oe
Merismopedia glauca________-_-__
Merismopedia tenuissima_________
LASS TC PINOTCA 2211 el cn mB
Microcystis aeruginosa___________
demic oe se
Oedogonium crassiusculum var.
idioandrosporum.

LE SONS Eg ne ee ee
Polycystis: aeruginosa__._____.-_-
IPROUGCOCCUBR: ta. Se ne
PrOLvococcus vitidis. 2 oe
RUE DeL A ete eek ee ey
MpITUling jen pene ES ea
PW MECUOCOCCIIC a hae
Synedra delicatissima____________

 

Anacystis thermalis.

Anacystis dimidiata.
Anacystis.

Gomphosphaeria.
Gomphosphaeria lacustris.
Gomphosphaeria wichurae.
Cymbella.

Cymbella prostrata.

Euglena agilis.

Anacystis.

Anacystis montana.
Coccochloris.

Coccochloris peniocystis.
Gomphosphaeria wichurae.
Microcrosis.

Agmenellum.

Agmenellum quadriduplicatum.
Agmenellum quadriduplicatum.
Anacystis.

Anacystis cyanea.

Diatoma.

Oedogonium idioandrosporum.

Anacystis.

Anacystis cyanea.
Phytoconis.

Phytoconis botryoides.
Haematococcus.
Arthrospira jenneri.
Coccochloris.

Synedra acus var. radians.

 

shown with stalks. In many cases the cell may become de-
tached from the stalk very readily. Gomphonema on plate
3 is illustrated without the stalk although it is originally
present in this genus.

Knobs or spines may be found extending from the cell
wall, or the cells may have sharp spine-like ends. Méerac-
tinium on plate 5 has true spines while Ankistrodesmus on
plate 4 and Scenedesmus (fig. 20) have spine-like tips.
Knob-like swellings on the cell wall are shown on the large
cell of Chlorococcum on plate 3.

Swimming (motile) cells often are supplied with one, two,
or occasionally more than two flexible, whip-like hairs known
as “flagella,” extending from the front (anterior), side (lat-
eral), or back (posterior) of the algal cell. Lateral flagella
are found in Merotrichia (fig. 21) while anterior flagella are
shown in Pleodorina (fig. 22), and in two views of Gonium
(fig. 23). A reduction in the illumination of the microscope
field may help in making the flagella (singular, “flagellum”)
visible. Swimming cells also may contain a single small red
or orange body called an “eye spot” in the protoplast. This
eye spot is generally located near the anterior end. Car-
terta and six other motile algae are illustrated on plate 3.

Several special terms are required in the description of a
diatom cell. The wall (frustule) of the diatom is composed
of two approximately equal halves, the one, like a cover
(epitheca), fitting with its edge over the edge of the other
(hypotheca). When the cell is lying in the microscope field
so that these overlapping edges are visible, the diatom is
presenting its “girdle” view. If the cell is lying so that the
top of the epitheca or bottom of the hypotheca is visible, the
diatom is presenting a “valve” view. In Gomphonema on
plate 6 the left hand cell is in girdle view and the right hand
cell is in valve view. These views are shown together in
Gomphonema on plate 3. When diatom cells are fastened
together into a filament or ribbon, it is the valve surfaces —
which are attached together, so that the diatoms in the col-
ony are always seen in their girdle view. Thus, the two
attached cells in Diatoma on plate 2 present the girdle view
while the isolated cell to the left is shown in valve view.

In diatoms the wall markings and partial partitions, par-
ticularly those visible in the valve view, are important in
identification. The many fine lines or lines of dots (punc-
tae) extending from the edge of the valve toward the center
are known as “striae,” or, when thicker, as “costae.” There
may also be a longitudinal line called a “raphe” or “true
raphe,” extending from one end of the cell to the other, but
broken in the middle. If there is merely a clear space with
no striae crossing it, rather than a longitudinal line, the
space is known as a “false raphe” or “pseudoraphe.” Mo-
tile diatoms generally have a true raphe which is apparently
associated with their ability to swim or crawl. Partial wall-
like partitions are called “septa” and extend lengthwise or
crosswise into the protoplast. They appear as coarser lines
than the striae. On plate 4, Navicula shows striae com-
posed of punctae while Pinnularia has costae. Both dia-
toms have a true raphe. In Diatoma and Synedra on plate
2, a pseudoraphe is present. The former also has transverse
''Identification of Algae iS

 

septa. Longitudinal septa are seen in the girdle view of
Tabellaria on plate 2.

There are two major groups of diatoms, those circular in
valve view, with radiating striae, and those elongate in valve
view, with striae that tend to be transverse. The former are
known as the “centric” diatoms, and the latter as the “pen-
nate” diatoms. On plate 2, Cyclotella and Melosira are
centric in form while Navicula and Cymbella are of the
pennate type.

SPECIALIZED PARTS OF MULTICELLULAR ALGAE

The shape of the end of a filament is an important diag-
nostic character. The end cells may be essentially the same
as other cells of the filament or there may be either a grad-
ual or an abrupt decrease in width (attenuation) to a point
or even to a long spine or hair. On plate 6, Cladophora and
Lyngbya have terminal cells essentially like other cells in
the filaments while Stigeoclonium shows gradual, and Bud-
bochaete, abrupt attenuation. Some of the filaments of blue-
green algae have terminal cells which are swollen (capitate)
or are covered with a thick cap-like or conical membrane
(calyptra). These are present in Oscillatoria on plate 2
and Phormidium on plate 6.

Some multicellular blue-green algae also have occasional
special cells associated with the normal ones. One type,
the “heterocyst,” generally is swollen, has a clear, colorless
protoplast, and a thick wall with a knob-like thickening on
the inside of the wall at the place or places where the cell
is connected to the adjacent cell or cells. Heterocysts are
shown in Anabaena and Aphanizomenon on plate 1. An-
other specialized cell, the resting spore (akinete), is swollen,
has a dense, granular protoplast and a thick wall. It is
illustrated in Anabaena on plate 1 and Cylindrospermum
and Vodularia on plate 5.

There are a number of other specialized cells which may
be encountered in some of the algae but these are too varied
or too infrequent to be dealt with here in detail. Many
are reproductive cells (figs. 24, 25, 26,27). In some forms
the sexual reproductive cells must be present before iden-
tification of particular species can be made. These struc-
tures are well described in other references (1, 2).

A peculiar type of branching of filaments found in cer-
tain blue-green algae may need to be explained. It is called
“false branching,” and is formed when a thread of cells
splits crosswise. One or both segments break through the
surrounding sheath at this point and a portion moves out to
the side of the original thread, thus giving the appearance
of branching. False branching is evident in 7olypothrix
on plate 6, while normal or true branching is shown in
Audouinella and Chaetophora on plate 6 and of a blue-green
alga in Vostochopsis (fig. 28).

MEASUREMENTS

There are some instances where it is necessary to know
the diameter or the length and width of the algal body
(thallus) or of the individual cells before species belonging

to the same genus can be distinguished. The unit of meas-
urement is the micron, designated by the Greek letter “yw”.
It is one one-thousandth of a millimeter or approximately
one twenty-five-thousandth of an inch. A linear scale on
a glass disc (ocular micrometer) which can be placed on the
interior shelf (diaphragm) of a microscope eye piece (ocu-
lar) can be calibrated in microns with the aid of a stage
micrometer. The ocular micrometer can then be used to
obtain measurements of algae. A Whipple micrometer,
used in plankton counting, can also be calibrated in microns
and thus serve in a similar manner.

TYPICAL DESCRIPTIONS OF ALGAE

A few examples of descriptions of algae adequate for
their identification are given below as an indication of the
information which would need to be obtained by micro-
scopic observation before attempting to determine the genus
and species name of the specimen.

Example No. 1: See Chlorella on plate 2. Unicellular or
in loose irregular colonies; cell spherical; no outer matrix;
no projections or markings on the wall; protoplast with one
cup-shaped green plastid filling most of the cell; one prom-
inent pyrenoid in side or base of plastid; no great variation
in size of cells; diameter of cells 83-5 microns.

Example No. 2: See Phormidium on plate 6. Short cy-
lindrical cells in simple filaments which are aggregated to
form a mat, with formless gelatinous matrix between them.
Ends of filaments rather abruptly attenuate, bent, capitate,
and with a conical calyptra. Protoplasts homogeneous, blue-
green throughout, no plastids; no heterocysts nor akinetes.

Example No. 3: See Fragilaria on plate 5. Numerous
cells united side by side into a ribbon. Contact of adjacent
cells is continuous from one end of cell to the other. Cells
with fine transverse striations in the wall but absent in a
wide band across the center. Pseudoraphe present; septa
absent. Valve view narrowly elliptical but with sides
parallel much of the way; ends capitate. Girdle view rec-
tangular, protoplast with two brown linear plastids, one on
each side. Cell length, 25-100 microns.

Example No. 4: See Chrysococcus on plate 4. Unicellu-
lar; protoplast with two brown lateral plastids and anterior
red eye spot. Protoplast surrounded by a brown spherical
lorica with internal swelling at posterior end and an open-
ing surrounded by a thickened ring at anterior end through
which extends one flagellum that is about twice as long as
the lorica. Cell very small, diameter of lorica 6 microns.

USE OF “KEY” FOR IDENTIFICATION OF ALGAE

In order to use the key, first observe the specimen and
determine its “essential characteristics.” Referring to the
key, lines “1a” and “1b” at the beginning of the key are then
compared with one another and with the “essential charac-
teristics” of the specimen. At the end of the line which
agrees with the specimen is a number. Turn to the place
in the key where this same number is listed on the left hand
side of the page and is divided into lines “a” and “b”.  Re-
''16 ALGAE IN WATER SUPPLIES

 

 

Figure 19.—Microcoleus paludosus, showing a single thread and a Figure 25.—Enlarged terminal reproductive cells on filaments of
group of threads surrounded by a sheath, under high and low Audouinella violacea.
magnification.

Q
Figure 20.—Scenedesmus \ Figure 26.—Terminal cells
quadricauda, showing spine- specialized for sexual repro-
like extensions on the termi- Y duction in Vaucheria arecha-
nal cells. - valetae.

Figure 21.—Lateral flagella in
Merotrichia capitata.

 

 

 

Figure 22.—Anterior fla- Figure 27.—Thick walled zygospores formed during sexual repro-
gella on cells of Pleodorina duction in Zygnema normani.
illinoisensis.

 

Figure 23.—
Posterior and
lateral views of
anterior flagel-
la on Gonium
sociale.

  

Figure 24.—Two spore-
producing cells on fila-
ments of Trentepohlia Figure 28.—True branching in the blue-green alga, Nostochopsis

aurea. lobatus.

 
''Identification of Algae 17

 

peat the above process and continue until a name for the
alga rather than an additional number is given at the end
of the line. Thus, in determining a name for “Example
No. 1,” above, the following lines from the key are selected,
until line 283b is reached giving the species name for the
alga: 1b, 123b, 173b, 184b, 185b, 225b, 230b, 232b, 276a, 277b,
279b, 280a, 281b, 282a, 283b (Chlorella pyrenoidosa).

When a name has been reached in the key, reference can
then be made to illustrations and descriptions of that par-
ticular genus or species in this and other manuals to de-
termine whether the specimen seen under the microscope is
correctly identified. Three recent manuals on algae in water
supplies have been published abroad, one in Danish (17),
one in Japanese (18), and one in German (19).

REFERENCES

1. The fresh-water algae of the United States.
McGraw-Hill, N.Y., 719 p. 1950.

2. A treatise on the British freshwater algae. New and revised ed.
G. S. West and F. BE. Fritsch. Univ. Press, Cambridge, England,
534 p. 1927.

3. Revision of the coccoid Myxophyceae. F. Drouet and W. A. Daily.
Butler Univ. Bot. Stud. 12: 1-218. 1956.

4. The Characeae of Indiana. Fay K. Daily. Butler Univ. Bot. Stud.
11:5-49. 1953.

. Nomenclatural changes in two genera of diatoms. Ruth Patrick.
Notulae Naturae, Acad. Natural Sci. Philadelphia, No. 28, 11 p.
1939.

6. Synopsis of North American Diatomaceae. Part II, Naviculatae,

Surirellatae. C. S. Boyer. Proc. Acad. Natural Sci. Philadel-
phia 79: 229-588. 1927.

Ed. 2. G. M. Smith.

1

10.

at:

12.

13.

14.

16.

17.

18.

19.

. The genus Euglena.

. The algae of Illinois.

. Algae of Marion County, Indiana.

Mary Gojdics. Univ. Wis. Press, Madison,
Wis., 268 p. 1953.
L. H. Tiffany and M. EB. Britton. Univ.

Chicago Press, Chicago, Ill., 407 p. 1952.

. A preliminary study of the algae of northwestern Minnesota. F.

Drouet. Proc. Minnesota Acad. Sci. 22: 116-138. 1956.

Algae of the western Great Lakes area. G. W. Prescott. Cran-
brook Inst. Sci., Bloomfield Hills, Mich., Bull. 31, 946 p. 1951.

Bacillariophyta (Diatomeae). F. Hustedt. Heft 10 in A. Pascher,
Die Siisswasser-Flora Mitteleuropas. Gustav Fisher, Jena,
Germany, 466 p. 1980.

The marine and fresh-water plankton. C. C. Davis.
Univ. Press, East Lansing, Mich., 562 p. 1955.

Algae of importance in water supplies. Plans for a manual with
keys and color plates. C. M. Palmer and H. J. Walter. News
Bull., Phycological Soc. Amer. 7 (No. 21) : 6-7. 1954.

Algae of importance in water supplies. C. M. Palmer and ©. M.
Tarzwell. Public Wks. Mag. 86 (No. 6) : 107-120. With 6 color
plates. 1955.

Mich. State

A description of thirty-two
forms. C. M. Palmer. Butler Univ. Bot. Stud. 2:1-21. 1981.

Additional records for algae, including some of the less common
forms. C.M. Palmer. Butler Univ. Bot. Stud. 5: 224-234. 1942.

Dansk Planteplankton. G. Nygaard. Gyldendalske Boghandel
Nordisk Forlag, Copenhagen, Denmark, 52 p. With 4 color
plates. 1945.

The easy classification of important microorganisms in Japanese
water supplies. S. Kawakita. Jour. Japanese Waterwks. and
Sewerage Assn., Nos. 251, 258, 257, 258, 263, 265. 1955-56. (In
Japanese. )

Das Phytoplankton des Siisswassers. G. Huber-Pestalozzi. Band
16, Teil 1-4. In Die Binnengewidsser by A. Thienemann. BH.
Schweizerbart’sche Verlagsbuchhandlung, Stuttgart, Germany.
1938-55.
''CHAPTER IV

TASTE AND ODOR ALGAE

ONE of the requirements in the production of potable water
for modern communities is that the product shall be free of
obnoxious and abnormal tastes and odors. Of the several
causes of these tastes and odors, the algae present in the raw
water supply are recognized as being either the primary, or
at least one of the most important. A comprehensive study
has been made of algae of the central Missouri River (1).
In addition, the time of occurrence of tastes and odors was
recorded at the treatment plants of cities and towns in that
area, using the Missouri River as their source of water. It
was found that practically all of the taste and odor occur-
rences were associated with the presence of algal blooms and
that the few exceptional cases came during declines of dense
algal growths. It is evident that, for the central Missouri
River area as well as for many other parts of the country,
algae are involved, either directly or indirectly, in the estab-
lishment of conditions leading to taste and odor production
in water supplies.

A nationwide survey reported in 1957 (2) indicated that
algae were considered by water works officials to be the most
frequent causes of tastes and odors in water supplies, with
decaying vegetation second in importance. The decay or
decomposition is brought about by fungi and bacteria, in-
cluding the actinomycetes. Often a considerable proportion
of the decaying vegetation is composed of dead algal cells.
The odors that are produced through the activities of fungi
and bacteria may be either from the intermediate products
formed during the decomposition or from special substances
that are synthesized within the cells of the microorganisms.
The latter appears to be true in the case of actinomycetes.

A few algae are well known for the production of specific
distinctive tastes and odors while a larger number of others
are associated with tastes and odors that vary in type accord-
ing to local conditions. Certain diatoms, blue-green algae,
and pigmented flagellates are the principal offenders but
green algae, including desmids, may also be involved.
Thirty-nine species have been selected as representative of
the more important taste and odor algae. They are listed
alphabetically under their respective groups in table 4, and
eighteen of these are illustrated in color on plate 1. Other
genera and species, in addition to the ones selected, must be
considered also as potential offenders and many of these are
included in table 5. Most of the reports dealing with spe-
cific instances where algae are regarded as the cause of taste
and odor, do not give the species names of the particular
forms involved. In the following discussion of this prob-
lem, therefore, reference is made to the genera rather than
the species of algae.

18

TYPICAL ODORS FROM ALGAE

Some of the algae produce an “aromatic” odor which is
described more specifically for certain organisms as that re-
sembling a particular flower or vegetable. Common ex-
amples of these would be geranium, nasturtium, violet, musk-
melon, and cucumber. In some cases it is described as an
attractive spicy odor, but in others it may be very objection-
able, as for example, a skunk or garlic odor. Some pig-
mented flagellates and diatoms produce the aromatic odors
when these organisms are present in small numbers in the
water.

A second type of odor, the “fishy” odor, is produced often
by the same algae that are responsible for the aromatic
odors. The organisms generally are present in much larger
numbers when the fishy odor is evident. More specific terms
that have been used to describe the fishy odors of various
algae are clam-shell, cod-liver oil, sea weed, Irish moss, rock-
weed, and salt marsh. The differences between these are
probably insignificant in water supply studies.

A third type of odor is the somewhat aromatic one which
is described as “grassy.” It is the most common one pro-
duced by green algae and generally is apparent only when
the organisms are present in large numbers. It is reported
also for certain blue-green algae and occasionally for diatoms
and pigmented flagellates.

The fourth type of odor is the one which includes those
described as “musty” and “earthy.” The latter is commonly
associated with actinomycetes (3, 4) and with a few algae.
It can vary from mild to decidedly pungent. The earthy odor
of soil also has been considered to be due to the presence of
actinomycetes. The very common musty odor in water is
encountered in the presence of certain blue-green algae and —
a few other forms. It has been described by additional
terms such as potato bin and moldy. Some waters have been
reported as having weedy, swampy, marshy, peaty, straw-
like and woody odors and these are possibly a modification
or a combination of the grassy and musty odors.

A “septic” odor has been associated frequently with the
presence of large accumulations of blue-green algae and
occasionally of the green algae, Hydrodictyon and Clado-
phora. Other names applied to this type of odor are pig-
pen, foul, objectionable, vile, fermentation, and putrefactive
(5). As these terms suggest, it is produced as a result, of
the decomposition of masses of algae, especially where a lack
of sufficient oxygen permits the formation of odoriferous
intermediate products from the algal proteins.

Chlorophenolic, iodoform, or medicinal odors may be pro-
duced by the action of chlorine on the products of certain
''Taste and Odor Algae : 19.

 

algae although somewhat similar odors may be present in the
water at other times because of industrial wastes.

MEASUREMENT OF ODORS

For the measurement of odors in water the threshold odor
test is commonly employed (6). The threshold odors due to
algae tend, in some areas, to be comparatively low, ranging
from 1 to 14, but in other areas they frequently go up to 30
or 40, and occasionally reach as high as 90 or more. Algal
odors are generally objectionable, however, even when the
threshold odor number is low. For satisfactory treatment,
the threshold odor usually has to be reduced to 5 or Iess.
However, each water supply and often each odor outbreak
must be judged independently, in determining the threshold
number below which the water is considered palatable.

In some plants the treatment is instituted as soon as any
taste and odor algae increase to a predetermined number of
areal standard units per ml. The number varies according
to the particular kind of alga involved; for Asterionella it
may be 3,000, and for Synura, 200 (7).

Tastes produced by algae are seldom separated from and
are often confused with odor. Sweet and bitter are the two
tastes which have been recorded and it is quite possible that
a sour taste may be present whenever the odor is acid or is
the putrefactive, septic, or pigpen type. A salty taste ap-
parently has not been recorded as an accompaniment of the
fishy, clam-shell, salt marsh, rockweed, Irish moss, or sea
weed-like odors.

An additional sensation which the tongue can detect might
be listed as the “feel” or “touch.” Included here would be
the slick or “oily” feel as well as a “metallic,” a “dry,” and
and an “astringent” sensation. Odor, taste, and feel, as re-
corded for each algal genus are given in table 5. The word
“flavor” could be used as an inclusive term embracing taste,
odor, and touch or feel (8).

~PRINCIPAL ODOR-PRODUCING ALGAE

Synura is one of the more potent algae in production of an
odor in water which is often described as resembling that of
a ripe cucumber or muskmelon. A comparatively few col-
onies per ml. may be sufficient to catise a very perceptible
odor. This organism also produces a bitter taste in the water
and leaves a persistent dry metallic sensation on the tongue.
When present in large numbers, this, as well as other flagel-
lates, may develop a fishy odor. -In Massachusetts, for
example, Dinobryon, Uroglenopsis, and the “armored” flagel-
late Peridinium produced a strong fishy odor in a large reser-
voir holding over 600 million gallons of water. These forms
~ developed in February under a 16-inch layer of ice (9).
There is some evidence that Uroglenopsis is stimulated to
rapid growth following an abundant growth of other algae.

In California one of the worst offenders is the armored

- flagellate Ceratiwm which produces a fishy to pronounced

septic odor. The organism is capable of very rapid multi-
plication and may develop in large numbers during any sea-
son (10).

Table 4.—Taste and Odor Algae, Representative Species

Group and Algae Plate

Blue-Green Algae (Myxophyceae):
Anabaena circinalis
Anabaena planctonica
Anacystis cyanea
Aphanizomenon flos-aquae
Cylindrospermum musicola
Gomphosphaeria lacustris, kuetzingianum type 1
Oscillatoria curviceps
Rivularia haematites

Se

Green Algae (nonmotile Chlorophyceae, etc.):
Chara vulgaris -
Cladophora insignis
Cosmarium portianum
Dictyosphaerium ehrenbergianum
Gloeocystis planctonica
Hydrodictyon reticulatum 1
Nitella gracilis 1
Pediastrum tetras
Scenedesmus abundans
Spirogyra majuscula

Staurastrum paradoxum 1
Diatoms (Bacillariophyceae):

Asterionella gracillima 1

Cyclotella compta

Diatoma vulgare 2

Fragilaria construens

Stephanodiscus niagarae

Synedra ulna 1
Tabellaria fenestrata 1

Flagellates (Chrysophyceae, Euglenophyceae, etc.):
Ceratium hirundinella 1
Chlamydomonas globosa
Chrysosphaerella longispina
Cryptomonas erosa
Dinobryon divergens 1
Euglena sanguinea
Glenodinium palustre
Mallomonas caudata
Pandorina morum
Peridinium cinctum
Synura uvella
Uroglenopsis americana
Volvox aureus

aoe ees

Dinobryon develops in the southern end of Lake Michi-
gan, in June and July, almost every year, in numbers suffi-
cient to impart a prominent fishy odor to the water. As
many as 700 areal standard units per ml. of this alga have
been reported and it has represented, at times, up to 47 per-
cent of the total algal count. Its odor has the reputation
of being readily adsorbed by activated carbon. In spite of
this, it is estimated that one treatment plant required over
$70,000 worth of the carbon to control, for a period of 2
months, the odor due specifically to this alga (11).

Asterionella is considered one of the worst offenders among
the diatoms, having a characteristic aromatic geranium-like
odor that changes to fishy when the alga is present in large
numbers. TZ abellaria produces a similar effect, while Syne-
dra has an earthy to musty odor and Stephanodiscus is
blamed for a “vegetable to oily taste” with very little odor.

Certain blue-green algae are well known for developing
very foul “pigpen” odors in water. Three of these algae,
illustrated on plate 1, are Anabaena, Anacystis (formerly
known as Microcystis, Polycystis, and Clathrocystis), and
Aphanizomenon. All of these are capable of collecting in
large masses sufficient to form water “blooms.” The foul
odor undoubtedly develops from products of decomposition
as the algae begin to die off in large numbers. These same
''20

ALGAE IN WATER SUPPLIES

 

blue-green algae, together with others such as Gomphosphae-
ria (which now includes Coelosphaerium), Cylindrosper-
mum, and Rivularia have a natural odor which is commonly
described as “grassy.” This often changes to the odor of
nasturtium stems, probably as a result of oxidation.

Green algae are less often associated with tastes and odors
in water. In fact, their growth may help to keep in check
the blue-green algae and the diatoms and thus be a positive
factor in the control of water quality.
dictyon (water net), the desmid, Staurastrum, and the large

However, Hydro-

odors.

Table 5.—Odors, Tastes, and Tongue Sensations Associated With Algae in Water

massive stone-warts, Vitella and Chara, may offend rather
than help in this biological competition between types.
Dictyosphaerium is regarded as one of the worst offenders
among the green algae, giving a fishy, as well as a grassy to
nasturtium odor (12). Some of the swimming green algae
which are listed with the flagellates, including Volvoa,
Pandorina, and Chlamydomonas, are able to produce fishy

Research is now being conducted at the Robert A. Taft
Sanitary Engineering Center to determine what particular

 

Odor when algae are—

 

 

Algal genus Algal group Taste Tongue
sensation
Moderate Abundant
Netinastrumy 22 oss Se Greenies san eee oe ee Grassy smusty. 222550. be oe ee
IAM ROMS eet eee te re ee Blue-green’ @ 00 Grassy, nasturtium, BCpuee ek. Ces Waa as ee
musty.
AMADACNOPSIS.. 2022-2522 555 Blveeyreenuee es ev A i a ae GTASBY. <2 2. SG es i ne
IAMAG VAIS eros Pe ee Blue-sreenuss) os Grassy. oe POP UECe 6 ok sera cia Sweet... ws
Aphanizomenon = 2.2 222222 Biwerereene sci S eS Grassy, nasturtium, Depoice Sater. cea Sweet.22 -2as422 Dry.
musty.
msterionelian 2) .2 2 - 282 Digtont. se eens a Geranium, spicy 22.-2224- Wishy. 2 228 a a
Conti os ee Hlagellates: sol 2 2b Wishiy. soos 2 Sy oe Septien 6 tc suc Sos 6 ee Bitter 23
harnesses ac. oe ee ae Greens ls ee tase eae Skunk; earlic. oo. 22 si Spovled.earlicc cs 20. eee
Chlamydomonas..2. <2 .2>_ Wiageligtes coe es oe Musty, erassy. 22) 8 Wishy,;6epuie. 20 2. a Sweet 25. 28 Slick.
OMOrellas eee ee Sos Greene see Hoc CP ON eee oe a eee AVIS ye ee eer
Chrysosphaerella_____------- PRION pe ar ss EA Se at Fe Je RTS EVs i el es oe i
Wladophora= 2. 8. ou es Greene set ee Can eae eee ee ee Sepiie i SUS Whe on sec ee oe ae
(Clathrocystis) 3. = 222s See Anacystis.
Glostenuin es ya es MOOT oie es Se ae at Oy Ut ae Cr si a Oe aed
(Coelosphaerium)______------ See Gomphosphaeria
Cosmariume:*: =. PEO VO Ce eet oe gO le Dare Stag Grassye. ee Sc eee
Grymtomonass (222 32522 3st Blagellates 2 eet lS Wiclets So. a os Wiolete 2 Saas Sweet gk ks
Wycloulllai. = os ove te od IDTstonir ss eee ee ee Geraniume os 2 rela Wishy (See cere iu) ase | ee ey eee
Gylindrospermum 2. 2. Blue-greene. | ed > Grassy 28.2 oe eevee Septigenet iol Ee es eee
MBI LOMA soar ee ee DRA O MA: Ohi eee ads Aare ee, eae OL ae ee eee ATOMAVICE ce oe lie Sees ae es ae ee
Dictyosphacrium=< ==. = 2 Greent ee ee hse vay Grassy, nasturtium __-_--- Wishivet 2c sos ed Ba eee :
Dinoprygn epee kts Plagollate sess ye Violets ea Wish ye. nas Te ee Slick.
PIC OT ae er ees oP ae ee Mia@ellate Shes Sas ee eee ele Rishy. = 2c os las
Mnplon gees A os os se AUlawellate scold et ee a ass A) ee Hishiy co ee aoe Oo oe Sweet. “ie
rain en alt Rs es PATON gts ee Ee Geéraniutie S252 42 sue Misty. 6 ioe oe ee ;
Glienoediniums ) 2. ve on oe Wiapellatevenere Se eS eo ee ee Wishy 2205 See oe Ne Slick.
(Gloeoeapssa) o.-2-2 2222 bolle See Anacystis.
Gloeotystist oes MEGS eee iene Ln SAR, Sines eect ee a ie Septic sce el i os Bees es ee
Gloeounichia 2s ee Blue preemie aaa oe leary ee Giaesye oe Ore ee oe
Gomphosphaerian 20 22 Blue-green_____-- pee a Grassy. 2) es GiRsey es eee ee Sweete.: oi
animes See Wlagellateccs 3222 0G Ste a eee Wishy oe.) 6 Ge Sa gn ee Uc ee ae
EDVOTOGIOLYON: 25k io io REPT se a i ee Soe eae SED bi Ge ss  e  s  ee e
Mallomonas:= <2 2802 2s oe Blapellatecs tess Violét2e 2 ee ses WishvAc tee ee eS ee :
MielOsiTaiws 0 eee MD YSTOMI os es ae ea Geranitine: 2. 22. ea eas Musiy ee ee Slick.
Meridion® 22.8222 oe DIatO Mi spe eur ic ee oie 2 eer a ed ee Nas Spicy eis ees ee
@viliorocyetis) oto 2 ee See Anacystis.
ates soe ss es MECH Ss hee ee ae Grassy 3 222 ee Grassy, septic____-_----- Bitten: 223 <!
Waster 52 eee Blué-preensse oe es Musty. 02 oo ee eee Septic gs oi ec ee ae Se oe ee
Geailanora. |. fo ee ee IBlvesereens ee Grassy. {2222 San goes Mirstyispicycc. a2 ieee
Huon e vs es ae Diagellate 0 tn Ee ae cee Hishiy 2. OS ei ee ee eee
Medicis sos ee (Gere ae hee ee eee Grassy os eee ee
memcinin ke ale Mlagellatesc: Se ss oS Gucimber 2 ee Ris hiv ce eee nae een a eee ae
IGUROMIONIA 5 foes Se MOAGOMIE So eer ee re ot A eee ee Mishyeo 24 Sen  eeeee
ivan ye ee Blue-green: 2222 Gibassy 238 Soo ee 2 ces Musty2. Sh ee
BESMeAPeINUG! ae Greenman Grassy.) ose ee ee
pInOpVnee oo ieee Great are ee ee eae So es ee Grassy eo NG A ee ee
PHeiUeS pr. 22 eo So ee Green eee: ie Ce yc rae as 2 es ee Grassyc8 = ee ee ;
Stephanodiscus__---______--- Diatome sso seer pee Geranium 224s ee Mishyc 059202 oe ee ee Slick.
edna sie re ee ee ee Dintomenes ote 7s 2 Grassy 600s eee Musty: (22s .35 030) Ge ee Slick
By Unters aoe a Hlagellates 22. oe Cucumber, muskmelon, Rishy2 5 Se ee iiber ieee Dry, <
spicy. metallic,
i slick.
Mabolisnines aes Dato. eo ese eee Gersnime eee Wish 2 Jancis ha Se ee ae ee
‘Dribonemins ee MGGIiC et en ee ne Pc a ets eo Mishy 23 (ech ces ea ee ee
CUroplenn) see 2s oh. eS See Uroglenopsis. ;
Wroglenopsiss. 6. 6, Ses Blageliates: 2-5 ose. Cucumbers: hors st Wighiy: ie es ee a |e ee a Slick.
OU N rise eee ee Ginnie alone ie Nate Sere ie Oe ec gles ual ae Grassy (Nigel RAN Si tc Welt | Pee WE aay et OR
WOlV OMS ge Riggellanced wos Voss ae Bishi ocak tone ieee Wishy.f 2 202 Sees sees ee

 

 

 

 

 

 
''Taste and Odor Algae

21

 

species of algae produce tastes and odors in water and under
what conditions this takes place. Suspected forms are ob-
tained in pure growth cultures for this work (13) and chem-
ical analyses are being made of their products and of various
organic wastes which have odor (14). Additional research
is being directed toward the finding of algicides which are
sufficiently selective to destroy certain taste and odor algae
without at the same time being wasted on nonoffending types
(15). The relationship of actinomycetes to earthy seat in
water is also being studied.

The following statement by Laughlin (16) is an expres-
sion of the emphasis which the control of taste and odor
problems must be given in modern programs for water treat-
ment: “It is one of the basic duties and responsibilities of
the water purification plant operator to furnish his public
with a palatable water 24 hours a day. * * * The presence
of any objectionable odor may cause the consumer to go to
a more palatable but unsafe water supply. Therefore, the
importance of producing a palatable water cannot be
overemphasized.”

REFERENCES

1. Central Missouri River water quality investigation for 1955. U.S.
Dept.. Health, Education and Welfare, Public Health Service,
Water Supply and Water Pollution Control Section, Region 6,
Kansas City, Mo.,50p. (Mimeographed). 1956.

2. ¢ Control of odor and taste in water supplies. E. A. Sigworth.
Jour. Amer. Water Wks. Assn. 49: 1507-1521. 1957.

3. The role of actinomycetes in producing earthy tastes and smells
in potable water. B. A. Adams. Rept. of Public Wks., Roads

10.

11.

12.

13.

14.

“15.

16.

. The microscopy of drinking water.

. Tastes and odor control.

. The relation of taste and odor to flavor.

and Transport Congress. Paper No. 4. London, England.
1933.

. Actinomycetes may cause tastes and odors in water supplies.

J. K. Silvey and A. W. Roach. Public Wks. Mag. 87: 103-106,
210, 212. 1956.

Ed. 4. G. C. Whipple, G. M.
Fair, and M. C. Whipple. J. Wiley and Sons, N.Y., 586 p.

With 19 color plates. 1948.

. Standard methods for the examination of water, sewage, and

industrial wastes. Ed. 10. Amer. Public Health Assn., N.Y.,
522 p. 1955.

G. E. Symons.
1956.

Water and Sewage Wks.
1908 : 307-310, 348-355.
C. W. Aman. Taste
and Odor Control Jour. 21 (No. 10) :1-4. 1955.

. Treating algae under the ice at Westfield, Mass. EH. A. Snow and

A. Iantosea.
1952.

Microscopic organisms in reservoirs. C. A. Cofoid. Jour. Amer.
Water Wks. Assn. 10: 183-191. 1923.

Fishy odor in water caused by Dinobryon. J. R. Baylis. Pure
Water, Chicago, Hl. South District Filtration Plant, 3: 128-150.
1951.

Review of microorganisms in water supplies. S. O. Swartz.
Jour. New England Water Wks. Assn. 69: 217-227. 1955.

The use of algal cultures in experiments concerned with water
supply problems. C. M. Palmer and T. E. Maloney. Butler
Univ. Bot. Stud. 11: 87-90. 1953.

Drinking water taste and odor correlation with organic chemical
content. F.M. Middleton, G. Wallace and A. A. Rosen. Indust.
Eng. Chem. 48 : 268-274. 1956.

Evaluation of new algicides for water supply purposes. C. M.
Palmer. Jour. Amer. Water Wks. Assn. 48: 1133-1137. 1956.

Palatable level with the threshold odor test. H. F. Laughlin.
Taste and Odor Control Jour. 20 (No. 8) :1-4. 1954.

Jour. New England Water Wks. Assn. 66: 47-54.
''CHAPTER V

FILTER CLOGGING ALGAE

AS WATER passes through a sand filter in the treatment
plant the spaces between the grains of sand become filled
with colloidal and solid particles which had been dispersed
in the water. If the raw water comes from a surface supply
such as a reservoir, lake, or stream, the algae which are in-
variably present will be well represented in the material
collected by the sand filter. They are frequently the pri-
mary causes for the clogging of the filter.

In most places the algae and other particulate materials
are sufficiently numerous throughout most of the year to
require that the water be treated by coagulation and sedi-
mentation previous to filtration through sand. Without
this preliminary treatment the filter would clog so rapidly
that it would be uneconomical to use, except when relatively
clear water is available. Certain plants in California and
in Canada have been using the rapid sand filter without
prior coagulation at least during portions of the year (1).

Efficient coagulation and sedimentation may remove up to
90 or 95 percent of the algae from the water. The algae
remaining in the water may still be sufficient to cause grad-
ual or even rapid loss of head in the sand filter. The
clogged filter must then be taken out of service and cleaned
or backwashed. Normal filter runs commonly extend for
from 30 to 100 hours before cleaning is required, while short
filter runs, caused by the presence of algae, are even less than
10 hours in length (2). In extreme cases the clogging may
recur so frequently that the amount of water required to
backwash the filter is greater than the amount of filtered
water which reaches the distribution system. Thus the
presence of algae can slow up the process of water treatment
and add materially to its cost.

CLOGGING PROCESSES

Both the slow and rapid sand filters may become clogged
with algae, but in the former the algae and other aquatic
microorganisms may play a useful part in the treatment
process. They form a loose, slimy layer over the surface of
the sand and act as a filter. The algae in this layer release
oxygen during photosynthesis, and the oxygen in turn is
utilized by aerobic saprophytic bacteria, fungi, and protozoa
which establish themselves in and on the filter. This permits
the decomposition or stabilization of the organic material that
was present in the raw water. Diatoms, however, due to their
rigid walls, may do more harm than good by speeding the
clogging of the filter, but it has been possible to use slow sand
filters when diatoms have put rapid filters out of commission
(3). The water that has passed through a slow sand filter is
relatively free of bacteria, algae, and other organisms as well
as of dead organic matter.

22

It is not yet fully understood why certain algae are more
effective than others in reducing the movement of water
through the filters. Ability to develop in large numbers
is certainly one essential. The rigid wall, such as is found
in the diatoms, the copious mucilaginous material around
the cells as in the case of Palmelia, and the tendency to
form flakes or a network of strands, as in Fragilaria and
Tribonema are other factors. :

Diatoms are present during all seasons of the year and
are by far the most important group of organisms which
clog filters. The most serious offenders are Asterionella,
Fragilaria, Tabellaria, and Synedra. Other diatoms that
may occasionally cause this trouble include Vavicula, Cyclo-
tella, Diatoma, and Cymbella, all of which are illustrated on
plate 2. The rigid cell wall of diatoms is composed prin-
cipally of silica and is not subject to decomposition. There-
fore, even though the diatoms may die off rapidly on the
surface of the filter, their silica walls remain to plug the
pores in the sand.

In England a relatively pure growth of Fragilaria de-
veloped in a reservoir to the extent that it was necessary
to remove huge quantities of this diatom at the water treat-
ment plant. Counts of another filter clogging diatom, As-
tertonella, indicated that the organism has reached a density
as high as 20,000 per ml. (4).

In Chicago, when the water to be filtered contained ap-
proximately 700 microorganisms per ml., principally Tabdel-
laria and Fragilaria, the filter runs were only 4.5 hours.
Three days later, when the count was down to approxi-
mately 100 per ml., the filter run increased to 41 hours (5).
In Washington, D.C., filter runs were reduced from an
average of 50 hours to less than 1 hour due to the sudden
influx of the diatom Synedra, which had a concentration in
the raw water reaching 4,800 cells per ml. (6).

The filter clogging blue-green algae are represented on
plate 2 by Anacystis (Chroococcus type), Rivularia, Ana-
baena, and three species of Oscillatoria. Anabaena is
known to have caused filter trouble in Illinois and Min-
nesota while Oscéllatoria is one of the offenders in Switzer-
land. Dinobryon and Trachelomonas are pigmented flag-
ellates, the former being common in the Great Lakes and
in the soft waters of the eastern United States. Chlorella,
Palmella, Spirogyra, and the desmid, Clostertwm, are green
algae while 7'7ibonema is a yellow-green filament. Chilo-
rella is the alga which has given trouble by clogging filters
made of glass wool. In addition, it grows on the inner
surfaces of the glass bottle in water coolers and in water
lines constructed of plastic tubing, when these have been ex-
posed to light. In the tropics and warm temperate zone,
''Filter Clogging Algae 23

 

the filamentous green algae are often the common offenders
in clogging of sand filters.

Forty-three of the more important filter clogging algae are
listed alphabetically under their major groups in table 6,
below. Twenty-two of these are illustrated in color on
plate 2, while a few of the remaining forms are to be found
on the other plates as indicated in the table.

Table 6.—Filter Clogging Algae

Group and Algae Plate
Blue-Green Algae (Myxophyceae):
Anabaena flos-aquae 2
Anacystis dimidiata (Chroococcus turgidus) 2

Gloeotrichia echinulata
Oscillatoria amphibia

Oscillatoria chalybea 2
Oscillatoria ornata
Oscillatoria princeps 2

Oscillatoria pseudogeminata
Oscillatoria rubescens

Oscillatoria splendida 2

Rivularia dura 2
Green and Yellow-Green Algae (nonmotile Chlorophyceae, etc.):

Chlorella pyrenoidosa 2

Cladophora aegagropila

Closterium moniliferum 2

Dichotomosiphon tuberosus
Dictyosphaerium pulchellum
Hydrodictyon reticulatum 1
Mougeotia sphaerocarpa
Palmella mucosa
Spirogyra porticalis
Tribonema bombycinum
Ulothrix variabilis
Zygnema insigne

Diatoms (Bacillariophyceae):
Asterionella formosa
Cyclotella meneghiniana
Cymbella ventricosa
Diatoma vulgare
Fragilaria crotonensis
Melosira granulata
Melosira varians
Navicula graciloides
Navicula lanceolata
Nitzschia palea
Stephanodiscus binderanus
Stephanodiscus hantzschii
Synedra acus
Synedra acus var. radians (S. delicatissima)
Synedra pulchella
Tabellaria fenestrata
Tabellaria flocculosa

Pigmented Flagellates (Chrysophyceae, etc.):
Dinobryon sertularia 2
Peridinium wisconsinense
Trachelomonas crebea 2

No w NY NNNNNWLd wNnwrn

Noe

Most of the microscopic organisms present in water that is
passing through a rapid sand filter generally will be caught
in the top one-half inch of the sand. This is particularly
the case when the organisms are abundant in the water. A
few of the organisms will penetrate deeper into the filter bed

while others disintegrate quickly as they come in contact with
the sand. The longer the filter run the greater the percentage
of organisms that will penetrate below the top one-half inch.

In Chicago, a study was made of the numbers of certain
diatoms that were caught on the surface of rapid sand filters.
The samples were collected immediately before the filters
were backwashed. During 1 year of this study, 7abellaria
ranged in numbers from 496,000 to 936,000 per square inch
of filter surface in April, and from 1,824,000 to 8,016,000 in
November. In contrast, the range for Ifelosira was from
784,000 to 2,624,000 in April, and only 16,000 to 416,000 in
November (7).

The relationships of algae to sand filters involve also the
problem caused by passage of certain algae through both
rapid and slow filters and into the treated water. A number
of the same algae that can clog filters have at other times
been offenders in penetrating them. Algae that have passed
through rapid filters include Synedra and Oscillatoria and
through slow filters, Chlamydomonas, Euglena, Navicula,
Niteschia, Phacus, and Trachelomonas (8). The ease with
which the algae penetrate depends upon several factors, the
principal ones being the rate of flow, the grade of sand used,
and the type of organism. Very minute algae and flagellates
penetrate with greater facility than other types. When the
penetration is slow, it may be a few hours before the algae
reach the underdrains. Frequent backwashing, even when
the filter is not clogged will tend to remove the algae and
reduce the number that would reach the filtered water.

REFERENCES

1. The effects of algae in water seoutien D. H. Matheson. Inter-
national Water Supply Assn., General Rept. to 2d Congress,
Paris, France, 82 p. 1952.

2. Algae control at Danbury, Connecticut. E. A. Tarlton. Jour. New
England Water Wks. Assn. 63: 165-174. 1949.

3. Interesting experiences with microorganisms in the Washington
water supply. G. E. Harrington. Proc. 9th Ann. Conf. Md.-Del.
Water and Sewerage Assn., p. 74-99. 1935.

4, Freshwater biology and water supply in Britain. W. H. Pearsall,
A. ©. Gardiner and F. Greenshields. Freshwater’ Biolog. Assn.
of the British Empire, Publ. No. 11,90 p. 1946.

5. Effect of microorganisms on lengths of filter runs. J. R. Baylis.
Water Wks. Eng. 108: 127-128, 158. 1955.

6. The significance of microorganisms in plant design. C. J. Lauter.
Proce. 11th Ann. Conf. Md.-Del. Water and Sewerage Assn.,
p. 67-74. 1987.

7. Microorganisms that have caused trouble in the Chicago water
system. J. R. Baylis. Pure Water, Dept. of Water and Sewers,
Chicago, Il. 9: 47-74. 1957.

8. The biological examination of water. A. T. Hobbs. Chapt. 18,
p. 716-758 in his Manual of British water supply practice.
Ed. 2. H. Heffer and Sons, Ltd., Cambridge, England. 1954.
'' 

 

 

 

 
''Color Plates 1 to 6
''T

ALGAE IMPORTANT IN WATER SUPPLIES

TASTE AND ODOR ALGAE

    
  
    
      

ANABAENA

  
    

ANACYSTIS
“pe
‘

 

te, Woes oe
i PZ UROGLENOPSIS

SYNEDRA

PERIDINIUM

CERATIUM

GOMPHOSPHAERIA
NITELLA _
''PLATE 1

TASTE AND ODOR ALGAE

Species Names

Anabaena planctonica
Anacystis cyanea
Aphanizomenon flos-aquae
Asterionella gracillima
Ceratium hirundinella
Dinobryon divergens
Gomphosphaeria lacustris, kuetzingianum type
Hydrodictyon reticulatum
Mallomonas caudata
Nitella gracilis

Pandorina morum
Peridinium cinctum
Staurastrum paradoxum
Synedra ulna

Synura uvella

Tabellaria fenestrata
Uroglenopsis americana

Volvox aureus

Linear
Magnifications

250
250
250
250

Chem
''FILTER CLOGGING ALGAE

ANACYSTIS

DINOBRYON

TRIBONEMA
CHLORELLA

SYNEDRA

TRACHELOMONAS

FRAGILARIA

ANABAENA
DIATOMA

 

PLATE. 2
''PLATE 2

FILTER CLOGGING ALGAE

Linear

Species Names Magnifications
Anabaena flos-aquae 500
Anacystis dimidiata 1000
Asterionella formosa 1000
Chlorella pyrenoidosa 5000
Closterium moniliferum 250
Cyclotella meneghiniana 1500
Cymbella ventricosa 1500
Diatoma vulgare 1500
Dinobryon sertularia 1500
Fragilaria crotonensis 1000
Melosira granulata 1000
Navicula graciloides _ 1500
Oseillatoria princeps (top) 250
Oscillatoria chalybea (middle) 250
Oscillatoria splendida (bottom) 500
Palmella mucosa 1000
Rivularia dura 250
Spirogyra porticalis 125
Synedra acus 500
Tabellaria flocculosa | 1500
Trachelomonas crebea 1500

Tribonema bombycinum ; 500
''POLLUTED WATER ALGAE

   
    
       
     
    

AGMENELLUM

CARTERIA

LEPOCINCLIS

PYROBOTRYS NITZSCHIA

EUGLENA
TETRAEDRON

OSCILLATORIA

PHACUS

CHLOROGONIUM

CHLORELLA

  
 
 

GOMPHONEMA
STIGEOCLONIUM

   
  

ANACYSTIS

ARTHROSPIRA

LYNGBYA

   
   

CHLAMYDOMONAS

PLATES
''PLATE 3

POLLUTED WATER ALGAE

Linear

Species Names Magnifications
Agmenellum quadriduplicatum, tenuissima type 1000
Anabaena constricta 500
Anacystis montana 1000
Arthrospira jenneri 1000
Carteria multifilis 2000
Chlamydomonas reinhardi 1500
Chlorella vulgaris 2000
Chlorococcum humicola 1000
Chlorogonium euchlorum 1500
Euglena viridis 1000
Gomphonema parvulum 3000
Lepocinclis texta 500
Lyngbya digueti | 1000
Nitzschia palea 2000
Oscillatoria chlorina (top) 1000
Oscillatoria putrida (middle) 1000
Oscillatoria lauterbornii (bottom) 1000
Phacus pyrum 1500
Phormidium autumnale 500
Pyrobotrys stellata 1500
Spirogyra communis 250
Stigeoclonium tenue 500

Tetraedron muticum 1500
''CLEAN WATER ALGAE

       
    
    
    
   
   
   
    
 
    

RHIZOCLONIUM CLADOPHORA

f)
PINNULARIA

CYCLOTELLA

RHODOMONAS

ANKISTRODESMUS

COCCOCHLORIS

CALOTHRIX

MERIDION

ENTOPHYSALIS

CHROMULINA

PHACOTUS

LEMANEA

    

MICGROCOLEUS
COCCONEIS

PLATE 4
''PLATE 4

CLEAN WATER ALGAE

Linear

Species Names Magnifications
Agmenellum quadriduplicatum, glauca type 250
Ankistrodesmus falcatus var. acicularis 1000
Calothrix parietina 500
Chromulina rosanoffi 4000
Chrysococcus rufescens 4000
Cladophora glomerata 100
Coccochloris stagnina 1000
Cocconeis placentula 1000
Cyclotella bodanica 500
Entophysalis lemaniae 1500
Hildenbrandia rivularis 500
Lemanea annulata 1
Meridion circulare 1000
Micrasterias truncata 250
Microcoleus subtorulosus 500
Navicula gracilis 1000
Phacotus lenticularis 2000
Pinnularia nobilis 250
Rhizoclonium hieroglyphicum ' 250
Rhodomonas lacustris : 3000
Staurastrum punctulatum 1000
Surirella splendida 500

Ulothrix aequalis 250

 
''PLANKTON AND OTHER SURFACE WATER ALGAE

      
   
   
 
     
  
    
   
  

FRAGILARIA

   
  
   

NODULARIA

COELASTRUM

EUGLENA

GOMPHOSPHAERIA

MICRACTINIUM

MOUGEOTIA

 

BOTRYOCOCCUS

OOCYSTIS

SCENEDESMUS

GONIUM

DESMIDIUM

SPHAEROCYSTIS

  
    

    

ZYGNEMA

STAURONEIS EUDORINA

PEDIASTRUM

PLATES
''PLATE 5

PLANKTON AND OTHER SURFACE
WATER ALGAE

Linear

Species Names Magnifications
Actinastrum gracillimum 1000
Botryococcus braunii 1000
Coelastrum microporum 500
Cylindrospermum stagnale 250
Desmidium grevillei 250
Euastrum oblongum 500
Eudorina elegans 250
Euglena gracilis 1000
Fragilaria capucina 1000
Gomphosphaeria aponina 1500
Gonium pectorale 500
Micractinium pusillum 1000
Mougeotia scalaris 250
Nodularia spumigena 500
Oocystis borgei 1000
Pediastrum boryanum 125
Phacus pleuronectes 500
Scenedesmus quadricauda 1000
Sphaerocystis schroeteri 500
Stauroneis phoenicenteron 500
Stephanodiscus hantzschii 1000.

Zygnema sterile 250
''ALGAE GROWING ON RESERVOIR WALLS

PHORMIDIUM

 

ULOTHRIX

GOMPHONEMA

TETRASPORA

AUDOUINELLA

BULBOCHAETE

MIGROSPORA

CYMBELLA

PHYTOCONIS

OEDOGONIUM
DRAPARNALDIA

CHAETOPHORA

PLATE. 6
''PLATE 6

ALGAE GROWING ON
RESERVOIR WALLS

Linear

Species names magnifications
Achnanthes microcephala 1500
Audouinella violacea 250
Batrachospermum moniliforme 3
Bulbochaete insignis 125
Chaetophora elegans 250
Chara globularis 4
Cladophora crispata 125
Compsopogon coeruleus 125
Cymbella prostrata 250
Draparnaldia glomerata 125
Gomphonema geminatum 250
Lyngbya lagerheimii 1000
Microspora amoena 250
Oedogonium suecicum 500
Phormidium uncinatum 250
Phytoconis botryoides 1000
Stigeoclonium lubricum 250
Tetraspora gelatinosa 125
Tolypothrix tenuis 500
Ulothrix zonata 250
Vaucheria sessilis 125

496792 O-59—4
''CHAPTER VI

POLLUTED WATER ALGAE

WATER CONTAINING one or more of various types of
“impurities” may be said to be “polluted.” The term pol-
lution is usually restricted to situations in which the con-
dition is considered potentially harmful to human health
or capable of interfering seriously with the use of the
water or its immediate environment. Most of the infor-
mation at present available on algae in relation to polluted
water is limited to water containing treated or untreated
domestic sewage and closely related organic wastes. The
following account, therefore, will deal primarily with this
type of water pollution.

After domestic sewage or effluent has polluted a body of
water such as a stream, the algae present react in a manner
that has come to be recognized as of considerable im-
portance. During the process of natural purification, the
algae oxygenate the water, and also utilize byproducts of
the purification process. The kinds and numbers of algae
and other organisms in the polluted portion of a stream are
different from those present in the unpolluted portion above
the sewer outlet. As the sewage goes through stages of de-
composition in the stream, the numbers and kinds of micro-
organisms continue to change until eventually the aquatic
flora and fauna in the purified water become somewhat sim-
ilar to those found above the point of pollution. The algae
represent a conspicuous and significant group in this con-
tinuously changing population in a stream. The variation
in the algal population at different points or under different
conditions of pollution constitutes one of the indices that can
be.applied to any desired location in the stream to determine
the presence or absence of domestic sewage or other putres-
cible wastes, or to measure the sere of recovery from
pollution with these wastes.

It appears evident to many workers that particular genera
or even species of algae, when considered alone, are not re-
liable indicators of organic pollution. However, when a
number of kinds of algae are considered as a community,
that group may be a reliable index. Lists of algae and
other organisms indicative of the various pollution zones in
a stream have been compiled, including those by Kolkwitz
(1), Liebmann (2), and Whipple, Fair, and Whipple (3).

Emphasis in this account is placed on the algae which
various workers have found to be present and relatively
prominent or persistent in the polysaprobic and alpha-meso-
saprobic zones of polluted streams. These names for the
zones, however, have been used by comparatively few
workers who have reported on sewage-tolerant algae, and
their findings have had to be interpreted in such a way as
to combine the information from the many sources.

38

Reports of more than 50 workers have been examined for
names of algae commonly found in waters containing a high
concentration of organic wastes. From these, a total of
more than 500 species of algae has been compiled by the
writer (4). Forty-seven of the more important species
from this group have been selected and are given in table 7,
and 23 of these pollution algae are illustrated in color on
plate 3.

Table 7.—Pollution Algae—Algae Common in Organically

Enriched Areas

Group and Algae Plate or Figure

Blue-Green Algae (Myxophyceae) :
Agmenellum quadriduplicatum, tenuissima type
Anabaena constricta
Anacystis montana
Arthrospira jenneri
Lyngbya digueti
Oscillatoria chalybea
Oscillatoria chlorina
Oscillatoria formosa
Oscillatoria lauterbornii
Oscillatoria limosa
Oscillatoria princeps
Oscillatoria putrida
Oscillatoria tenuis Fig.
Phormidium autumnale
Phormidium uncinatum

Green Algae (nonmotile Chlorophyceae) :
Chlorella pyrenoidosa
Chlorella vulgaris
Chlorococcum humicola
Scenedesmus quadricauda
Spirogyra communis
Stichococcus bacillaris
Stigeoclonium tenue
Tetraedron muticum

WWWWWwWWwW

w

Fig. 29

30

waw wr Ow" wn’

Www

Diatoms (Bacillariophyceae) :
Gomphonema parvulum
Hantzschia amphioxys
Melosira varians
Navicula cryptocephala
Nitzschia acicularis
Nitzschia palea 3
Surirella ovata

Flagellates (Euglenophyceae, Volvocales of Chlorophyceae):
Carteria multifilis
Chlamydomonas reinhardi
Chlorogonium euchlorum
Cryptoglena pigra
Euglena agilis
Euglena deses
Euglena gracilis 5
Euglena oxyuris
Euglena polymorpha
Euglena viridis
Lepocinclis ovum
Lepocinclis texta
Pandorina morum
Phacus pyrum
Pyrobotrys gracilis
Pyrobotrys stellata
Spondylomorum quaternarium

w

Www

Oo Wew Ww
''Polluted Water Algae 39

 

Many genera of algae include certain species that are
tolerant of organic enrichment and others that are not. This
is particularly true of Chlamydomonas, Luglena, Navicula,
Oscillatoria, Phormidium, and Synedra. Tn a few instances
the same thing may be true also for strains or varieties of
a species. For example, Fjerdingstad (5) claims that there
are two separate strains of the species Ulothrix zonata,
(fig. 29) the pollution type and the pure water type.

  

Figure 29.—Ulothrix zonata, vegetative filament and stages in spore
production. Its two strains react differently to pollution.

 

 

 

 

 

  

 

 

 

TITLE Pree
‘ a
et.

Figure 30.—Oscillatoria limosa.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IM

 

 

 

 

 

ID

Figure 32.—Oscillatoria princeps.

 

LTR

CLL Ee

FPEPREEED TSE ED

Figure 33.—Phormidium uncinatum.

496792 O-59—5

Included in the group of pollution algae are some forms
of unusual interest. Euglena viridis, Nitzschia palea, Os-
cillatoria limosa (fig. 30) and Oscillatoria tenuis (fig. 31)
have been listed by workers more often than any other spe-
cies as reliable indicators of organic pollution (5). Next
in order are Arthrospira jenneri, Stigeoclonium tenue, Bu-
glena gracilis, and Chlorella vulgaris. Anabaena constricta,
Chlorella vulgaris, and Fuglena viridis are encountered also
on sludge or in retention basins of sewage treatment plants.
Chlorella is the alga that grows readily in artificial culture
media and is being used in a number of laboratories to deter-
mine the feasibility of producing algae on a large scale for
food, animal feed, and other products. Two additional
blue-green algae tolerant of organic enrichment are Oscilla-
toria princeps (fig. 32) and Phormidium uncinatum (fig.
33).

The blue-green algae and the flagellates are the algal
groups most frequently encountered in the portion of a
stream containing organic wastes. Not all representatives
of the “blue-green” algae are actually blue-green in color
For example, the three species of Oscillatoria illustrated on
plate 3 tend to be decidedly yellow-green, although they be-
long to the above group. The flagellate green alga, Chla-
mydomonas, is one of the very common organisms in water.
There being a large number of species of this genus and
also chlamydomonad stages of other algae, workers gen-
erally have not identified the particular species of this genus
which they have encountered in polluted water. It is prob-
able that there are a number of species other than the
Chlamydomonas reinhardi shown on plate 3 which could
be listed as algae indicative of organic pollution.

Many of the nonswimming green algae with rounded cells
are difficult to identify correctly and often have been mis-
takenly labeled Protococcus (name now changed to Phyto-
conis), a type which is common on moist surfaces of tree
trunks and which is attached and not normally planktonic.
The two genera of green algae with rounded cells that are
included here as pollution algae are Chlorella and C)oro-
coccum, both of which are illustrated on plate 3.

ALGAE AND SEWAGE TREATMENT

Treatment and disposal of sewage are an essential process
in all large cities and in an increasing number of smaller
communities. Extensive treatment plants are equipped with
settling basins, gravel beds, large and complicated machin-
ery, and well-equipped laboratories. The actual decomposi-
tion of the sewage, however, is almost invariably brought
about by microorganisms. Chemical or physical methods
such as the use of strong acids or drying and burning are
generally too expensive in comparison with the biological
treatment.

In this biological process several types of microorganisms
are frequently involved. The treatment plant operation
consists primarily of making conditions ideal for the rapid
development of bacteria, molds, protozoa, and rotifers, since
it is through the activities of these microorganisms that the
''‘ 40 ALGAE IN WATER SUPPLIES

 

sewage is changed from an offensive to an inoffensive con-
dition (6).

Recently algae have received more attention for the part
they are able to play in sewage treatment. In sewage sta-
bilization ponds or lagoons, algae can be utilized for the
production of oxygen essential to the growth of the bacteria
and other organisms that break down the organic wastes.
With algae it is possible to support immense populations of
aerobic bacteria, and the sewage stabilization process is
greatly accelerated. Large open shallow basins or waste
stabilization ponds are required in order that light will be
available through the liquid to stimulate algal growth and
activity. Certain kinds of algae are able to grow in the
presence of a high concentration of sewage and these may
be stimulated to grow and multiply very rapidly. It ap-
pears that only young algal cells will produce large quanti-
ties of oxygen, thus making it desirable that the multiplica-
tion of additional young cells be kept up as a continuous
process at the sewage treatment plant. The sewage is emp-
tied into the shallow open basin or lagoon and allowed to
move slowly through it while the algae multiply rapidly and
produce the oxygen. The algae which develop in large num-
bers in sewage stabilization ponds and lagoons are the same
kinds that are present in the portions of streams which are
polluted with organic wastes (7).

The massive growths of algae developed in sewage sta-
bilization ponds and lagoons may eventually become a new

source of fertilizer, vitamins, animal feed, and other prod-
ucts for commerce. Algae also are potentially valuable as
efficient users of the nutrient salts resulting from decom-
position of sewage, so that algae might supplement the land
plants grown on farms in producing many kinds of organic
products useful to man. Thus the pollution algae may be-
come useful not only as indicators and as purifiers but as
producers.

REFERENCES

1. Oekologie der Saprobien. Uber die Bezeihungen der Wasserorgan-
ismen zur Umwelt. R. Kolkwitz. Schriftenreihe des Vereins fiir
Wasser-, Boden-, und Lufthygiene. No. 4. 64 p. 1950.

2. Handbuch der Frischwasser- und Abwasserbiologie. Band 1. H.
Liebmann. R. Oldenbourg, Miinchen, Germany, 539 p. 1951.

3. The microscopy of drinking water. Ed. 4. G. C. Whipple, G. M.
Fair, and M. C. Whipple. J. Wiley and Sons, N.Y., 586 p. With
19 color plates. 1948.

4. Algae as biological indicators of pollution. C. M. Palmer. In Bio-
logical problems in water pollution. Dept. Health, Education,
and Welfare, Public Health Service, Robert A. Taft San. Eng.
Center, Cincinnati, Ohio, p. 60-69. 1957.

5. The microflora of the River Molleaa with special reference to the
relation of the benthal algae to pollution. E. Fjerdingstad.
Folia Limnologica Scandinavica, No. 5, 123 p. 1950.

6. Microbiology of water and sewage. P. L. Gainey and T. H. Lord.
Prentice-Hall, Inc., N.Y., 480 p. 1952. ‘

7. A systematic study of the algae of sewage oxidation ponds. P. C.
Silva and G. F. Papenfuss. California State Water Pollution
Control Board. Publication No. 7, 34 p. 1953.
''CHAPTER VII

CLEAN WATER ALGAE

CLEAN WATER organisms are those found in water which
is free of sewage or other organic enrichment due to waste
discharge. The clean water may be that portion of streams
above sewage outlets or far enough downstream for the sew-
age to have been reduced to relatively inoffensive salts and
other simple compounds. Most of these products of sewage
decomposition are nutrients and will stimulate organisms
such as algae to grow much more profusely than they do in
the stream above the sewage outlet, where nutrients are
limited in quantity. The kinds of algae in the clean waters
upstream and downstream tend to be similar, however.

Large numbers of algae will be found in the section of the
stream often called the “recovery zone” which contains par-
tially decomposed sewage. It is difficult to select particular
algae as the best indicators of the downstream clean water
zone, since it is adjacent to the “recovery zone” where purifi-
cation is still in progress. As with the polluted water forms,
it is more satisfactory to emphasize the presence or absence
of several of the clean water algae rather than of any one
species alone in defining the clean water zone.

Forty-six species have been selected as representative of
the clean water algae and are listed in table 8. Twenty-
three of these species are illustrated in color on plate 4. The
group includes several diatoms, several brown to reddish
flagellates, certain greens and blue-greens, and a few fresh-
water red algae of the class Rhodophyceae. A number of
them, particularly the flagellates, are very minute and appear
small even under the high power of a compound microscope,
but they frequently are better indicators of clean water than
many larger algae that may be mixed with them. However,
a few of the larger forms are also useful in indicating the
condition of the water and are represented by certain species
of Cladophora, Rhizoclonium, Lemanea, and others.

Some of the clean water algae are planktonic, while others
are attached to rocks or other material at the bottom or sides
of the stream like Calothrix parietina (fig. 34). The blue-

 

Figure 34.—Calothrix parietina is attached to logs and stones in
running water.

green alga Entophysalis lemaniae (formerly called Chamae-
siphon incrustans) and the diatom Cocconeis placentula are
epiphytic, i.e., algae which grow attached to the surface of
other plants in the water. :

Several of the genera with clean water species include also
other species whose reaction to sewage pollution is different
from the clean water forms. Both the pollution and clean
water groups are represented by contrasting species of
Navicula, Niteschia, Phormidium, Agmenellum, Surirella,
Ulothrix, and Euglena. In these same genera, as well as in
Pinnularia, Cyclotella, and Cladophora, there are also species
considered to be indifferent to sewage. Identification to spe-
cies is, therefore, essential for any accurate differentiation
of pollution zones through the use of algae as indicator
organisms.

Clean water algae are commonly listed by some writers as
typical of the oligosaprobic zone, which is defined as the “zone
of cleaner water” where mineralization has been completed
(1). However, from the standpoint of sanitation this zone of
water is not likely to be clean or pure since it undoubtedly is
not free of bacteria and viruses of intestinal origin. The
oligosaprobic zone does not have a fixed location nor length
since the distance required for stream purification varies ac-
cording to temperature, the pollution load, the rate of flow,
and other factors. The limited flora and fauna of springs
and pure mountain streams are placed in a separate group
known as the katarobic (1). More extensive lists of organ-
isms considered characteristic of the various pollution zones
have been published recently by Butcher (2), Kolkwitz (3),
Lackey (4), Liebmann (5), Patrick (6), and others.

Butcher (2) claimed that a community composed of the
diatom Cocconeis and the blue-green alga EH’ntophysalis
(listed as Chamaesiphon) is present in the portion of the
stream which has returned to normal following purification
of a polluted condition. Kolkwitz (8) lists as oligosaprobic
61 diatoms, 42 green algae, 41 pigmented flagellates, 23 blue-
green algae, and 5 red algae. Lackey (4) found 77 species
of planktonic algae in the clean water portion of a small
stream, 40 of which were absent in the polluted area a short
distance downstream. Liebmann (5) emphasized particu-
larly the following algae as characteristic of the oligosa-
probic zone: The flagellate Chromulina rosanoffi in slow
flowing water, and the flagellate Afallomonas caudata, the
green algae Ulothria zonata and Microspora amoena, and the
red algae Lemanea annulata and Batrachospermum vagum in
rapidly flowing water. Patrick (6) listed Amphora ovalis
and Gyrosigma attenuatum as examples of diatoms that
seemed to be adversely affected by high organic content of
water. Brinley (7) reported that the presence of the flagel-

41
''42 ALGAE IN WATER SUPPLIES

 

late algae Chrysococcus and Cryptomonas in large numbers
indicated that the decomposition of organic matter in the
stream has been completed.

Table 8.—Clean Water Algae
Plate or
Group and Algae Figure
Blue-Green Algae (Myxophyceae) :
Agmenellum quadriduplicatum, glauca type
Calothrix parietina
Coccochloris stagnina
Entophysalis lemaniae
Microcoleus subtorulosus
Phormidium inundatum

Green Algae (Nonmotile Chlorophyceae) :
Ankistrodesmus falcatus, var. acicularis
Bulbochaete mirabilis
Chaetopeltis megalocystis
Cladophora glomerata
Draparnaldia plumosa
Euastrum oblongum
Gloeococcus schroeteri
Micrasterias truncata
Rhizoclonium hieroglyphicum
Staurastrum punctulatum
Ulothrix aequalis
Vaucheria geminata Fig.

Red Algae (Rhodophyceae) :
Batrachospermum vagum
Hildenbrandia rivularis
Lemanea annulata

a

~

w
Seep ep a wf

ib

Diatoms (Bacillariophyceae) :
Amphora ovalis
Cocconeis placentula
Cyclotella bodanica
Cymbella cesati
Meridion circulare
Navicula exigua var. capitata
Navicula gracilis
Nitzschia linearis
Pinnularia nobilis
Pinnularia subcapitata
Surirella splendida
Synedra acus var. angustissima

ee  F PL

Flagellates (Chrysophyceae, Cryptophyceae, Euglenophyceae and
Volvocales of Chlorophyceae) :

Chromulina rosanoffi 4
Chroomonas nordstetii
Chroomonas setoniensis
Chrysococcus maior
Chrysococcus ovalis
Chrysococcus rufescens -
Dinobryon stipitatum
Euglena ehrenbergii
Euglena spirogyra
Mallomonas caudata 1
Phacotus lenticularis 4
Phacus longicauda
Rhodomonas lacustris 4

Some workers have emphasized the relationship of whole
groups of algae to pollution in studies involving stream puri-
fication. Lackey (8) reported that two classes of algae, the
olive-green flagellates, or Cryptophyceae, and the yellow-
green flagellates, or Chrysophyceae, appeared to be indi-
cators of clean, unpolluted water. They tended to be present
in moderate to great abundance in clean water and reacted
adversely to pollution. In another study (4) he observed
that all of the Chrysophyceae and most of the Cryptophyceae,
Volvocales, and Bacillarieae (diatoms) which were present
in clean water were killed in the zone of pollution. Patrick
(9) stated that a “healthy” portion of a stream contained
algae which are mostly diatoms and green algae. Rafter (10)
and other earlier workers assumed that the absence of large
amounts of blue-green algae was an indication of clean water.

It is apparent that the lists of clean water algae as reported
by various workers include a wide variety of forms belonging
to various groups. Some are planktonic while others are
epiphytic or attached to rocks and other material on the
bottom of the stream.

REFERENCES

1. The microscopy of drinking water. Ed. 4. G. C. Whipple, G. M.
Fair, and M. C. Whipple. J. Wiley and Sons, N.Y., 586 p.
With 19 color plates. 1948.

2. Pollution and repurification as indicated by the algae. R. W.
Butcher. Fourth International Congress for Microbiology,
held 1947. Rept. of Proc. 1949.

3. Oekologie der Saprobien. Uber die Bezeihungen der Wasseror-
ganismen zur Umwelt. R. Kolkwitz. Schriftenreihe des
Vereins fiir Wasser-, Boden-, und Lufthygiene. No. 4, 64 p.
1950.

4. Stream enrichment and microbiota.
Health Repts. 71: 708-718. 1956.

5. Handbuch der Frischwasser-, und Abwasserbiologie. H. Lieb-
mann. R. Oldenbourg, Miinchen, Germany, 539 p. 1951.

6. Factors effecting the distribution of diatoms. Ruth Patrick.
Bot. Rev. 14: 473-524. 1948.

7. Biological studies, Ohio River pollution survey. I. Biological
zones in a polluted stream. F. G. Brinley. Sewage Wks.
Jour. 14: 147-159. 1942. i

8. Two groups of flagellated algae serving as indicators of clean
water. J.B. Lackey. Jour. Amer. Water Wks. Assn. 33: 1099-
1110. 1941.

9. A proposed biological measure of stream conditions Ruth
Patrick. Proc. 5th Indust. Waste Conf., Purdue Univ. Eng.
Bull. 34: 379-899. 1950.

10. The microscopical examination of potable water.
Van Nostrand Co., N.Y. 1900.

J. B. Lackey. Public

G. W. Rafter.
''CHAPTER VIII

PLANKTON AND OTHER

THE WATER REQUIREMENTS of growing cities and
industry place increasing demands on surface water sup-
plies. Already, the majority of the larger communities are
forced to rely primarily on surface rather than ground
water. More and more attention must therefore be given
to both pollution control and treatment of the water par-
ticularly as supplies from less desirable sources have to be
tapped (1).

Reservoirs, lakes, rivers, and smaller streams are all
normally capable of supporting large mixed groups of
aquatic plants and animals. Algae of many kinds are in-
cluded in this population. In lakes, reservoirs, and large
rivers the common forms would be those found especially at or
near the surface of the water where light is present in suf-
ficient intensity to permit the algae to carry on their es-
sential process of photosynthesis. The planktonic algae are
capable of growing and multiplying while dispersed in the
water and unattached to solid objects (2). Many other
algae may be carried away from the shore line and from
shallow ponds to become mixed with the true planktonic
forms or to collect as mats of growth on the surface. Some
species of algae are able to develop in abundance at depths
of 10, 20, or more feet below the surface.

Recent studies indicate that there are many very minute
algae and related organisms present in the water, and that
these may often exceed in volume the larger microscopic
forms. These very minute forms, are called “nannoplank-
ton,” and the smallest of these are generally missed in the
routine plankton analysis of water, in which only a low
magnification with the compound microscope is used (3).
The possible importance of these very small forms has not
vet been given much consideration.

The larger unattached algae constitute the bulk of the
plankton counts made at many water treatment plants. So
long as the total count remains low and no taste-and-odor
algae nor filter-clogging forms are present in conspicuous
numbers, the waterworks engineer assumes that he is un-
likely to have serious difficulties with the algae. A reason-
able number of various kinds of common plankton organ-
- isms indicates a balanced biological condition in his raw
-water supply, implying that it will respond to water works
treatment with the minimum of trouble. If one group,
such as the blue-greens or the diatoms, or one particular
species, such as Anacystis cyanea (formerly called Micro-
cystis aeruginosa) or Dinobryon divergens, begins to pre-
dominate, then he becomes alert for possible trouble and can
treat. for the control of algae before undesirable conditions
become serious. When blue-green algae become predom-
inant, it frequently indicates either that the water has been

SURFACE WATER ALGAE

enriched with organic matter or that previously there has
been a superabundance of diatoms. An understanding of
relationships of this sort helps in instituting measures to
prevent troublesome growths from developing (4).

In waters poor in nutrients, the factors limiting the number
of algae may be the amounts of food materials available, par-
ticularly nitrates, phosphates, and, for diatoms, silicates.
Some localities are proposing to restrict the algal growths in
the raw water supply by removal of phosphate through caus-
ing it to precipitate as ferric phosphate. In one of the
western cities a problem developed when 20 percent of a
ground water containing approximately 5 to 10 p.p.m. nitro-
gen as nitrate was mixed with a relatively infertile surface
supply, causing heavy growths of the green algae, Golenkinia,
Palmella, and Scenedesmus. In England, the addition of
ground water to a reservoir caused a copious growth of the
yellow-green alga, 77ibonema. The growths of algae in some
localities have been so rank as to necessitate withdrawing the
reservoir from service. Many bodies of water are sufficiently
rich in the essential nutrients that these nutrients do not be-
come limiting factors in determining the abundance of algae.
Other factors such as turbidity, water temperature, and para-
sitism may be the critical ones. Although it is assumed that
the chemical and physical environment largely determines the
amount of algal production, the exact relationships remain
in many respects obscure.

BLOOMS

A number of the surface water algae have the ability to
accumulate, at times, in such numbers as to form loose, visible
aggregations called “blooms,” which may cover very large
areas of lakes and reservoirs or even streams. Blue-green
algae may form these water blooms particularly during
periods of warm, calm weather, when the algae which pre-
viously were distributed through the water rise to the surface.
Other blooms may be associated with a rapid reproduction of
a particular alga. Some water blooms have resulted in fish
kills by interfering with reaearation, by excluding light nec-
essary for photosynthesis in the lower areas and thereby
preventing release of oxygen into the water, or by depleting
the oxygen through decay or respiration within the bloom.
Some water blooms release substances extremely toxic to fish,
domestic animals, and birds, and extensive kills have resulted
in several areas (5).

A considerable number of species of algae are capable of
producing blooms. Some of the genera most frequently in-
volved are the blue-green algae, Anacystis (Microcystis),
Anabaena, Aphanizomenon, and Oscillatoria; the green al-
gae, Hydrodictyon, Chlorella, and Ankistrodesmus (fig. 35) ;

43
''44, ALGAE IN WATER SUPPLIES

 

the diatoms, Synedra and Cyclotella; and the flagellates,
Synura, Euglena, and Chlamydomonas. Blooms of blue-
green algae are particularly obnoxious. Blooms of flagellates
and green algae are often encouraged by the addition of fer-
tilizer in farm hatchery ponds in order to increase fish pro-
duction (6).

 

Figure 35.—Ankistrodesmus falcatus.

Related to the blooms, are the “mats” or “blankets” (fig.
36) of filamentous green algae such as Spirogyra, Zygnema,
Oedogonium, and Cladophora which at times may cover
large areas of a reservoir or lake (7). Certain blue-green
algae, such as Glocotrichia natans (fig. 87) may also form
extensive floating masses. These growths cause an unsightly
appearance in a community’s water supply and serve as
breeding places for gnats and midge flies. They may clog
intake screens, cause tastes and odors, and interfere with

the functioning of multiple purpose reservoirs by collecting
as debris on the shores and interfering with fishing and
bathing. Many of the mat-forming algae are resistant to
effective treatment with copper sulfate. Frequent inspec-
tions of raw water supplies for detection of the visible
growths, together with routine microscopic analyses of wa-
ter samples are necessary if the various kinds of algae are
to be effectively controlled.

The list of surface water algae covered in the manual is
given in table 9. It is more extensive than for the other
groups and includes a total of 68 species with 22 illustrated
in color on plate 5. Many of the species on the other lists
in this manual could also be considered as prominent mem-
bers of the flora of surface waters. Additional species
would also need to be added to make the list fairly repre-
sentative for any particular locality. Since the total num-
ber of known species of algae is several thousand, it is ob-
viously not possible to include here all of even the common
forms. Transeau (8) lists, for example, 275 species of the
genus, Spirogyra; Hustedt (9) describes more than 125
species belonging to the genus, Navicula; and Gojdics (10)
recognizes 155 species of H'uglena.

It is emphasized that not all of the algae in the list of
surface water forms are planktonic. The list includes algae
which may be originally benthic (attached and bottom-
dwelling) forms but are frequently swept away into the
open water.

 

Figure 36.—A surface blanket of filamentous algae.
''Plankton and Other Surface Water Algae 45

 

 

Figure 37.—Gloeotrichia natans.

The open water algae have several mechanisms which aid
in keeping them dispersed in the water and retard any
tendency toward settling out. The pigmented flagellates,
represented on plate 5 by Euglena, Phacus, Goniwm, and
Eudorina, are swimming forms with whip-like flagella
which apparently aid in the forward movement of the cells
through the water. Spines or the spine-like shapes of entire
cells help to keep certain nonswimming green algae, such
as Actinastrum, Micractinium, and Scenedesmus, suspended
in the water. The large flat. surfaces exposed to the water
do the same thing for the diatoms Fragilaria and Tabellaria,
and the green alga, Pediastrum. A number of planktonic
blue-green algae have internal “gas vacuoles” which help to
keep the cells afloat.

Various shapes are found among the surface water algae.
Spherical or sub-spherical colonies of cells are found in
Coelastrum, Oocystis, Gomphosphaeria, and Sphaerocystis.
Filamentous forms include Nodularia, Mougeotia, Zygnema.
Cylindrospermum, Melosira, and Desmidium. The diatoms
Stauroneis and Navicula are boat-shaped and capable of
moving through the water. The odd-colored Botryococcus
with its green cells embedded in a brownish mucilaginous
sheath is often irregular in form and surface.

From their specialties in shape and internal structure,
many of the algae can be recognized readily under the
microscope (fig. 38). This makes possible, in the routine
microscopic analysis of water samples, a record of the pres-
ence and abundance of many of the significant species. Sev-
eral helpful books have been published recently, giving lists,
keys, descriptions, and illustrations of the algal flora of par-
ticular States or regions. Examples of these are the algae of
Illinois (11), algae of Tennessee (12), algae of the western
Great Lakes area (13), and the algae of the United States
(14). Available information of this character will facilitate
the accurate recording of the algae found in streams, lakes,
and reservoirs which are being used as the water supply for
an ever-increasing number of cities, towns, and industrial
establishments.

Each year a seasonal cycle is evident in the plankton pop-
ulation of lakes and reservoirs. Diatoms generally increase
in number in late winter, often with two or three additional
pulses occurring during the spring months. In early sum-
mer, the green algae are likely to be abundant followed in
the late summer and early autumn by an increased growth
of blue-greens. Then there will follow a late autumn max-
imum of diatoms. Throughout most of the winter the di-
atoms and certain other algae may remain in the water but
with little or no increase in numbers until conditions, in the
late winter, stimulate the organisms to begin the cycle all

 

 

Figure 38.—Plankton diatoms, showing distinctive shapes of cells and
colonies. The relative sizes of the various organisms are also evident
in this composite photomicrograph which was furnished by J. R.
Baylis, Engineer of Water Purification, Department of Water and
Sewers, Bureau of Water, Chicago, Ill.

over again. Various brown and green flagellates and the
yellow-green alga 7Z'ribonema occasionally appear in the
cycle as abundant growth for brief periods, the time of year
depending in part upon the particular species involved.

When records are kept for a long period of time of the
phytoplankton present in a reservoir or lake, they often re-
veal that certain genera and species are predominant year
after year. In one metropolitan district (15) the reservoirs
contained enormous numbers of 7'abellaria and Ceratium
with an abundance also of Asterionella, Fragilaria, Synedra,
Oyclotella, Dinobryon, and Pandorina. Over a period of ap-
proximately 40 years, however, there was a gradual change
in the predominant algae. Z'adellaria dropped out com-
pletely and new forms appeared, chiefly Stephanodiscus
astraea and Stephanodiscus hanteschii, together with sev-
eral filamentous blue-green algae.
''46 ALGAE IN WATER SUPPLIES

 

Table 9.—Plankton and Other Surface Water Algae

Group and algae

Blue-Green Algae (Myxophyceae) :
Anacystis thermalis
Cylindrospermum stagnale 5
Gloeotrichia natans Fig. 37
Gomphosphaeria aponina 5
Gomphosphaeria lacustris, collinsii type
Gomphosphaeria wichurae
Lyngbya versicolor
Nodularia spumigena 5
Nostoc carneum
Oscillatoria agardhii
Phormidium retzii
Plectonema tomasiniana
Scytonema tolypothricoides
Spirulina nordstedtii

Filamentous Green Algae
phyceae):

Cladophora fracta
Desmidium grevillei 5
Hyalotheca mucosa
Mougeotia genuflexa
Mougeotia scalaris OD
Oedogonium idioandrosporum
Spirogyra fluviatilis
Spirogyra varians
Stigeocolonium stagnatile
Tribonema minus
Ulothrix tenerrima
Vaucheria terrestris
Zygnema pectinatum
Zygnema sterile 5

(of Chlorophyceae and Chryso-

Nonfilamentous, Non-Motile Green Algae (of Chlorophyceae) :
Actinastrum gracillimum
Actinastrum hantzschii
Ankistrodesmus falcatus
Botryococcus braunii
Chlorella ellipsoidea
Closterium aciculare
Coelastrum microporum 5
Cosmarium botrytis
Crucigenia quadrata
Dimorphococcus lunatus

Fig. 34
5

Euastrum oblongum 5
Kirchneriella lunaris

Micractinium pusillum 5
Oocystis borgei 5
Ophiocytium capitatum

Pediastrum boryanum 5

Pediastrum duplex
Scenedesmus bijuga
Scenedesmus dimorphus
Scenedesmus quadricauda 5
Schroederia setigera

Selenastrum gracile

Sphaerocystis schroeteri 5
Staurastrum polymorphum

Fig. 38

Diatoms (Bacillariophyceae) :
Cyclotella glomerata
Cymatopleura solea
Fragilaria capucina 5
Gyrosigma attenuatum
Melosira crenulata
Navicula radiosa
Rhizosolenia gracillis
Rhopalodia gibba
Stauroneis phoenicenteron 5
Stephanodiscus hantzschii 5
Synedra capitata

Plate or Figure

Group and algae Plate
Flagellates (Chrysophyceae, Euglenophyceae, and Volvocales of
Chlorophyceae) :

Dinobryon sociale

Eudorina elegans 5
Euglena gracilis 5
Gonium pectorale 5
Phacus pleuronectes 5

Although many environmental factors are relatively con-

stant for any body of water and tend to keep the phyto-
plankton population stable, other factors will change suf-
ficiently to influence the growth and relative abundance of
the various genera and species comprising the flora.

OO

10.

Ea

13.

. A new counting slide for nannoplankton.

. The importance of algae to waterworks engineers.

. Toxic fresh-water algae. W.

. The population of the blanket-algae of fresh-water pools.

. The fresh-water algae of the United States.

REFERENCES

. Ecology of significant organisms in surface water supplies.

C. M. Tarzwell and C, M. Palmer. Jour. Amer. Water Wks.

Assn. 43: 568-578. 1951.

. Some relationships of phytoplankton to limnology and aquatic

biology. G. W. Prescott. P. 65-78 in Problems of lake biology,
by F. R. Moulton. Amer. Assn. for Advancement of Sci., Science
Press, Lancaster, Pa. 1939.

C. M. Palmer and
T. E. Maloney. Amer. Soc. Limnol. and Oceanog., Special
Publ. No. 21, 6 p. March 1954.

Ja We Gs
Lund. Jour. Inst. Water Engrs. 8: 497-504. 1954.

M. Ingram and G. W. Prescott.

Amer. Midland Naturalist 52: 75-87. 1954.

. Manganese for increased production of water-bloom algae in
ponds. C. Henderson. Progressive Fish-Culturist 11: 157-159.
1949.

Emilie

L. Platt. Amer. Naturalist 49: 752-762. 1915.

. The Zygnemataceae (fresh-water conjugate algae) with keys for

the identification of genera and species. E. N. Transeéau.
Ohio State Univ. Press, Columbus, Ohio, 327 p. 1951.

. Bacillariophyta (Diatomeae). F. Hustedt. Heft 10 in Die
Siisswasser-Flora Mitteleuropas, by A. Pascher. Gustav
Fisher, Jena, Germany, 466 p. 1930.

The genus Euglena. Mary Gojdics. Univ. Wisconsin Press,

Madison, Wis., 268 p. 1953.
The algae of Illinois. L. H. Tiffany and M. E. Britton.
Chicago Press, Chicago, Ill., 407 p. 1952.

Univ.

- Handbook of algae with special reference to Tennessee and the

southeastern United States. H. S. Forest. Univ. Tennessee
Press, Knoxville, Tenn., 467 p. 1954.

Algae of the western Great Lakes area, exclusive of desmids and
diatoms. G. W. Prescott. Cranbrook Inst. Sci., Bloomfield
Hills, Mich., Bull. No. 31, 946 p. 1951.

Ed. 2. G. M. Smith.

McGraw Hill, N.Y., 719 p. 1950.

. The reservoirs of the Metropolitan Water Board and their in-
fluence upon the character of the stored water. E. W. Taylor.
Proc. International Assn. Theoretical and Appl. Limnol.
12: 48-65. 1955.
''CHAPTER IX

ALGAE ATTACHED TO RESERVOIR WALLS

MANY of the algae which grow attached to some substrate
are large and conspicuous, often covering a considerable area
and extending several inches into the water. Those of im-
portance in water supplies may grow not only in the stream,
lake, and reservoir, but in the treatment plant itself. These
algae are commonly found attached to such objects as the
wet concrete walls of settling basins, the screens at the ends
of the intake pipes, and the wood, brick, stone riprap, or even
soil surfaces of reservoir walls and bottoms. Many are
abundant in streams where they may be attached to sub-
merged twigs or rock and other materials forming the
stream bed.

In small amounts these algae are not a cause for alarm,
but when abundant they may become a decided nuisance.
They may clog screens to which they are attached, and re-
duce the flow in canals by the amount of space they occupy
and the increased friction of their surfaces. In multiple-
purpose lakes and reservoirs, they often interfere with
swimming and fishing or develop such rank growths in the
shallow margins that they are the cause of constant com-
plaints from nearby residents. In addition, they may break
away from their attachments to form unsightly surface mats,
clog screens and filters, or produce offensive odors in the air
and water. Other smaller algal forms may produce a con-
tinuous slimy and slippery. layer on concrete or other sur-
faces, which in swimming pools is undesirable or even
dangerous.

The attached algae considered here number 42 species,
listed under their respective groups in table 10; 21 are illus-
trated in color on plate 6. Included are diatoms, blue-green,
green, and fresh-water red algae, but no flagellates. Many
of these algae grow in the form of unbranched or branched
filaments or tubes and are fastened at one end to the substrate
by means of a special anchoring device. Vaucheria is a
branched, tubular form with several common species (figs.
39, 40). Typical branching filamentous green algae are

     
 
 
    

Ss
<<
of
S
SSoSe

=
S

°

of

=
°

So,

ose

0.
09
0

Figure 39.—Vaucheria
geminata.

Cladophora, Pithophora (fig. 41), Chaetophora, Stigeo-
clonium, Draparnaldia, Bulbochaete, Chara, and Nitella.
The species Cladophora glomerata is a very common attached
alga in rapidly flowing water and is considered the most
abundant filamentous alga in streams throughout the world
(1). Nonbranching filamentous green algae include Oedo-
gonium, Microspora, and Ulothria and the more complex
Schizomeris (fig. 42). The genera, Audouinella (formerly
called Chantransia), Batrachospermum, and Compsopogon
are fresh-water red algae, the last one being common in the
Southern States. Some filamentous blue-green algae such
as Phormidium, Lyngbya, Tolypothria, and Stigonema. (fig.
43) form dense mats, one side of which is exposed and the
other side attached to the substrate.

Some diatoms, such as Achnanthes, Gomphonema, and
Cymbella are attached to surfaces by gelatinous stalks or
tubes. In Australia, Gomphonema developed as an ex-
tensive growth and formed a slippery, felt-like mat covering
the cement walls of an aqueduct for several miles (2). The
species of Cymbella which grows inside a hollow tube, as
illustrated on plate 6, has sometimes been placed in a separate
genus, E’ncyonema (3).

   

   

SSESI° oo 0 1 EG EAP RI FR BE
FES 08 PP? 0029 %

a
SSexe0
SB ES oak

          

Figure 40.—Vaucheria
sessilis.

A white marble surface serving as the floor of an observa-
tion well in one water treatment plant became overgrown
with a continuous brown layer of Achnanthes. The obser-
vation well was located on a conduit carrying water from
sand filters to the clear well. The marble surface was
brushed clean but the color returned again within 2 weeks.
After a second cleaning, electric lights that had been left on
continuously at the bottom of the observation well were then
turned off excepting for brief times when needed for display.
The brown color did not return because the diatoms were not
capable of developing in darkness.

The green alga, Phytoconis (formerly called Protococcus)
is common as a thin green layer on the surface of moist wood
and bark above the water line, but it is seldom found sub-
merged. Another green alga, Z'etraspora (fig. 44), is com-
posed of minute rounded cells in a soft, fragile, mucilaginous,

AT
''48 ALGAE IN WATER SUPPLIES

 

common tube which is attached at one end to the substrate.
It is one of the first algae to develop in abundance in the
cold water of streams and pools after the ice melts in early
spring.

In reservoirs and lakes having rocky rather than sandy
shores, Cladophora and other large filamentous algae often
develop during the summer as extensive massive growths.
When this material becomes detached by wave action and is
thrown up on the shore, it may require immediate removal
to prevent the development of septic odors (4).

Drastic measures often have to be taken to control the
attached algae, especially if the growths are neglected until
large quantities threaten to cause trouble. One city adapted
a floor-cleaning machine, fitted with a cylindrical wire
brush, for use in scraping the algal growth from the con-
crete floor of a 13 million gallon reservoir. The machine
proved to be much more effective than hand scrapers in re-
moving the attached portions of the algae from the more than
100,000 square feet of concrete. The detached algae were
then flushed from the reservoir floor by streams of water
from a fire hose (5). The use of chemicals to kill attached
algae when they are present in quantity may not solve the

Table 10.—Algae Attached to Reservoir Walls

Group and algae
Blue-Green Algae (Myxophyceae):
Calothrix braunii
Lyngbya lagerheimii 6
Lyngbya ocracea
Nostoc pruniforme

Plate or Figure

Oscillatoria tenuis Fig. 30

Phormidium retzii :
Phormidium uncinatum 6

Stigonema minutum

Tolypothrix tenuis 6

Green Algae (Nonmotile Chlorophyceae, Charophyceae):
Bulbochaete insignis 6
Chaetophora attenuata
Chaetophora elegans 6
Chara globularis 6
Cladophora crispata 6
Cladophora glomerata 4
Draparnaldia glomerata 6
Gloeocystis gigas
Microspora amoena 6

Nitella flexilis

Oedogonium boscii

Oedogonium grande

Oedogonium suecicum 6

Palmella mucosa 2

Phytoconis botryoides 6

Pithophora oedogonia Fig. 41
Rhizoclonium hieroglyphicum

Schizomeris leibleinii Fig. 42
Stigeoclonium lubricum

Tetraspora gelatinosa 6
Ulothrix zonata 6
Vaucheria geminata Fig. 39
Vaucheria sessilis 6

Red Algae (Rhodophyceae):
Audouinella violacea 6
Batrachospermum moniliforme 6
Compsopogon coeruleus 6

Diatoms (Bacillariophyceae):

Achnanthes microcephala 6
Cocconeis pediculus

Cymbella prostrata 6
Epithemia turgida

Gomphonema geminatum 6

Gomphonema olivaceum
Rhoicosphenia curvata

 

Figure 42.—Schizo-
meris leibleinii.

Figure 41.—Pithophora
oedogonia.

Figure 43.—Stigonema
hormoides.

 

 

Portion of colony showing cells grouped
Pseudocilia are barely visible on a few of the cells.

Figure 44.—Tetraspora.
in fours.
''Algae Attached to Reservoir Walls 49

 

problem because dead algae as well as living ones can clog
filters and screens, release slimes into the water, and cause
tastes and odors.

In areas in the western part of the country where there
are extensive systems of canals for irrigation farming, mass-
ive growths of attached algae, together with certain aquatic
flowering plants, constitute a serious problem. Because of
their bulk, they impede the flow of water through the ditches
and clog the control gates and the distribution lines. Clad-
ophora and Rhizoclonium are by far the most important
algae encountered. The peak of their development is gen-
erally in the spring after which they often become incon-
spicuous during the summer, with new growth beginning in
the autumn. The green alga Hnteromorpha, commonly
thought of as a brackish water form, may become abundant
during the summer, and the fresh-water red alga, Comp-
sopogon, may flourish during the autumn. One common
method of control has been the mechanical removal of the
algae by means of chains or scrapers that are pulled along
the canals by tractors. Four irrigation districts in Arizona
spend a total of approximately $250,000 annually to control
this growth (6).

Attached algae are present and apparently significant in
the trickling filters of sewage treatment plants. They form
a large part of the population of microorganisms growing
in a layer around the stones of the filter. The exposed sur-
face of the layer is predominantly fungal, the intermediate
portion is predominantly algal, and the basal portion,
against: the stone, is a fungal, algal, and bacterial mixture.
The layer may reach a thickness of 1to2mm. The attached
alga most frequently encountered is Stigeoclonium. In ad-
dition to its branching filaments it also develops as a basal,
attached, irregular tight mat of cells which strongly re-
sembles a colony of the nonfilamentous green alga Chloro-

coccum. The branching filaments of Stigeoclonium rise
from this basal mat. Species of attached algae from the
trickling filters of one treatment plant (7) were reported as
Stigeoclonium nanum, Ulothrix tenuissima, Phormidium
uncinatum, Amphithria janthina and Characium sp. Other
algae commonly mixed with the attached forms were Scene-
desmus bijuga, Oocystis parva, Chlorella vulgaris, Chlamy-
domonas, Niteschia palea and Anacystis montana.

Consideration is being given to the use of attached algae
in tertiary treatment of sewage effluents. In addition the
algal growth might be harvested and prepared for use as
fertilizer, mulch, cattle feed, etc. The attached forms would
not present the difficulty of harvesting that is encountered
with plankton organisms.

Thus it is evident that the attached algae may produce
undesirable conditions or be put to good use depending upon
the particular locations and conditions in which they develop.

REFERENCES

1. The ecology of river algae. J. L. Blum. Bot. Rev. 22: 291-341.
1956.

2. The effects of algae in water supplies. D. H. Matheson. Inter-
national Water Supply Assn., General Rept. to 2d Congress.
Paris, France. 82 p. 1952.

3. Fresh-water biology. H. B. Ward and G. C. Whipple.
and Sons, N.Y., 1110p. 1945.

4. Algal nuisances in surface waters. N. J. Howard and A. E. Berry.
Canadian Jour. Public Health 24: 377-384. 1933.

5. Rout reservoir algae. O. G. Kuran and H. H. Angell. Amer. City
68 (No. 10) : 90-91. Oct. 1953.

6. The study of the algae of irrigation waters. Janet D. Wien.
Arizona State College, Tempe, Arizona. 37. p. (Mimeographed).
Mar. 31, 1958.

7. Continuous sampling of trickling filter populations. II. Popula-
tions. W. B. Cooke and A. Hirsch. Sewage and Indust. Wastes
30: 188-156. 1958.

J. Wiley
''CHAPTER X

ADDITIONAL PROBLEMS CAUSED BY ALGAE

IN WATER

THE WIDESPREAD distribution of algae in water sup-
plies, together with their unique combination of character-
istics, allows them to exert effects in many places and in
many ways. In addition to those activities discussed in the
preceding six chapters, the algae have been implicated in
production of slime in industrial water supplies, causing
coloration of water, inducing corrosion of concrete and of
metals, reducing the potability of treated water by their
presence in distribution systems, interfering with the chemi-
cal treatment of water, and causing illness in man and
animals (1).

SLIME

Slime formation in water can be caused or aided by
various kinds of algae, bacteria, and other organisms (2).
Slime-producing algae are important in open reservoirs and
in uncovered holding basins of recirculating systems. They
can become a serious problem especially in the water. sup-
plies for pulp mills and food industries by causing slime
spots or masses in the products. Coatings of slime may also
develop on condenser tubes in industrial cooling systems and
have the effect of reducing the rate of heat transfer to the
water (3). Slime accumulation in the unlighted portions of
distribution systems may be due to bacteria, to the tardy
settling out of the coagulant, or to other agents, but not to
algae.

Algal slime commonly is derived from the mucilaginous
capsule or sheath which envelops the cells. The blue-green
algae as a group are notorious slime producers. Their tech-
nical name, Myxophyceae, contains the prefix “myxo” which
means slime or mucus. Several diatoms as well as green and
red algae and a few flagellates also produce slimy sheaths
or capsules. A few of the slime-forming algae are given in
table 11.

COLORATION

Algal coloration of finished water is most frequent in com-
munities that have uncovered storage reservoirs in the dis-
tribution system, or where the treatment of the raw water
supply is not efficient in reducing the numbers of phy-
toplankton present. Almost any small alga capable of rapid
multiplication could be involved. Complaints come from
patrons when the water from the faucet is colored, or when

50

SUPPLIES

a colored marginal ring forms at the surface of the water
in the tumbler or bathtub. Colors ranging from yellow-
green through green, blue-green, red, and brown to black
could all be due to algae. In table 11 are listed some of the
algae that have been implicated. However, colors in water
may also be caused by substances other than algae.

CORROSION

Corrosion of concrete and of metals in pipes and boilers is
a continual problem. Algae sometimes contribute to cor-
rosion either directly in localized places where they may be
growing or through their modification of the water by physi-
cal or chemical changes. Green and blue-green algae, along
with lichens and mosses growing on the surface of sub-
merged concrete, have caused the concrete to become pitted
and friable. The effect was most pronounced when the per-
centage of SO; in the mortar was 0.6 or higher. Some of
the algae associated with this change are given in table 11.
It is assumed that the gelatin present in the living plants
together with the carbonic, oxalic, and silicic acids produced
by them are adequate to corrode the cement (4).

Typical algae are unlikely to be the direct cause of corro-
sion of iron or steel pipes in a distribution system because
most are incapable of active growth in the absence of light.
However, algae have been reported to cause corrosion in
metal tanks or basins open to sunlight. Oscillatoria grow-
ing in abundance in water in an open steel tank has caused
serious pitting of the metal. The pits were bright and clean
because the iron was apparently going into solution and not
producing any covering compound such as an oxide or sul-
fide. The algal growth permitted the pitting to take place
by releasing oxygen which combined with the protecting
film of oxide over the steel. When the steel tank was cov-
ered to prevent entrance of light, the algae disappeared and
the corrosion stopped (5).

Indirectly, algae may affect the rate of corrosion in a
number of ways. Increase in organic deposits in the pipe,
increase in the dissolved oxygen in the water through photo-
synthesis in the raw water supply, and changes in the pH,
CO, content, and calcium carbonate content of the water can
all be brought about by algae. These changes can, in turn,
affect the rate of corrosion. Iron and sulfur bacteria may
have a more direct relationship to corrosion and may be sig-
nificant particularly on the outside surfaces of pipe buried
in the ground.
''Additional Problems Caused by Algae in Water Supplies 51

 

ALGAE IN TREATED WATERS

The persistence of algae in the water of distribution sys-
tems tends to become more pronounced as additional surface
water supplies are tapped, but less evident as effective meas-
ures for reducing the plankton in the water are practiced.
As most algae cannot grow and multiply without light, the
only algae which would be encountered in the pipes of the
distribution system would be first those not removed in the
treatment process; second, the few algae unusual in their
ability to grow in the dark; and third, those that develop
in an uncovered reservoir containing treated water. The
algae capable of growth in the dark include some species
of Scenedesmus, Euglena, Anacystis,
Chlorococcum.

Since the treated water in most distribution systems has
a free chlorine residual, the algae most likely to remain intact
in the pipelines would be the chlorine-resistant forms. These

algae might be capable of carrying into the distribution sys-
tem living bacteria, presumably even pathogenic forms,
which are protected from the lethal effect of the chlorine
by being embedded in the gelatinous covering surrounding
the algal cells (6). Algae reported to be resistant to chlorine
in distribution systems include Hlaktothrix gelatinosa,
Gomphosphaeria aponina, Closteriwm (fig. 45), Cosmarium,

2

Coelastrum, and

and Chlorella.

a

ak

Table 11.—Additional Problems Caused by Algae in Water Supplies

Problem and algae
Slime-producing Algae:

Algal group

Anacystis (Aphanocapsa, Gloeocapsa) Blue-green
Batrachospermum Red
Chaetophora Green
Cymbella Diatom
Huglena sanguinea var. furcata Flagellate
Euglena velata Flagellate
Gloeotrichia Blue-green
Gomphonema Diatom
Oscillatoria Blue-green
Palmella Green
Phormidium Blue-green
Spirogyra Green
Tetraspora Green
Algae Causing Coloration of Water:
Color of water
Anacystis Blue-green Blue-green
Ceratium Rusty brown Flagellate
Chlamydomonas Green Flagellate
Chlorella Green Green
Cosmarium Green Green
Euglena orientalis Red Flagellate
Euglena rubra Red Flagellate
Euglena sanguinea Red Flagellate
Oscillatoria prolifica Purple Blue-green
Oscillatoria rubescens Red Blue-green
Algae Causing Corrosion of Concrete:
Anacystis (Chroococcus) Blue-green
Chaetophora Green
Diatoma Diatom
Euglena Flagellate
Phormidium Blue-green
Phytoconis (Protococcus) Green
Algae Causing Corrosion of Steel:
Oscillatoria Blue-green
Algae Persistent in Distribution Systems:
Anacystis Blue-green
Asterionella Diatom
Chlorella Green
Chlorococcum Green
Closterium Green
Coelastrum Green
Cosmarium Green
Cyclotella Diatom
Dinobryon Flagellate
Elaktothrix gelatinosa Green
Epithemia Diatom
Euglena Flagellate
Gomphosphaeria aponina Blue-green
Scenedesmus Green
Synedra Diatom

Problem and algae

Algae Interfering With Coagulation:

Oodinium ocellatum

Algal group

Anabaena Blue-green
Asterionella Diatom
Euglena Flagellate
Gomphosphaeria Blue-green
Synedra Diatom
Algae Causing Natural Softening of Water:
Anabaena Blue-green
Aphanizomenon Blue-green
Cosmarium Green
Scenedesmus Green
Synedra Diatom
Toxic Marine Algae:
Caulerpa serrulata Green
Egregia laevigata Brown
Gelidium cartilagineum var. robustum Red
Gonyaulax catenella : Dinoflagellate
Gonyaulax polyedra Dinoflagellate
Gonyaulax tamarensis Dinoflagellate
Gymnodinium brevis Dinoflagellate
Gymnodinium. veneficum Dinoflagellate
Hesperophycus harveyanus Brown
Hornellia marina Flagellate
Lyngbya aestuarii Blue-green
Lyngbya majuscula Blue-green
Macrocystis pyrifera Brown
Pelvetia fastigiata Brown
Prymnesium parvum Flagellate
Pyrodinium phoneus Dinoflagellate
Trichodesmium erythraeum Blue-green
Toxic Fresh-water Algae:
Anabaena Blue-green
Anabaena circinalis Blue-green
Anabaena flos-aquae Blue-green
Anabaena lemmermanni Blue-green
Anacystis (Microcystis) Blue-green
Anacystis cyanea (Microcystis aeruginosa ) Blue-green
Anacystis cyanea (Microcystis flos-aquae ) Blue-green
Anacystis cyanea (Microcystis toxica) Blue-green
Aphanizomenon flos-aquae Blue-green
Gloeotrichia echinulata Blue-green
Gomphosphaeria lacustris (Coelosphaerium Blue-green
kuetzingianum )
Lyngbya contorta Blue-green
Nodularia spumigena Blue-green
Parasitic Aquatic Algae:
‘ ‘ i Dinoflagellate
Oodinium limneticum Diacdagelinie

Figure 45.—Closterium
lunula, a desmid.

In one water supply receiving a normal
chlorine treatment but no coagulation or filtration, counts
of up to 2,200 algae per ml. were recorded for the tap water.
''52 ALGAE IN WATER SUPPLIES

 

In the counting, no distinction was made between living and
dead organisms. Some of the most abundant genera were
Asterionella, Cyclotella, Dinobryon, and Synedra (7).

Reservoirs in the distribution system can be provided with
covers to keep out the sunlight and thus prevent the growth
of algae. Ground waters stored in open reservoirs are often
more susceptible to prolific algal growths than are treated
surface waters, possibly because their lower turbidity per-
mits greater light penetration. The ground waters usually
contain in solution a supply of nitrates, phosphates, iron,
silica, and carbonic acid in quantities sufficient to support
the phytoplankton and especially the diatoms. The ground
water is easily seeded with algae and other organisms which
may be carried to the reservoir by the wind or on the bodies
of aquatic birds. The algae can impart their characteristic
odors to the stored water and these can be carried into the
remainder of the distribution system (8).

Algae that persist in distribution systems can increase the
organic content of the water sufficiently to deplete the
residual chlorine in the water. In addition, this organic
content may feed bacteria, blood worms, nematodes, cope-
pods, fresh-water sponges, bryozoa, and other undesirable
organisms. Organisms that grow attached to the inner sur-
face of the pipes are commonly known as “pipe moss.”

ROLE OF ALGAE IN WATER TREATMENT PROBLEMS

Interference by algae with the chemical treatment of
water can be due to the changes they cause in pH, alkalinity,
total hardness, and dissolved oxygen (D.O.) of the raw
water, or to their increasing of the organic content carried by
the water. It may be necessary, for example, to vary the dos-
age of chlorine in direct proportion to the quantity of algae
present in order to obtain a constant amount of residual
chlorine in the water.

In the clarification of water it is necessary to treat water
with a coagulant aid in addition to the coagulant if the raw
water has a low plankton population and low turbidity due
to silt or other particles. The aid may be finely divided
clay, bentonite, fuller’s earth, activated carbon, or similar
materials composed of finely divided insoluble particles.
The addition of a small amount of the aid will furnish
particles which act as centers for the formation of the floc.
Asterionella and Synedra have been reported as inhibiting
proper floc formation (9). While it is possible that these
particular kinds of algae might give more difficulty than
others during coagulation and sedimentation, the total vol-
ume of all the algae is apparently more important. Sedi-
mentation alone would permit dead algae to settle out grad-
ually along with clay and other inorganic particles present.
The living planktonic algae would tend to remain distrib-
uted throughout the water in the absence of a coagulant.

Many industrial establishments require a water with nar-
row ranges of variation in physical and chemical character-
istics. In one Connecticut city (10) the felting and dyeing
processes are a part of the major industries, and they re-

quire a water free of color, turbidity, iron and aluminum
and with low and constant pH and hardness. The city
water treatment plant is charged with the responsibility of
supplying water satisfactory for the city’s industries. The
raw water supply comes from reservoirs which support
populations of algae that change in concentration from day
to day. As this change occurs, small daily adjustments in
chemical feed, equipment and operational methods are made
in the water treatment plant in order to maintain the pre-
determined optimum conditions such as turbidity of not
more than 2.0 on the filters, minimum filter runs of 23 hours,
maximum pH of 6.7 in the treated water, minimum rates of
flow of 70,000 gallons per foot head loss per filter, and
minimum floc size in the last flocculator of 2.0 mm. é

Normally a large floc particle is obtained quickly and
without agitation. Agitators are used, however, when
certain free floating algae, particularly Gomphosphaeria
and Anabaena, are abundant. The agitation causes smaller
floc particles to be formed which in this situation gives a
settled water with lower turbidity and color than would be
obtained with large floc particles.

Daily blooming of algae in the reservoirs frequently in-
duces the formation of a weak floc during coagulation in the
treatment plant and allows appreciable amounts of undesired
substances to remain in the water and to pass through the
sand filters into the finished water. The blooming of the
algae may cause the pH of the raw water to rise from 7.0 to
10.0 in a few hours. It is the high pH which causes a poor
floc to be formed when alum is added. Formerly the im-
portance of algae in causing this change was not recognized,
and treatment plant operators were continually puzzled by
the sudden inexplicable shift to a settled water of poor
quality. During the high peak of the pH cycle the normal
amount of alum which they had added to the water was in-
sufficient to lower the pH to the point where good floc
formation would occur.

In some cases, the pH of the finished water is adjusted to
be within a desired range for industry by the addition of
acid or alkali. The water for a certain steel mill requires
approximately 800 pounds of 60 percent H,SO, per day to
keep the pH of the water down to 8 as it is drawn from a
320-acre lake. The algae in this lake are responsible for
increases in the pH of the water, and regular phytoplankton
counts are made as an aid in estimating the amount of
change in pH which will occur.

In another state a reservoir of 350 acres had a total hard-
ness normally of 120 p.p.m. In early June of one year this
suddenly dropped to 90 p.p.m. The D.O. increased from
8.3 to 13.0 p.p.m.; the pH, from 8.6 to 8.9; the carbonate
alkalinity from 20 to 30 p.p.m; and the turbidity from 9 to
18 p.p.m. At the same time the blue-green alga, Anabaena,
which was then the dominant form, increased from 750 to
4,730 areal standard units per ml. Favorable conditions
were created for the precipitation of calcium carbonate and
thus a softening of the water. According to the report, the
many cells of Anabaena had utilized sufficient “half-bound”
carbon dioxide in their metabolism to increase the pH, which
''Additional Problems Caused by Algae in Water Supplies 53

 

in turn made possible the precipitation of the calcium car-
bonate (11). Other algae have been observed to bring about
a similar change. These are listed in table 11. British ex-
perience has shown that vigorous algal growths of many
kinds can reduce water hardness by as much as one-third
(12).

TOXICITY OF ALGAE

Illness in man and animals has been attributed to both
marine and fresh-water algae. A toxic agent produced by
the marine armored flagellate Gonyaulax (18) can cause
serious illness in man following eating of clams that have
fed on particular species of this genus. The poison has been
described as a toxin 10 times as potent for mice as strychnine.
Gonyaulax and Gymnodinium, another armored flagellate
may accumulate in very large numbers in ocean water near
the shore and produce a condition known as “red tide,” “red
water,” or “yellow-green peril.” These flagellate blooms
have been reported for a number of localities throughout
the world, including the coasts of California, Florida, and
Texas, as well as Peru, Japan, Australia, India, Africa and
Europe. Shellfish poisoning due to Gonyaulax has also been
reported for Quebec, Nova Scotia, New Brunswick, and Van-
couver Island in Canada, and for California, Alaska, Ore-
gon, Maine, Mexico, British Isles, Norway, France, Belgium,
and New Zealand (14, 15).

Many kinds of fish and other marine animals are often
killed during the time of the red tide but perhaps as the
result of other factors than the toxin since according to some
workers the poison has little or no effect on fish. When the
decaying fish are washed up on the beaches, the stench and
the need for quick disposal constitute a serious problem for
the communities affected. Gymnodinium veneficum, a
species related to red tide algae, has been found to kill fish
in a short time and is lethal also to shell fish, arthropods
and echinoderms (16).

Several other marine algae have been implicated as caus-
ing reef fishes to be poisonous in some areas. Large numbers
of poisonous fishes are known to be herbivorous, and con-
siderable evidence exists to indicate that these fish are
poisonous as food only after they have fed on certain kinds
of algae (17). In a large majority of the poisonous fishes
that were examined, the blue-green alga Lyngbya (fig. 46)
was detected in the alimentary tract. Lyngbya majuscula
and Lyngbya aestuarté were the common species in the area
and in the fish samples. It is interesting to find a report
published in 1904 that “numbers of horses have frequently
been killed by feeding on Lyngbya majuscula which occurs
in abundance on the coral beaches in the Gulf of Manor”
along the coast of India (18). Other marine algae have
been found toxic to mice, but their possible toxicity to man
has not been determined (19). An algal flagellate, Prym-
nesium parvum, reported for Europe and common in brack-
ish water ponds in Israel, produces an extracellular toxin
which has resulted in mass mortality among fishes and in
Israel is considered the most serious natural obtacle to fish
breeding (20).

Toxic fresh-water algae affecting man have been reported
in the United States and elsewhere. Contact type dermatitis
and symptoms of “hay fever” have been reported to be
caused by blue-green algae. Anabaena was implicated in
the former reaction (21) while Anacystis (Microcystis) and
Lyngbya contorta were listed for the latter (22). In a few
cases the green alga Chlorella has been found associated with
fungi in mycotic lesions in man, but its significance has not
been determined (23). Unexplained outbreaks of gastroen-
teritis involving thousands of people, and possibly related
to the water supplies, have been reported in the same areas
where extensive algal blooms were present (24). However,
any direct relationship between the algal blooms and the
intestinal disorders in humans has not been clearly demon-
strated (25). It has been suggested as a possibility that
the disintegration of large amounts of blue-green algae on
the sand filters of water treatment plants and the passage
of toxic products into the distribution mains may be the
cause of the gastro-intestinal disturbances (26).

There are many records of acute and often fatal poison-
ing of livestock where the animals had been drinking from
ponds containing dense algal blooms (27). Animals affected
have included horses, cattle, hogs, sheep, dogs, rabbits, and
poultry. In all cases the algae implicated as the toxic agents
are blue-greens, Anacystis (Microcystis) being the genus
most often involved. The first alga reported as toxic was
Nodularia spumigena (fig. 47). The several genera and
species which are reported as toxic are listed in table 11.
Areas which have reported poisoning of animals, presum-
ably due to algal blooms, include Colorado, Idaho, Iowa,
Michigan, Minnesota, Montana, North Dakota, South Da-
kota, Wisconsin, and Alberta, Ontario, Bermuda, Argentina,

 

Figure 46.—Lyngbya majuscula, showing empty sheath extending

between threads of cells.
''54 ALGAE IN WATER SUPPLIES

 

Finland, Australia, and South Africa (28). The outbreaks
have occurred only during the summer months when algae
are abundant. The symptoms associated with poisoning by
the blue-green algae are generally prostration and convul-
sions followed by death.

Figure 47.—Nodularia spumi-
gena, the first blue-green alga
reported as toxic.

 

A few aquatic algae are known to infect the gills of fish,
causing a disease which interferes with respiration and is
often fatal (29). The dinoflagellate Oodinium ocellatum
parasitizes smal] fresh-water fishes. Other species of this
genus occur in the marine tunicates, annelid worms, and
other aquatic invertebrates (30).

Fish kills in fresh-water lakes and reservoirs have often
been blamed, with considerable justification, on the algae.
When there is a heavy algal growth, a reduction in the
amount of sunlight due to weather conditions will reduce
the photosynthetic activity of the algae. With insufficient
byproduct oxygen being produced the algae are forced to
use in respiration the oxygen stored in the water. If this
condition should exist for any length of time, the water
would lose most of its oxygen causing the algae and in addi-
tion the fish to die of oxygen starvation.

On the other hand, normal amounts of sunshine on a very
thick mat of algae can bring about a fish kill. If the mat
becomes thick enough to prevent the passage of light to
planktonic algae below the surface, the latter will then use
up more oxygen than is produced and oxygen depletion
takes place which, in turn affects the fish.

A balance tends to exist between the amount of algae, the
sunlight, and the total oxygen requirements of the fish and
other aquatic organisms. A rise in water temperature might
easily be the factor which stimulates an excessive growth of
algae and thereby sets off the chain of events leading up to
oxygen starvation and a fish kill (81).

REFERENCES

1. The effects of algae in water supplies.
national Water Supply Assn.
Paris, France. 82 p. 1952.

2. Microscopie organisms in water conduits. G. C. Whipple, G. M.
Fair, and M. C. Whipple. Chapt. 5 in their The microscopy
of drinking water. Ed. 4. J. Wiley and Sons, N.Y. 1948.

3. Experiences in chlorinating condenser circulating water. V. M.
Frost and W. F. Rippe. Wallace and Tiernan Tech. Publ. No.
112, 32 p. 1929.

4. Biological corrosion of concrete. E. T, Oborn and E. C. Higgin-
son. Joint Rept. Field Crops Res. Branch, Agric. Res. Service,
U.S. Dept. Agric. and Bur. Reclamation, U.S. Dept. Interior.

D. H. Matheson. Inter-
General Rept. to 2d Congress.

8p. Jan. 1954.
5. The role of algae in corrosion. H.C. Myers. Jour. Amer. Water
Wks. Assn. 39: 822-324. 1947.

6. Quality and quantity of plankton in the south end of Lake Michi-
gan in 1942. J. B. Lackey. Jour. Amer. Water Wks. Assn.
36: 669-674. 1944.

7. Plankton removal tests and potable water supply at Naval Sta-
tion, Newfoundland. C. M. Palmer and H. H. Black. Dept.
Health, Ed. and Welfare, Public Health Service, Robt. A. Taft

10.

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12.

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31,

San. Eng. Center, Cincinnati, Ohio, 60 p. (Mimeographed).

Jan. .1955.

. Covers for reservoirs for filtered waters and ground waters.

Amer. Water Wks. Assn., p. 248-245 in Water wks. practice.
Williams and Wilkins, Baltimore, Md. 1925.

. Algae and other natural sourees of tastes and odors in water

G. J. Turre. Chapt. 2 in Taste and odor control in
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supplies.
water purification.
Bull. 1955.

Algae control at Danbury, Connecticut. E. A. Tarlton.
New England Water Wks. Assn. 63: 165-174. 1949.

Investigation of an unusual natural water softening. D. W. Gra-
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Freshwater biological research and water supply. W. H. Pearsall.
Jour. Inst. Water Engrs. 5: 482-484. 1951.

The Florida gulf coast red tide. J. B. Lackey and J. A. Hynes.
Florida Eng. and Indust. Exp. Sta. Bull., Series No. 70, 28 p.
Feb. 1955.

Mussel poisoning—a summary. H. Sommer and K. F. Meyer. In
Manual for control of communicable diseases in California.
California State Dept. Public Health. 1948.

Public health significance of paralytic shellfish poison: a review
of literature and unpublished research. E. F. McFarren, M. L.
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Schantz. Proc. National Shellfisheries Assn. 47: 114-141.
1956.

Two new species of Gymnodinium isolated from the Plymouth
area. D. Ballantine. Jour. Marine Biol. Assn. United Kingdom
35: 467-474. 1956.

Marine algae from Palmyra Island with special reference to the
feeding habits and toxicity of reef fishes. E. Y. Dawson, A. A.
Aleem, and B. W. Halstead. Allan Hancock Foundation Publ.
Univ. Southern California. Occasional paper No. 17. 39 p.
Feb. 1955.

Treatise on the British freshwater algae. Revised Ed. (p. 451).
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bridge, England, 534 p. 1927.

Observations on toxic marine algae. R. C. Habekost, I. M. Fraser,
and B. W. Halstead. Jour. Washington State Acad. Sci. 45: 101-
103. 1955.

Jour.

. Conditions which determine the efficiency of ammonium sulfate in

the control of Prymnesium parvum in fish breeding ponds. M.
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Cutaneous sensitization to blue-green algae. S. G. Cohen and
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Symptoms of hay fever caused by algae. II. Microcystis, another
form of algae producing allergenic reactions. H. A. Heise.
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The role of algae and plankton in medicine. M. Schwimmer and
D. Schwimmer. Grune and Stratton, N.Y., 85 p. 1955.

Epidemic of intestinal disorders in Charleston, West Virginia, oc-
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Unusually mild recurring epidemic simulating food infection. R.

R. Spencer. Public Health Repts. 45: 2867-2877. 1930.
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The use of copper sulfate as a cure for fish diseases caused by
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How to know the Protozoa. F. L. Jahn.
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Wm. C. Brown Co.,
''CHAPTER XI

ADDITIONAL USES FOR

ALGAE FOUND IN

REFERENCE has already been made (ch. VI) to the utili-
zation of algae as indicators of domestic sewage pollution and
of natural purification in streams. They are also considered
useful as indicators of the sources of a particular water
supply, the pollution of ground water supplies with surface
water, the progress of sewage change in oxidation ponds, the
pollution of marine and estuarine waters, the pH and tem-
perature ranges of a stream or lake, the toxicity of industrial
wastes, and the relative abundance in water of chemicals
such as sodium chloride, iron, and calcium phosphate.

INDUSTRIAL USES

Algae also constitute the raw materials used commercially
in the manufacture of sodium alginate, agar, iodine, diato-
maceous earth, and various food products. The food prod-
ucts known under various names such as amanori, kombu,
kan-ten, carrageen, dulse, and limu are an important part
of the diet in Hawaii, Japan, China, the Philippines, Ireland,
and several other areas. These products are derived prin-
cipally from marine algae.

The utilization of fresh-water algae in large amounts
awaits the development of practical methods for their mass
culture and harvesting (1). Their potential value as pro-
ducers of concentrated protein, carbohydrate, and fat is very
great, for there is no waste in the form of fibrous or woody
portions that are always present in land plants. The cheap-
est source of nutrients for their mass culturing is undoubt-
edly sewage and organic industrial wastes. Investigations
are now under way to develop practicable methods for the
utilization of sewage in the production of algae that would be
suitable for animal feeds, fertilizers, and other products (2).
Algae may serve in the near future as commercial sources
for vitamins, hormones, and antibiotics (3). It has been
estimated that, each year, about 5 million tons of algal nutri-
ents are wasted in the United States alone by present meth-
ods of sewage disposal (4). Where algae are grown in a
closed system for treatment of sewage, there need be no waste
of the nutrients.

ALGAE AS WATER SOURCE INDICATORS

It is often possible to determine the probable source of a
sample of surface water through a determination of the num-
ber and kinds of algae and related organisms present. This
is possible because the number and kinds of microorganisms
which develop are related to the hydrographic features of

496792 O-59—6

WATER SUPPLIES

bodies of water. Six chief types of lakes, for instance, are:
(a) the hard water lake with an outlet; (b) hard water
landlocked lake; (c) soft water lake with an outlet; (d) soft
water landlocked lake; (e) acid bog lake; and (f) alkaline
bog lake.

The hard water lake with an outlet tends to have an algal
flora that is predominantly the blue-green-diatom type.
Typical components of this hard water landlocked lake in-
clude an equal abu: ‘ance of greens and blue-greens plus
some of the euglenoids and yellow-greens (Chrysophyta).
In the soft water lake with an outlet, the algal flora is pre-
dominantly composed of green algae and the total number is
low. The soft water landlocked lake has a scant algal flora
and the filamentous forms are practically nonexistent. This
type of lake may tend to produce blooms of blue-green algae,
but the number of species involved would still be small. In
an acid bog lake, a great variety of desmids will be present.
Certain particular species of blue-greens can be expected.
Plankton forms are not abundant but filamentous ones will
be well developed and common. The alkaline bog lake has
an algal flora which is poor both in numbers and kinds.
Hard water organisms such as Chara and Spirogyra crassa
and Spirogyra decimena are often abundant (6). A knowl-
edge of the typical algal floras of various lakes which repre-
sent the sources of a water supply will help, therefore, in
determining the breeding grounds of the particular algae
that interfere with the treatment or use of the water.

ALGAE IN WASTE TREATMENT SYSTEMS

Reference has been made in chapter VI to the use of algae
for production of oxygen in sewage stabilization ponds. Re-
search carried out in California (7) has indicated that the
determination of the number and kinds of the more abun-
dant algae in these ponds can be used as a reliable index of
the progress in oxidation of the sewage. If the effluent
contains principally Chlorella, the pond is assumed to be
working at or over its capacity. If it contains a mixed flora
the pond can handle a heavier load. Chlamydomonas is one
of the common forms in the mixed flora which develops when
most of the organic matter is gone and mineral nutrients
have been precipitated because of a high pH. Chlamydom-
onas, in turn, appears to excrete an organic compound which
again makes the minerals available for algal growth.

Examination of the pond effluent for its algal flora may,
therefore, be a useful tool for operators of sewage plants

55
''56 ALGAE IN WATER SUPPLIES

 

having sewage stabilization ponds. The microscopic ex-
amination would require only a few minutes, and no exten-
sive training is required to recognize the few types of algae
important here. It has not yet been determined whether the
procedure is applicable for use in all parts of the country.

Algae may also be put to use in the treatment of industrial
wastes. By selection and adaptation of particular strains
of algae as well as of molds, yeasts, and bacteria, it may be
possible to bring about, biologically, changes in industrial
wastes which otherwise might be toxic or in other ways
unsuitable for release into streams, lakes, or marine waters.
The use of algae would be particularly advantageous when
release of oxygen into the waste is one of the required fac-
tors (5). The process has already been developed for treat-
ment of oil wastes from refineries.

ALGAE AS MARINE POLLUTION INDICATORS

Pollution of estuaries and of coastal marine waters is
rapidly becoming a problem at bathing beaches and where
the ocean frontage is used for residences, for industry, and
for recreation. Pollution is also influencing the marine fish-
ing and shellfish industries.

As with fresh-water forms, severe pollution in salt water
first tends to reduce the marine algal population to a few of
the more resistant species, but the decomposition products,
in turn, stimulate a vigorous subsequent growth of algae.
In marine polluted areas in northern Europe, the sewage
pollution is reported to prevent the growth of the brown rock
weed, Fucus, while algae that are stimulated include Blin-
dingia minima, Enteromorpha, Ulva lactuca, Porphyra leu-
costicta, E'rythrotrichia carnea, Acrochaetium virgatulum,
Acrochaetium thuretii, and Calothria confervicola. In addi-
tion to these large sea-weed algae, microscopic planktonic
algae thrive in the polluted areas, causing a decrease in the
transparency of the water (8). The sea lettuce, Ulva latis-
sima, is stimulated to active growth by sewage in England
(9). Industrial pollution in an estuary, involving princi-
pally iron sulfate, stimulated the growth of the pollution
alga Chlorella variegata and caused the sensitive diatoms
Chaetoceros and Skeletonema to settle out (10).

Marine and brackish water diatoms are being studied to
determine their usefulness as indicators of pollution with
either domestic sewage or industrial wastes. One apparatus
for obtaining the diatoms from the water is a slide rack with
floats known as a diatometer (11). Its use is being studied
in both fresh and salt waters.

TEMPERATURE, pH AND TOXICITY

Several physical characteristics of water are influenced by
utilization of the water for industrial purposes. The largest
single industrial use is cooling, and the prospects are that
this use will increase very rapidly. In general, the various
classes as well as individual species of algae have minimum,
optimum, and maximum temperatures for growth. The
optimum temperature for diatoms is 18°-30° C., for green
algae, 30°-35° C., and for blue-green algae, 35°-40° C.,

 

according to Cairns (12). He reports that the diatom Gom-
phonema parvulum grew best at 22° C., and still showed
considerable growth at 34° C., while another diatom WVitzs-
chia linearis which grew best at 22° C. showed little or no
growth at 30° C. Temperature changes are considered more
important than any other environmental factor in influenc-
ing diatom growth (13). A few blue-green algae are capable
of growth at temperatures much higher than 40° C. The
optimum temperature for Oscillatoria filiformis is 85.2° C.
The types of algae found in a particular stream may be a
good indication of the range in temperature that the water
has experienced.

Change in pH of water due to industrial wastes or to
natural causes will also greatly modify the algal population.
Mine wastes tend drastically to lower the pH and reduce the
algal flora to a few acid-tolerant forms such as Huglena
mutabilis, Ochromonas, Chromulina ovalis, Lepocinclis
ovum, Cryptomonas erosa, and Ulothria zonata (14). Addi-
tional acid-tolerant algae are included in table 12.

The majority of algae grow best in water at or near the
neutral point of pH, but a considerable number, particularly
among the blue-green algae, develop readily or may even
grow best in water with a high pH. In cultures the optimum
for Anacystis (Microcystis) and for Coccochloris (Gloeo-
thece) (fig. 48) has been found to be pH 10, with little or
no growth below pH 8 (15).

Figure 48.—Coccochloris peniocystis.

 

Other physical factors such as light and turbulence also
play their part in determining the particular algal flora
that will develop or remain in the water.

In bioassays to determine the toxicity of pollutants in
water, certain kinds of fish and the crustacean Daphnia
are being used. Algae also are being considered for the
test. Some may become useful as indicators of toxicity,
especially in waters where the wastes reduce the D.O. below
that in which animals can survive. There is comparatively
little information available on the tolerance limits of partic-
ular species of algae for the various toxic pollutants.

Melosira varians may be the only dominant diatom in
streams polluted with oil (16). Iron, which is a pollutant
from steel mills may be toxic to most algae but the flagellates
Chromulina and Trachelomonas hispida (fig. 49) may re-
main active. Certain diatoms are also found in iron-rich
water, including many species of Z'wnotia and some large
forms of Pinnularia (16). Algae require a small amount

Figure 49.—Trachelomonas hispida.
''Additional Uses for Algae Found in Water Supplies 57

 

of iron for the production of their chlorophyll and most
algae grow best when the ferric oxide content of the water
is between 0.2 and 2.0 mg. per liter. Distinct toxicity fre-
quently is noted when it exceeds 5.0 mg. (17).

Copper is well known to be toxic to many algae, but some
species are reported to be resistant to limited concentrations
of this metal, including Cymbella ventricosa, Calothria
braunii and Scenedesmus obliquus (fig. 50). Others are
listed in tables 12 and 13.

Figure 50.—Scenedesmus obliquus.

 

Phenol at a concentration of 1.9 mg. per liter appears to
have no toxic effect on diatoms (18). Chromium, bromine,
and many dyes from textile operations are very toxic to
algae. Spondylomorum, Pediastrum (fig. 51), and Pan-
dorina are capable of developing in the presence of paper
mill wastes toxic to most algae (19). Distillery wastes may
limit the algal growth to a few forms such as Chlamydo-
botrys, Chlorogonium (fig. 52), and Chlorobrachis (20).
Hydrogen sulfide at a concentration of 3.9 mg. per liter is
toxic to most diatoms. Four resistant species are Achnanthes
affinis, Cymbella ventricosa, Hanteschia amphioxys, and
Niteschia palea (18). Pollution of water in oil fields and
in salt works with salt brine composed largely of sodium
chloride may destroy most of the normal flora. Blooms of
marine or estuarine forms such as the green flagellate
Dunaliella may develop. Many diatoms and other algae
are tolerant to various concentrations of salt in water. Cer-
tain species of the following algae are reported to be re-
markably resistant to the. presence of chromium (21) : S#-
geoclonium, Tetraspora, Closterium, Niteschia, Navicula,
and Huglena.

  

Figure 52.—Chlorogonium eu-
chlorum.

Carefully controlled bioassay experiments with known
wastes and cultures of algae, followed by additional observa-
tions in polluted streams, should help in obtaining more
accurate information on the toxicity to algae of some of the
important industrial wastes.

REFERENCES

1. Some problems in large-scale culture of algae. H. W. Milner.
Sci. Monthly 80: 15-20. 1955.

2. Can sewage be converted into human food? L. G. Williams.
Furman Univ. Faculty Stud. 2 (No. 2) : 16-24. 1955.

3. Algal culture from laboratory to pilot plant. J. S. Burlew.
Carnegie Inst. Washington Publ. 600. 357 p. 1953.

4, Photosynthetic reclamation of organic wastes. H. B. Gotaas,
W. J. Oswald, and H. F. Ludwig. Sci. Monthly 79: 3868-379.
1954.

5. Specialized biological treatment opens new possibilities in treat-
ment of industrial wastes. W. B. Hart. Indust. and Eng.
Chem. 48: 983A-95A. Mar. 1956.

6. Lake types and algal distribution. G. W. Prescott. P. 13-33 in
his Algae of the western Great Lakes area exclusive of desmids
and diatoms. Cranbrook Inst. Sci., Bloomfield Hills, Mich.,
Bull. No. 31, 946 p. 1951.

7. General features of algal growth in sewage oxidation ponds.
M. B. Allen. California State Water Pollution Control Board,
Publ. No. 18. 1955.

8. The algal vegetation of Oslo Fjord. O. Sundene.
Vidensk. Akad., Norway. No. 2, 244p. 1953.

9. Treatment and disposal of industrial waste waters. B. A. South-
gate. British Govt. Dept. Sci. and Indust. Res., London,
England. 1948.

10. The effect of copperas pollution on plankton. C. C. Davis. No. 2
in his Studies of the effects of industrial pollution in the lower
Patapsco River area. Chesapeake Biolog. Lab. Publ. No. 72.
June 1948.

11. A new method for determining the pattern of the diatom flora.
Ruth Patrick, M. H. Hohn, and J. H. Wallace. Notulae Naturae,

Acad. Natural Sci. Philadelphia. No. 259, 12 p. July 1954.

12. Effects of increased temperatures on aquatie organisms. J.
Cairns, Jr. Indust. Wastes 1: 150-152. 1956.

13. Factors effecting the distribution of diatoms.
Bot. Rev. 14: 473-524. 1948.

14. Aquatic life in waters polluted by acid mine waste. J. B. Lackey.
Public Health Repts. 54: 740-746. 1939.

15. The mineral nutrition of Coccochloris peniocystis. G. C. Gerloff,
G. P. Fitzgerald, and F. Skoog. Amer. Jour. Bot. 37: 835-840.
1950.

16. Biological studies of polluted areas in the Genesee River system.
P. W. Claassen. Part 3 in A biological survey of the Genesee
River system. N.Y. State Dept. Conservation, Suppl. to 16th
Ann. Rept. for 1926. 1927.

17. Limnology. Revised Ed. P. S. Welch. McGraw-Hill, N.Y. 1952.
18. Die Algenfiora der Mulde. Bin Beitrag zur Biologie saprober
Fliisse. H. Schroeder. Pflanzenforschung 21: 1-88. 1939.

19. The use of biological indicators in determination of stream pollu-
tion. J. B. Lackey. Univ. Michigan School Public Health.
Lectures presented at Inservice Training Course in Sewage and
Indust. Waste Disposal. P. 109-118. (Mimeographed.) Mar.
1948.

20. The effects of distillery wastes and waters on the microscopic
flora and fauna of a small creek. J. B. Lackey. Public Health
Repts. 57 : 258-260. 1942.

21. An ecological study of the algae of the Saline River, Michigan.
J.L. Blum. Hydrobiologia 9: 361-408. 1957.

Skr. Norsk.

Ruth Patrick.
''58

ALGAE IN WATER SUPPLIES

 

Table 12.—Other Uses for Algae in Water Supplies

Problem and algae

Algae as water source indicators:
From hard water lake with an outlet:
Blue-green algae
Diatoms
Green flagellates :
Pandorina
Volvox
From hard water lake with no outlet:
Green algae
Blue-green algae
EKuglenoids:
Euglena
Phacus
Trachelomonas
Chrysophyta :
Synura uvella
Tribonema
From soft water lake with an outlet:
Desmids
Diatoms
From soft water lake with no outlet:
Green algae
From acid bog lake:
Desmids
Anacystis thermalis f. major
(Chroococcus prescottii)
Batrachospermum
Hapalosiphon pumilus
Microspora
Oedogonium
Scytonema ocellatum
From alkaline bog lake:
Chara
Spirogyra crassa
Spirogyra decemina

Algae as indicators of temperature range of waters:

Low temperature alge (18°-30° C.) :
Diatoms:
Gomphonema parvulum
Nitzschia filiformis
Nitzschia linearis

Medium temperature alge (30°-85° C.):

Green. alge

Warm temperature alge (35°-40° C.):

Blue-green algee

Hot temperature algz (40°-85° C.) :
Coccochloris (Synechococcus )
Lyngbya
Mastigocladus laminosus
Oscillatoria filiformis
Phormidium bijahensis
Phormidium geysericola
Phormidium laminosum

Algae indicating progress of change in sewage

oxidation ponds:
Chlamydomonas
Chlorella
Scenedesmus

Algae as indicators of marine and estuarine

pollution:
Acrochaetium thuretii
Acrochaetium virgatulum
Actinastrum hantzschii
Calothrix confervicola

> Chlorella variegata
Enteromorpha intestinalis
Enteromorpha prolifera
Erythrotrichia carnea
Porphyra leucosticta
Spirulina subsalsa
Ulva lactuca
Ulva latissima

Algal group

Blue-green
Diatom

Flagellate
Flagellate

Green
Blue-green

Flagellate
Flagellate
Flagellate

Flagellate
Yellow-green

Green
Diatom

Green

Green
Blue-green

Red
Blue-green
Green
Green
Blue-green

Green
Green
Green

Diatom
Diatom
Diatom

Green
Blue-green

Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green

Flagellate
Green
Green

Red

Red
Diatom
Blue-green
Green
Green
Green

Red

Red
Blue-green
Green
Green

Problem and algae

Algae as indicators of high acidity :

Actinella
Chlamydomonas
Chromulina ovalis
Cryptomonas erosa
Euglena adherens
Euglena hiemalis
Euglena mutabilis
Euglena stellata
Euglena tatrica
Euglena viridis
Hunotia exigua
Eunotia lunaris
Eunotia trinacria
Lepocinclis ovum
Navicula subtilissima
Navicula viridis
Ochromonas

Penium cucurbitinum
Pinnularia
Stauroneis anceps
Tabellaria flocculosa
Ulothrix zonata
Vanheurckia rhomboides var. crassenervia
Xanthidium. antilopeum

Algae indicating industrial wastes:

Copper:
Achnanthes affinis
Asterionella formosa
Calothrix braunii
Chlorococcum botryoides
Cymbella naviculiformis
Cymbella ventricosa
Navicula viridula
Neidium bisulcatum
Nitzschia palea
Scenedesmus obliquus
Stigeoclonium tenue
Symploca erecta

Paper mill wastes:
Amphora ovalis
Caloneis amphisbaena
Cocconeis diminuta
Cocconeis pediculus
Cymatopleura solea
Cymbella ventricosa
Diatoma vulgare
Gomphonema herculaneum
Navicula cryptocephala
Navicula radiosa
Oscillatoria
Pandorina
Pediastrum
Scenedesmus
Spondylomorum
Surirella ovata
Surirella ovata var. salina
Synedra pulchella
Synedra ulna
Ulothrix

Phenolic wastes:
Achnanthes affinis
Ceratoneis arcus
Cocconeis placentula
Cyclotella ktitzingiana
Cymatopleura solea
Cymbella naviculiformis
Diatoma vulgare
Fragilaria virescens
Gomphonema parvulum
Navicula cryptocephala
Neidium bisulcatum
Nitzschia palea
Pinnularia borealis
Surirella ovata
Synedra ulna

Algal group

Diatom
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Diatom
Diatom
Diatom
Flagellate
Diatom
Diatom
Flagellate
Desmid
Diatom
Diatom
Diatom
Green
Diatom
Desmid

Diatom
Diatom
Blue-green
Green
Diatom
Diatom
Diatom .
Diatom
Diatom
Green
Green
Blue-green

Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Blue-green
Flagellate
Green
Green
Flagellate
Diatom
Diatom
Diatom
Diatom
Green

Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
''Additional Uses for Algae Found in Water Supplies

59

 

Table 12.—Other Uses for Algae in Water Supplies—Continued

Problem and algae

Algae indicating industrial wastes :

Distillery wastes:
Chlamydobotrys
Chlorobrachis gracillima
Chlorogonium euchlorum

Oil:

Amphora ovalis

Diatoma vulgare
Gomphonema herculaneum
Melosira varians

Navicula radiosa
Surirella molleriana
Synedra acus

Synedra ulna

Hydrogen sulfide:
Achnanthes affinis
Caloneis amphisbaena
Camphlodiscus
Cyclotella meneghiniana
Cymbella ventricosa
Hantzschia amphioxys
Navicula minima
Neidium bisulcatum
Nitzschia ignorata
Nitzschia palea
Nitzschia tryblionella var. debilis
Surirella ovata var. salina

Iron:
Anomoeoneis serians var. brachysira
Chlorella variegata
Chromulina
Eunotia
Gomphonema acuminatum
Pinnularia microstauron
Pinnularia subcapitata var. hilseana
Stauroneis phoenicenteron
Stenopterobia intermedia
Surirella delicatissima
Surirella linearis
Trachelomonas hispida

Chromium :
Closterium acerosum
Huglena acus
Euglena oxyuris
Euglena sociabilis
Buglena stellata
Euglena viridis
Navicula atomus
Navicula cuspidata
Nitzschia linearis
Nitzschia palea
Stigeoclonium tenue
Tetraspora

Algal group

Flagellate
Flagellate
Flagellate

Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom

Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom

Diatom
Green
Flagellate
Diatom
Diatom ©
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Flagellate

Desmid
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Diatom
Diatom
Diatom
Diatom
Green
Green

Problem and algae

Algae indicating industrial wastes :
Salt brine (principally NaCl) :

Achnanthidium brevipes var. intermedia
Actinastrum hantzschii
Amphiprora paludosa
Amphora coffeiformis
Amphora ovalis
Anacystis
Calothrix
Chaetomorpha
Chlamydomonas ehrenbergii
Coecochloris elabens (Aphanothece
halophytica )
Cyclotella meneghiniana
Cymbella lacustris
Cymbella ventricosa
Diatoma elongatum
Diploneis elliptica
Dunaliella salina
Enteromorpha intestinalis
Enteromorpha prolifera
Entophysalis deusta (Aphanocapsa
littoralis)
Buglena
Frustulia rhomboides var. saxonica
Gomphonema
Gyrosigma attenuatum
Hantzshia elongata
Lyngbya astuarii
Melosira arenaria
Meridion circulare
Microcoleus chthonoplastes
Navicula anglica
Navicula cincta var. heufleri
Navicula cryptocephala
Navicula gregaria
Navicula longirostris
Navicula minuscula
Navicula pygmaea
Navicula salinarum
Navicula subtilissima
Nitzschia apiculata
Nitzschia epithemoides
Nitzschia frustulum
Nitzschia palea
Oscillatoria
Pediastrum simplex
Pinnularia
Phormidium tenue
Scenedesmus bijugatus
Spirulina subsalsa
Stephanoptera gracilis
Synedra acus
Synedra affinis
Synedra pulchella
Trachelomonas
Trichodesmium
Ulothrix

Algal group

Diatom
Green
Diatom
Diatom
Diatom
Blue-green
Blue-green
Green
Flagellate
Blue-green

Diatom
Diatom
Diatom
Diatom
Diatom
Flagellate
Green.
Green
Blue-green

Flagellate
Diatom
Diatom
Diatom
Diatom
Blue-green
Diatom
Diatom
Blue-green
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Blue-green
Green
Diatom
Blue-green
Green
Blue-green
Flagellate
Diatom
Diatom
Diatom
Flagellate
Blue-green
Green
''CHAPTER XII

PROCEDURES FOR ENUMERATION OF
ALGAE IN WATER

IT IS NECESSARY to know the purpose for which any
algological investigation is to be made before a particular
analytic procedure is selected. In some instances there may
be need to designate only certain particular groups or genera
or species of algae. This might be the case when analyzing
samples from oxidation ponds to determine the progress of
sewage change, or in analyzing stream samples for the pres-
ence of indicator algae or certain taste and odor algae. In
other situations, a knowledge of the number as well as the
general groups of algae may be required. This might be
needed to determine the most effective time for treating a
reservoir with an algicide. The total area or volume, par-
ticularly of the diatoms, would be useful data for determin-
ing the relationship of plankton to the length of filter runs.

For many treatment plants using surface water supplies,
adequate procedures would include periodic inspections of
the raw water supply, the treatment plant, and the distribu-
tion system for attached growths, and for floating mats and
blooms. This would be followed by laboratory examinations,
and recording of the dominant organisms present in these
visible growths of algae. In addition, plankton analyses of
water samples from these same areas would be made at
regular intervals. Information of this sort, especially when
taken over a period of time, and when supplemented by ade-
quate physicochemical data, is very valuable for determining
the type and application time of measures necessary for the
prevention and control of problems brought about by algae.

No method has yet been widely accepted as accurate for
reporting the number or volume of attached algae or of
those in floating mats. Observations can be recorded as
notes or indicated on an outline map to designate the loca-
tion and the extent of the areas of algal growths. Changes
in location and amount can then be followed by comparing
the notes or map records for different dates. Identification
of the algae can be accomplished with the aid of a micro-
scope and a key such as included in the appendix.

In the recording of plankton algae (1) the common pro-
cedure begins with the collection of a water sample from a
designated location and depth. When the sample is not
to be taken immediately to the laboratory for analysis, pres-
ervation is accomplished by the addition of formaldehyde.
The next step involves the concentration of the plankton in
the sample by means of a centrifuge or a Sedgwick-Rafter
sand filter. Using the concentrate, 1 ml. is placed in a Sedg-
wick-Rafter counting cell and enumeration of the organisms
is made with the aid of a compound microscope fitted with a

60

Whipple ocular micrometer. The magnification used is
commonly 100X obtained by means of a 10X ocular and 10X
objective. With microscopes calibrated for this type of
analysis the field of view, as delimited by the ocular microm-
eter, can be adjusted to cover 0.001 ml. of the concentrate.
The plankton organisms appearing in 10 fields are counted
and, from their total, the number of organisms per milliliter,
liter, or gallon of the unconcentrated water sample can be
calculated (2).

Quantitative records for each genus or species may be re-
ported separately as well as the totals for the major groups
of algae. The enumeration may be in number of cells, num-
ber of clumps (isolated cells plus colonies), areal standard
units, or cubic standard units. Several variations of the
clump count method are in use. No single method of enu-
meration has been selected as a standard procedure to be fol-
lowed by water treatment laboratories. However, the clump
count procedure is probably the simplest method and also
the basic one, since the others are often derived from it by
extrapolation.

The low magnification of 100X commonly used in count-
ing plankton, together with the loss of significant numbers
of algae during preservation and concentration of the sam-
ples results in plankton values lower than those actually
present. It has been estimated that many waters contain a
larger volume of minute nannhoplankton than of the larger
forms readily visible under low magnification. In one ex-

periment the use of a nannoplankton counting slide (fig. 53)
gave an average clump count of 3,055 algae per ml., while

 

Figure 53.—Nannoplankton counting slide.
''Procedures for Enumeration of Algae in Water 61

 

the count with the Sedgwick-Rafter slide was only 1,165
(3). When samples from four different water sources were
used, the count with the nannoplankton slide in each case
was significantly higher than with the Sedgwick-Rafter
slide because many small algae were missed by the lower
magnification used in the latter method.

A number of the pigmented flagellates and diatoms are
so small that the very high magnification of an oil immersion
objective lens is required for their identification and enu-
meration. Even the nannoplankton slide cannot be used with
the oil immersion lens because of the very short focal length
of that lens. However, if a drop of known volume of the
concentrate is placed on a standard microscope slide and
covered with a No. 1 cover glass so that the drop spreads out
to occupy the area beneath it, the organisms can be counted
for a known portion of this area, and an extrapolation may
then be made to indicate the number per ml. (4).

Special care may have to be taken to obtain accurate rec-
ords of some of the algal flagellates that are taste and odor
producers or that may be indicators of clean water. When
preserved in formalin they may be changed to such an extent
that they are difficult to identify (4). They become dis-
torted in form, or altered in color, and the flagella are lost.
This is true particularly of Cryptomonas, Chroomonas,
Rhodomonas, Chromulina, Synura, Uroglenopsis, Eudorina,
Mallomonas, and Merotrichia. Even Euglena may be so
distorted as to prevent its identification to species. Un-
preserved samples may be required, therefore, when accurate
records of these sensitive algae are needed.

Where there is special interest in enumerating all kinds
and sizes in a water supply, the usual procedures for plank-
ton enumeration may have to be modified. For the larger
forms (mesoplankton), a 100-liter water sample is passed
through a silk bolting cloth net, size 25, which has 200
meshes to the linear inch and apertures of 30-40 microns
width. The organisms caught by the net are then washed
into 5 percent formalin with a final volume of 100 ml. This
would give a concentration of 1,000 to 1, which might be too
high and need dilution for easier counting. Enumeration
may be accomplished with a 1-ml. sample in a Sedgwick-
Rafter slide using a magnification of 25X. The count should
be limited to organisms 30 microns or more in width or di-
ameter, which would involve principally the ciliates, crus-
tacea, and other animal forms rather than algae. Extra-
polation will depend on the actual sample concentration used.

The smaller forms of plankton can be obtained in num-
bers sufficient for counting by using the Foerst centrifuge for
concentrating the sample. At a speed in excess of 15,000
r.p.m., the 525 ml. is centrifuged at a flow such as to permit
its completion in 3 minutes. The concentrate can then be
washed into a bottle and the volume brought up to 20 ml.
This gives a concentration of 25-1 which may have to be
reduced for some samples if the algae are found to be too
numerous per field under the microscope.

Enumeration of the organisms in the concentrate would
be made first using the common procedure, with a Sedgwick-

Rafter slide under a magnification of 100X. A concentra-
tion providing from 10 to 100 organisms per microscopic
field tends to reduce the counting error, providing the range
in width or diameter of the organisms is 5 to 30 microns
(microplankton). The forms from 1 to 5 microns (nanno-
plankton) may be enumerated with much greater precision
by using a counting slide which permits the use of a magnifi-
cation of 430X. Some specialized work may require a
magnification of approximately 1000X.

The combined results of the three procedures can then be
summarized as follows:
No. per 100 ml

No. per ml
No. per ml

Net (meso-) plankton
Microplankton
Nannoplankton

A typical form for use in recording the results of the anal-
ysis for plankton algae is shown in figure 54:

ALGAL PLANKTON RECORD
Localityo< 22-2 < 22 Station No _--- Collected-_----_- 19:3) Bp:
Type of analysis (Meso-, Micro-, Nanno-)

 

Total | No. per

Organisms Number per field

 

(Diatoms) - ------------ Bes ove a2 lees cep eee
(Greens) 222 22225225122 oe eho oS SMe ea | eee een
(Blue-Greens) - --------- 2 eed sede ite] eel emia fe | ee siege
(Pigmented flagellates) - -|-_|--|--|--|--|--|--|--|--|--|------
Total-algae: +2222 Sean IR eee ee eee ee eae
Unpigmented forms_- --- ooh deh a close ai | ees
Total organisms. ------- SSCe NT ee eee ee
Pséudoplankton...: 22 2)2.)2 5) 2) eile |oatl tae lee

 

 

 

 

 

 

 

 

 

Grand total___--- |---|

 

Information by Collector:

1. Collected -by 2-22 22 2 se 1 Analyzed! by 2228525 =e ee
2° Depths oc cao oles 2. Dptecs cia tues ee ee
3. Volume of sample- --------- 3. Method of concentration -_--
4. Preservative (kind and amt.) - 4, Amt. of water concentrated _ -
5. Weather... =--.--.--+-+---- 5. Amt. of concentrate____----
6. Visible algal growths__----~-- 6. Concentration:
7. Water temp.------ pH----- 7. Type of counting cell__-----
8. ps ene oe eke He 8. Magnification used _ --------
10; Threshold No: Raw... _.. ~ ,% Area of microscopic field...

OS Sede ee ae oe 10. Factor for No. per ml_------
11. Length of filter run_-------- 11. Interpretation of results__---
12: Other: datao -o42 S22 soe 12. Treatment recommended ---

Figure 54.—Typical form of algal plankton record.

The interpretation of plankton records has seldom been
based on a predetermined set of criteria. There are, how-
ever, a number of aids for interpretation which at least have
a limited or localized use.

For example, a water source for which the environmental
factors are not too variable from year to year would tend to
produce similar amounts of algal growth each year. Ex-
perience indicates that this constitutes a useful working
basis. Pearsall et al. (5) make the following statement : “We
should expect, on this basis, that each year we might get
''62 ALGAE IN WATER SUPPLIES

 

algal growth that would tend to consist of a similar number
of cell divisions in succession, to show a similar rate of
growth and to yield a similar maximum number. It is clear
that the possibility of forecasting depends largely upon this
being approximately correct, as it appears to be.” Thus,
the plankton records of previous years may give good clues
as to particular times during each season when large num-
bers or particular types of interference organisms are likely
to appear.

Pearsall, et al. emphasize, in addition, the form and struc-
ture of particular plankters as indicative of whether their
numbers will inerease or decrease. They state “that popu-
lations of algae that are not growing or that are approach-
ing their numerical maximum tend to show certain changes
in appearance. When these changes can easily be recognized,
they afford useful indications of the end of a period of algal
growth. This is often extremely useful when the question
arises of whether or not to apply treatment.”

In some areas the plankton count of the raw water has
been correlated with the threshold odor test, and in one state
the plankton count of the raw water has been suggested as
a means of predicting the probable plankton count of the
finished water following coagulation and rapid sand filtra-
tion. (6).

The number of organisms and the number of areal stand-
ard units of organisms have been used to determine the
amount of trouble to be expected and the time when treat-
ment should begin. Thus, Whipple (7) stated that “when
organisms were less than 500 per cc. they would cause no
trouble; between 500 to 1,000 per cc., little trouble; between
1,000 and 2,000, noticeable trouble; between 2,000 and 3,000,
decided trouble; and above 3,000, trouble would be serious.”

At one treatment plant, where lake water was being used,
the length of the filter run was found to be reduced rapidly
with an increase in areal standard units of algae from 50
to about 300. When the areal standard units of algae were
50 the probable filter run was 70 hours; with 100 areal units,
the filter run dropped to 35 hours; with 200 units, 18 hours;
with 400 units, 11 hours; and with 1,000 units, 6 hours.

Recently a diatometer has been described for sampling the
diatom population of a stream (8). By enumerating and
identifying up to 8,000 or more diatom specimens obtained
from the diatometer, it is possible, through statistical
analysis, to determine the frequency distribution and to con-
struct a truncated normal curve for the sample. The height
and position of the mode, shape of the curve, number of
frequency intervals, number of observed species, number of
species in the theoretical universe, and number of specimens
required for construction of the curve are reported to be im-
portant in evaluating the data for indications of water pol-
lution. Thus, when the water is relatively free of pollution,

the number of species in the mode is high (generally between
20 and 28), the mode is located between the second and
fourth intervals, the curve covers only 10 or 11 intervals, the
number of observed species is generally between 120 and 180,
the theoretical universe contains from 150 to 210 species, and
the number of specimens required for the count is low (ap-
proximately 8,000).

In stream areas adversely affected by pollution the num-
ber of species in the mode, number of observed species, and
number in the theoretical universe will all be reduced in
varying amounts corresponding to the degree of pollution.

In stream areas slightly enriched by nontoxic organic ma-
terials, the height of the mode remains about the same as
that for the clean water station but the curve extends to the
right as a “tail.” With increased pollution or with toxic
materials also present, the height of the mode will decrease,
the “tail” will usually extend still farther, the curve may
cover as many as 14 to 16 intervals, and up to 40,000 speci-
mens must be counted before the mode is evident. It is due
to the fact that diatoms can be obtained in large numbers
in surface waters that this type of statistical analysis can
be made.

In summary, it is evident that among the many procedures
for enumeration of algae it is necessary to select those that
will produce the amount and kind of information needed for
satisfactory treatment and use of each particular water

supply.

REFERENCES

1. Biologic examination of water, sewage sludge, or bottom materials.
Part 6 in Standard methods for the examination of water, sew-
age and industrial wastes. Ed. 10. Amer. Public Health Assn.,
IN.Y,-* 2D5b.

2. Simplified procedures for collecting, examining, and recording
plankton in water. W. M. Ingram and C. M. Palmer. Jour.

Amer. Water Wks. Assn. 44: 617-624. 1952. .

3. A new counting slide for nannoplankton. C. M. Palmer and T. E.
Maloney. Amer. Soc. Limnol. and Oceanog., Special Publ. No. 21,
6 p. 1954.

4. The manipulation and counting of river plankton and changes in
some organisms due to formalin preservation. J. B. Lackey.
Public Health Repts. 53: 2080-2098. 1938.

5. Freshwater biology and water supply in Britain. W. H. Pearsall,
A. C. Gardiner, and F. Greenshields. Freshwater Biolog. Assn.
of the British Empire, Sci. Publ. No. 11, 90 p. 1946.

6. Numerical rating of water supplies. Section 14, table 1416, in
Manual of water supply sanitation. Minnesota Dept. Health,
Minneapolis, Minn. 1941.

7. Records of examination. Chapt. 6 in The microscopy of drinking
water. Hd. 4. G. C. Whipple, G. M. Fair, and M. C. Whipple.
J. Wiley and Sons, N.Y. 1948.

8. A new method for determining the pattern of the diatom flora.
Ruth Patrick, M. H. Hohn, and J. H. Wallace. Notulae
Naturae, Acad. Natural Sci. Philadelphia. No. 259,12 p. July
1954.
''CHAPTER XiIll

CONTROL

IT IS BETTER to anticipate and prevent problems from
algae than to delay until they become serious. Effective
control of algal growth requires adequate records as to the
numbers, kinds, and locations of algae in the water supply.
Control of algae applies variously to the raw water sup-
ply, to the treatment plant, and to the distribution system.
The use of algicides will be considered in more detail under
raw water applications, although similar procedures may
sometimes be applied in the other two control areas.

CONTROL IN RAW WATER SUPPLIES

The application of an algicide frequently is carried out to
prevent or destroy the excessive growths of algae which
occur as blooms, mats, or as high concentrations of plankton.
However, the algicide may sometimes be applied to control
relatively low concentrations of certain algae, such as
Synura and Uroglenopsis, which may cause trouble even in
small numbers.

Copper sulfate is the only algicide in common use in water
supplies at present, although chlorine may serve as an algi-
cide besides as a bactericide or an oxidizing agent. The
“blue stone” or copper sulfate is toxic to many algae at com-
paratively low concentrations, is ordinarily nonlethal to fish
at the strengths recommended, and is relatively inexpensive.
However, in alkaline waters, it precipitates quickly as cop-
per carbonate and more slowly as copper hydrate, and in
such instances is considered to be effective as an algicide only
for a short time following its application. Bartsch (1) em-
phasizes that the dosage should be dependent upon the alka-
linity of the water and states that the following rule has been
used successfully in various midwestern lakes: If the methyl
orange alkalinity is less than 50 p.p.m., the blue stone
(CuSO,-5H.0) is effective at the rate of 0.9 pound per acre-
foot. If the methyl orange alkalinity is greater than 50
p.p.m., the rate should be 5.4 pounds per acre. In the waters
with a high alkalinity the dosage is not dependent upon
depth since precipitation would make it ineffective below
the surface.

The various genera and species of algae are not all alike
in their reaction to copper sulfate and this factor has fre-
quently been neglected in determining the concentration of
the algicide to be applied. A number of the very minute
planktonic green algae are very resistant to the toxic effects
of blue stone. The stonewarts, Chara and Nitella, are also
considered to be resistant as are a few of the green flagellates
and some of the filamentous blue-green algae. The diatoms

OF ALGAE

as a group are relatively susceptible but they have often
developed in large numbers following the destruction of
other algae through treatment with copper sulfate.

Fortunately a considerable number of the taste and odor
and filter clogging algae are very susceptible even to low
concentrations of the algicide. All of the following inter-
ference algae are normally considered as being very suscep-
tible to copper sulfate: Asterionella, Fragilaria, Tabellaria,
Spirogyra, Ceratium, Dinobryon, Synura, Anabaena, and
Anacystis (Microcystis). A more complete list of the
genera of algae, grouped according to their reported suscep-
tibility to the toxic effect of copper sulfate is given
table 13.

The lowest concentration of copper sulfate which is toxic
for a particular alga also varies according to the abundance
of the alga, the temperature of the water, the alkalinity of
the water, the amount of organic material in the water, and
other factors. Thus, the listing of a specific concentration of
an algicide as the minimum effective dosage is not reliable
unless these other factors have first been taken into consider-
ation. In table 13, therefore, the grouping of the algae is by
very general ranges in the dosage required for treatment.
The information used in preparing table 13 was obtained
from several sources, including Hale (2), Cox (3), Prescott
(4), Maloney and Palmer (5), Pearsall et al. (6), and
Matheson (7).

There are a number of chemical groups which contain
compounds that are algicidal. The most promising of these
groups include the inorganic salts, organic salts, rosin amines,
antibiotics, quinones, substituted hydrocarbons, quaternary
ammonium compounds, amide derivatives, and phenols (8).
The chemicals, to be selected as satisfactory for use in domes-
tic water supplies, will have to be not only economically
feasible but also nontoxic to animal life and to plants other
than algae. Asthese will probably cost more per pound than
the algicides now in use, they will, therefore, be used only
where careful plankton records are kept, which would permit
early localized treatment to prevent undesirable species of
algae from increasing in number. <Algicides which are selec-
tively toxic to the algae which produce tastes and odors, mats
or blankets (fig. 55), blooms, slimes, and other undesirable
conditions, and clog filters would be particularly valuable.

A pretreatment basin may simplify the control of algae
and algal odors when the raw water has a high algal produc-
tivity. The algicide is released continuously into the water
as it enters the basin. Cement bafiles installed in the basin
and arranged alternately from the two sides forces the water

63
''64 ALGAE IN WATER SUPPLIES

 

to flow zig-zag through the basin before reaching the outlets.
For one supply in Wisconsin where this procedure has been
in use, the algal population is consistently and radically re-
duced. The threshold odor number also has been reduced an
_ average of 67 percent (9).

Continuous treatment with copper sulfate of Croton Lake
Reservoir in New York was established about 1925. The
copper sulfate dosage over a period of almost 20 years aver-
aged 0.18 parts per million (p.p.m.) and the overall reduc-
tion of plankton for this period was 65 percent (10).

A number of methods other than by algicides are in use
for the control of algae in raw water supplies. An increase
in turbidity due to silt will tend to reduce the phytoplankton
population by limiting the penetration of light that is essen-
tial for the growth of algae. Thus, in shallow reservoirs,
fish which stir up the bottom mud and make the water turbid
will aid in controlling plankton populations. <A turbidity
of 100 p.p.m. in rivers may be sufficient to cause plankton
algae to disappear but they quickly reappear as the turbidity
decreases (11).

Attached algae and water weeds can become a problem in
the shallow margins of lakes and reservoirs. When sodium
arsenite can not be employed, these forms are often difficult
to control (12). The common procedure is to cut them or
pull them out. One Connecticut utility riprapped the shore
of the reservoir in an attempt to eliminate their growth.

Mechanical removal of algae may be the simplest way of
disposing of massive growths which become detached and
washed ashore or which collect in localized areas of the res-
ervoir. This is of particular importance where the reservoir
or lake is used for recreational purposes as well as for do-
mestic water supply. Reduction in the amount of plankton
algae in a lake has been attempted by passage of the water
through a rapid sand filter, the filtered water being returned
to the lake (13). The backwash containing the algae collected
by the filter can be used as a land fertilizer or disposed of in
a lagoon.

For new reservoirs, clearing the site of vegetation and or-
ganic debris before filling will reduce the nutrients that
otherwise would be present to stimulate algal growths. For
all water supply reservoirs, provisions should be put into
effect as early as possible for keeping the inflow of nutrients
toa minimum. These would include measures for reducing
the runoff from agricultural land and the selection of a sup-
ply as free as possible of upstream sewage effluents and other
organic wastes. The degree of sewage treatment generally
has little or no effect in reducing the potential nutrient value
of the sewage for algae. Chemical methods of extracting ni-
trates, phosphates, and other nutrients from water are not
as yet considered to be economically practical.

When a reservoir receives its water from a stream there is
a period of time after which the stream plankton dies out in
the reservoir and before the reservoir plankton has had time
to develop. The ideal period of storage, as far as water with
a low plankton count is concerned, therefore, may be between
10 and 14 days (14) rather than a longer period of 28 to 30
days that has often been recommended in the past. It is not
often possible, of course, for the capacity of the reservoir to

be governed by this consideration.

The particular position and depth of the raw water supply
intake in a reservoir or lake often predetermines the quality
of the water which will enter the treatment plant. In order
to ascertain the optimum position and depth for the intake a
knowledge of the biological as well as the chemical and
physical characteristics of the water at various locations is
required. For one water supply in Europe, 3 years of in-
vestigations of plankton and water temperature indicated
that a depth of 60 meters was to be recommended for the
intake. This depth was below the area of greatest density of
plankton, and below the autumn thermocline and the strata
of greatest decomposition and mineralization of organic
matter. No important improvement in quality of water
would have been obtained by placing the intake at a greater
depth (15).

Table 13.—Relative Toxicity of Copper Sulfate to Algae

 

Group Very susceptible

Susceptible

Resistant Very resistant

 

ipiilespreens = se. obo Anabaena, Anacystis,
Aphanizomenon, Gom-
phosphaeria, Rivularia.
Green sleae. 2. Foo eS Closterium, Hydrodictyon,
Spirogyra, Ulothrix.

PItLOMS Asterionella, Fragilaria,
Melosira, Navicula.
Tabellaria.
Blapellates= 32 222. Dinobryon, Synura, Uro-
glenopsis, Volvox.

 

 

Cylindrospermum, Oscilla-
toria, Plectonema.

Botryococcus, Cladophora,
Coelastrum, Draparnal-
dia, Enteromorpha, Gloe-
ocystis, Microspora, Tri-
bonema, Zygnema.

Gomphonema,
Stephanodiscus, Synedra,

Nitzschia,

Ceratium, Cryptomonas,
Euglena, Glenodinium,
Mallomonas.

Nostoe, Phormidium_--- --- Calothrix, Symploca.

Characium, Chlorella, Chlo-
rococcum, Coccomyxa,
Crucigenia, Desmidium,
Golenkinia, Mesotaenium,
Oocystis, Palmella, Pe-
diastrum, Pithophora,
Staurastrum, Stigeodlo-
nium, Tetraedron.

Achnanthes, Cymbella, Nei-
dium.

Ankistrodesmus, Chara,
Elaktothrix, Kirchneriel-
la, Nitella, Scenedesmus.

Chlamydomonas, Peridini-
um, Haematococcus.

Eudorina, Pandorina.

 

 

 
''Control of Algae 65

 

 

Figure 55a.—Experimental testing of a potential algicide: Applying
the algicide to a blanket of algae.

CONTROL IN TREATMENT PLANTS

Control of algae in the water treatment plant involves
primarily the processes of coagulation, sedimentation, and
filtration. Well regulated coagulation with sedimentation
will often remove up to 90 percent of the algae, and in some
cases 95-96 percent removal has been reported. A similar
percentage of removal may occur in a rapid sand filter run
efficiently. Assuming 90 percent removal by each of the two
processes, 1,000 algae per ml. in raw water would be reduced
to 100 by coagulation and to 10 by filtration. However, if the
removal was only 70 percent in each case, the treated water
would still contain 90 algae per ml. The percentage removal
by coagulation tends to be low when the number of algae in
the raw water is low but the efficiency of the process can be
improved through the use of a coagulant aid such as activated
silica.

Treatment with chlorine is often carried out in the plant
primarily to destroy pathogenic organisms, but the dosages
commonly used are sufficiently high to be toxic also to many
algae. However, dead as well as living organisms can cause
tastes and odors and clog filters. Coagulation of motile algae
such as H’uglena may be improved by prechlorination. When
plain sedimentation is used, prechlorination will kill many of
the algae and facilitate their settling out, since their motility
is stopped and their buoyancy due to oxygen production in
photosynthesis is reduced.

A process known as micro-straining is being used in some
treatment plants particularly in England. This involves the
passing of the water through a finely woven fabric of stain-
less steel. The size of the openings in the mesh determines
the size of the plankton organisms removed from the water.
The micro-strainer is usually in the form of an open drum.
While it revolves, that portion exposed to air is back washed
with jets of water (16).

 

Figure 55b.—Experimental testing of a potential algicide: Result
of the test: Blanket of algae has disappeared.

CONTROL IN DISTRIBUTION SYSTEMS

Control of algae in the distribution system is generally
limited to the use of algicides in open reservoirs containing
treated water. A permanent control would involve covering
the reservoir to exclude light to prevent the algae from de-
veloping. Where covering is considered too costly, chlorine
or copper sulfate is required at least during the warmer
months. When the former is used certain chlorine-resist-
ant algae sometimes tend to become predominant. One of
these is a minute desmid belonging to the genus Cosmarium.
Most of the algae in the distribution system either develop
in the exposed reservoirs or are transient organisms remain-
ing in the water after its passage through the treatment
plant. The majority of the organisms capable of multiply-
ing in the pipes of the distribution system are not algae but
are heterotrophic forms represented by various bacteria,
fungi, protozoa, worms, copepods, and other small aquatic
animals.

TYPES OF CONTROL METHODS

Control of algae in water supplies thus may involve the
use of algicides; the mechanical cleaning of settling basins,
filters, intake channels, and reservoir margins; the modifi-
cation of coagulation, filtration, chemical treatment or lo-
cation of the raw water intake; and, finally, the modification
of the reservoir to reduce the opportunities for massive
growths. Control of tastes and odors and other algal prod-
ucts involves additional procedures such as the use of ab-
sorbents and the removal of organic deposits from settling
basins and distribution lines. Effective control of algae is
dependent upon adequate procedures for detecting their
presence and interpreting the significance of any change in
their numbers and kinds.
'' 

66 ALGAE IN WATER SUPPLIES
REFERENCES 9. Pre-treatment basin for algae removal. A. J. Marx. Taste and
Odor Control Jour. 17 (No. 6) : 1-8. 1951.
1. Practical methods for control of algae and water weeds. A. F. 10. Methods of controlling aquatic growths in reservoirs. B. C.
Bartsch. Public Health Repts. 69: 749-757. 1954. Nesin and R. L. Derby. Jour. Amer. Water Wks Assn.
2. The use of copper sulphate in control of microscopic organisms. 46: 1141-1158. 1954.
¥F. E. Hale. Phelps Dodge Refining Corp., N.Y. 1950. 11. Plankton ecology of the Licking River, Ky. J. B. Lackey. U.S.
3. Water supply control. C. R. Cox. N.Y. State Dept. Health, Public Health Service, San. Eng. Div., Water and Sanitation
Bur. Environmental San., Bull. 22, 279 p. 1952. Investig. Cincinnati, Ohio. 14 p. (Mimeographed.) 1942.
4. Objectionable algae and their control in lakes and reservoirs. 12. A study in the chemical control of aquatic vegetation. M. M.
G. W. Prescott. Louisiana Municipal Rev. 1, Nos. 2 and 3. Boschetti. Sanitalk 5 (No.2) : 21-25. 1957.
1938. : 18. Control of algae, a means of prolonging the life of lakes. H. C.
5. Toxicity of six chemical compounds to thirty cultures of algae. Leibee and R. L. Smith. Wastes Eng. 24: 620-621. 1953.
cr Rigas . C. M. Palmer. Water and Sewage Wks. 14. The reservoirs of the Metropolitan Water Board and their in-
, ae : : nah fluence upon the character of the stored water. E. W. Taylor.
6. Freshwater biology and water supply in Britain. W. H. Pear- i :
i : Proe. International Assn. Theoretical and Appl. Limnol.
sall, A. C. Gardiner, and F. Greenshields. Freshwater Biolog.
Assn. of the British Empire, Sci. Publ. No. 11, 90 p. 1946. Se ee oe pat
7. The effects of algae in water supplies. D. H. Matheson. Inter- 15. The limnological conditions for a large water-supply intake on
national Water Supply Assn., General Rept. to 2d Congress, the Uberlinger Lake (Lake Constance). R. Muckle. Gas-u
Paris, France. 82 p. 1952. Wasserfach 97 : 213-222. 1956.
8. Evaluation of new algicides for water supply purposes. C. M. 16. Micro-straining. P. L. Boucher. Jour. Institution Water Engrs.
Palmer. Jour. Amer. Water Wks. Assn. 48: 1183-1137. 1956. 9: 561-595. 1955.
''Appendix

Key
Glossary
Bibliography

Genus and Species Index
''la.

| 1b.

2a.
~ Qb.
3a.
3b.
4a.
4b.

J 5a.
x 5b.
6a.
6b.
Ta.
Tb.
8a.

8b.
9a.

9b.
10a.

10b.
lla.
11b.

12a.
12b.
18a.
13b.
14a.
14b.
15a.
15b.

16a.

16b.

KEY TO ALGAE OF IMPORTANCE
IN WATER SUPPLIES

Plant a tube, thread, strand, ribbon, or membrane;

frequently visible to the unaided eye________-- 2.

Plants of microscopic cells which are isolated or in
irregular, spherical, or microscopic clusters;
cells not grouped into threads__--____________

Plant a tube, strand, ribbon, thread, or membrane
ORL Or, CON eo 3

Plant a branching tube with continuous proto-

123

plasm, not divided into cells____._..__________ 120
Plant a tube, strand, ribbon, thread, or a mat of

SESE 22 aa eee irae eee +
Plant a membrane of cells one cell thick (and two

OMTRIONG Celio Ide) 25s 116

Cells in isolated or clustered threads or ribbons
which are only one cell thick or wide___-__--__ 5
Cells in a tube, strand, or thread all (or a part) of

which is more than one cell thick or wide______ 108
Peplepecyes piesent coe 6
Pee MOR 23
Threads gradually narrowed to a point at one end_ t
Threads same width throughout_______-_________ 12
Threads as radii, in a gelatinous bead or mass____ 8
Threads not in a gelatinous bead or mass________ Lt
Spore (akinete) present, adjacent to the terminal

MUON
No spore (akinete) present____________
Gelatinous colony a smooth bead

(Gloeotrichia) 9
(Rivularia) 10

Gloeotrichia echinulata

Gelatinous colony irregular____--_- Gloeotrichia natans
Cells near the narrow end as long as wide

Rivularia dura

Cells near the narrow end twice as long as
Rivularia haematites
Cells adjacent to heterocyst wider than hetero-
Calothria braunii
Cells adjacent to heterocyst narrower than heter-

Ocyst nw a es Calothrix parietina
Branching: present ioe. eo ee ee 13
Branechine absent 25 oo 14

Branches in pairs__------ Scytonema toly pothricoides
Branches arising singly_-------_- Tolypothrixa tenuis
Heterocyst terminal only____- (Cylindrospermum) 15
Heterocysts intercalary (within the filament) --- 16
Heterocyst round__------ Cylindrospermum muscicola
Heterocyst elongate_______ Cylindrospermum stagnale
Threads encased in a gelatinous bead or mass
(Nostoc) 17
Threads not encased in a definite gelatinous

mass 18

17a.
17b.
18a.
18b.

19a.
19b.
20a.

20b.
21a.

2b.
22a.
22b.
23a,
23b.
24a,

24b.
Q5a.
25b.
26a.

26b.

27a.
27b.

28a.
28b.
29a.
29b.
80a.
30b.
8la.
31b.

32a.

32b.
33a.

Heterocysts and vegetative cells rounded
Nostoc pruniforme
Heterocysts and vegetative cells oblong
Nostoc carneum
Heterocysts and vegetative cells shorter than the
thread wilt ooo os Nodularia spumigena
Heterocysts and vegetative cells not shorter than
thethread widths. 260 S20 19
Heterocysts rounded = es (Anabaena) 20
Heterocysts cylindric______ Aphanizomenon flos-aquae
Cells elongate, depressed in the middle; hetero-
bynes wate Anabaena constricta
Cells rounded; heterocysts common_-_------____ 21
Heterocysts with lateral extensions
Anabaena planctonica
Heterocysts without lateral extensions__________ 22
Threads 4-8 » wide__-_____ Bees Anabaena flos-aquae
Threads 8-14 » wide.____________ Anabaena circinalis

Dranchaig Wheaties. 6s 24
Branching (including “false” branching) present 84
Cell pigments distributed throughout the pro-
NOI os 25
Cell pigments limited to plastids______________ 49
Threads short and formed as an even spiral____ 285
Threads very long and not forming an even spiral 26

Several parallel threads of cells in one common

CRI i Microcoleus subtorulosus
One thread per sheath if present.____-_________ 27
Sheath or gelatinous matrix present____________ 28

No sheath nor gelatinous matrix appar-
(Oscillatoria) 35
Sheath distinct; no gelatinous matrix between
threads (Lyngbya) 29
Sheath indistinct or absent; threads inter-
woven with gelatinous matrix be-
(Phormidium) 32
Lyngbya ocracea
Coli ahor’t eyiiierig sc o5 00 er 30
Threads in part forming spirals__ Lyngbya lagerheimii

Threads straight or bent but not in spirals_____- 31
Maximum cell length 35 yw; sheath
RN i as tats Lyngbya digueti
Maximum cell length 6.5 »; sheath thick
Lyngbya versicolor
Ends of some threads with a rounded swollen
Gap COlle 222s oa ee ee 33
Ends of all threads without a “cap” cell_-______ 34
End of thread (with “cap”) abruptly
We Si ee Phormidium uncinatum
'' 

Key 69
33b. End of thread (with “cap”) straight 58a. Wall markings of two types, one coarse,
Phormidium autumnale ONG) HNG= eee ee os ae Bee 185
34a. Threads 3-5 » in width_-__-- Phormidium inundatum — 58b. Wall markings all fine----__-------- (Fragilaria) 54
84b. Threads 5-12 » in with_.________- Phormidium retzii 54a. Cells attached at middle _ portion
35a. Cells very short, generally less than one-third the as cau et cilia ee Fragilaria crotonensis
Me eNOLOR ok 36  54b. Cells attached along entire length__------~-~- 55
35b. Cells generally one-half as long to longer than 55a. Cell length 25-100 »_-___--_-_---- Fragilaria capucina
fee ween diameter. 39  55b. Cell length 7-25 p--__---_____- Fragilaria construens
36a. Cross walls constricted_____------ Oscillatoria ornata 56a. Plastid in the form of a spiral band__ (Spirogyra) 57
36b,. Cross walls not: constricted___-_22_.---L-..-__- 37. «6b. Plastid not a-apival bands) 61
37a. Ends of thread, if mature, curved__--------_- 38 S(a.. One-plastid per‘cell =o. ee ae 58
37b. Ends of thread straight__-------- Oscillatoria imosa 5b. Two or more plastids per cell___------------- 60
38a. Threads 10-14 » thick____--__-- Oscillatoria curviceps 58a. Threads 18-26 » wide----__-_-- Spirogyra communis
38b. Threads 16-60 » thick_--__--__- Oscillatoria princeps  58b. Threads 28-50 w wide--_--------------------- 59
39a. Threads appearing red to _ pur- 59a. Threads 28-40 p, wide_____---.--_- Spirogyra varians
Se. Oscillatoria rubescens 59b. Threads 40-50 » wide__-------- Spirogyra porticalis
39b. Threads yellow-green to blue-green_-__-------- 40 60a. Threads 30-45 yw wide; 3-4 plastids per
40a. Tareas -yellow-green._...._-.- -- 2-22. 41 BO et Spirogyra fluviatilis
40bs Threadsblue-ereen_--_____.-._-_____-_-_-_-___ 43  60b. Threads 50-80 » wide; 5-8 plastids per cell
41a. Cells 4-7 times as long as the thread diam- Spirogyra majuscula
_. CE GSS RE i le eee Oscillatoria putrida 61a. Plastids two per cell____-_--_------------_-- 62
41b. Cells less than four times as long as the thread 61b. Plastids either one or more than two per cell-_ _—66
NE she eee 42 62a. Cells with knobs or granules on the wall_____- 63
42a. Prominent granules (“pseudovacuoles”) in cen- 62b. Cells with a smooth outer wall_____- (Zygnema) 64
ter ofeach cell_.___._______ Oscillatoria lauterbornii 63a. Each cell with two central knobs on the wall
42b. No prominent granules in_ center of Desmidium grevillit
RN ee Oscillatoria chlorina _ 63b. Each cell with a ring of granules near one end
43a. Cells 144-2 times as long as the thread diameter__ 44 Hyalotheca mucosa
48b. Cells 2-3 times as long as the thread diameter__ 48 64a. Cells dense green, each plastid reaching to the
44a. Cell walls between cells thick and transpar- Swale ed eas Se ee ee ee Zygnema sterile
BE ARS Recipes ae Oscillatoria pseudogeminata  64b. Cells light green, plastids not completely filling
44b. Cell walls thin, appearing as a dark line_-___--__ 45 etlie Gl. 222 ee 65
45a. Ends of thread straight_-----__ Oscillatoria agardhti 65a. Width of thread 26-32 »; maximum cell length
45b. Ends of mature threads curved_____----------- 46 OOe mia ee Zygnema insigne
46a. Prominent granules present especially at both 65b. Width of thread 30-36 »; maximum cell length
ends of each cell. 2! o_o ssc. Oscillatoria tenuis TOO ete ee Zygnema pectinatum
46b. Cells without prominent granules__--------_-- 47 66a. Plastid a wide ribbon, passing through the cell
47a. Cross walls constricted____-_--- Oscillatoria chalybea 1es oo i ee (Mougeotia) 67
47b. Cross walls not constricted___-~- Oscillatoria formosa 66b. Plastid or plastids close to the cell wall
48a. End of thread long tapering--_ Oscillatoria splendida (parietal) 2258 shee 69
48b. End of thread not tapering_--_ Oscillatoria amphibia 67a. Threads with occasional “knee-joint” bends
49a. Cells separate from one another and enclosed in ; Mougeotia genuflexa
cE Hee i aaah anaes (Oymbella) 251b tb. Threads  straight_--------------------------- 68
49b. Cells attached to one another as a thread or rib- 68a. Threads 19-24 » wide; pyrenoids #10 Oey cell
Oa 50 Mougeotia sphaerocarpa
50a. Cells separating readily into discs or short cylin- i - Per = as
; ‘ . : ougeotia scalaris
ders, their circular face showing radial 69a. Occasional cells with one to several transverse
markings Bate ees a ene ae et 233a wall lines near one end____--___- (Oedogonium) 70
50b. Cells either not separating readily, or if so, no 60k. Geeasional terminal -tranevetea wall’ hae
circular end wall with radial markings__-_-- 51 not-yiveont.. "3
5la. Cells in a ribbon, attached side by side or by 70a. Thread diameter less than 24 p_--_---------_- 1
Memruepmiciess 6 ts ee 52. 0b. Thread diameter 25 » or morés: 2122-22 ok 72
51b. Cells in a thread, attached end to end__________ ' 56 71a. Thread diameter 9-14 p-______- Ocedogonium suectcum
52a. Numerous regularly spaced markings in the cell _ 71b. Thread diameter 14-23 p____--___- Oedogonium boscii
Soe ee 538 72a. Dwarf male plants attached to normal thread,
52b. Numerous markings in the cell wall ab- when reproducing_-__ Oedogonium idioandrosporum
SGlstec 2 a (Scenedesmus) 128  72b. No dwarf male plants produced__ Oedogonium grande
'' 

70 ALGAE IN WATER SUPPLIES
73a. Cells with one plastid which has a smooth 91b. Short branches on the main thread rebranched
BULLACO tse sa ee a ee a 74 twostosfour timess. 25) os es: Nitalla gracilis
73b. Cells with several plastids or with one nodular 92a. Terminal cells each with a colorless spine having
jE IG Er caer gee SM ner cetera ana Sel 78 an abruptly swollen base____-_- (Bulbochaete) 98
74a. Cells with rounded ends__-_-~- Stichococcus bacillaris 92b. No terminal spines with abruptly swollen bases_ 94
?#p. Colla with flat ends... 2.4... (Ulothrix) 75 93a. Vegetative cells 20-48 » long_-_. Bulbochaete mirabilis
75a. Threads 10 » or less in diameter____---_----___- 76 93b. Vegetative cells 48-88 » long --. Bulbochaete insignis
75b. Threads more than 10 » in diameter__-__-_----__ (ee 94a. Cells red, brown, or violet______ Audouinella violacea
76a. Threads 5-6 » in diameter__----_- Ulothrix variabilis 94b.; Célls greens. iis se i 95
76b. Threads 6-10 » in diameter__-_--_ Ulothria tenerrima 95a. Threads enclosed in a gelatinous bead or mass. 96
77a. Threads 11-17 » in diameter_______- VUlothria aequalis 95b. Threads not surrounded by a gelatinous mass__ 99
77b. Threads 20-60 » in diameter_____--_- Ulothria zonata 96a. Abrupt change in width from main thread to
78a. Iodine test for starch positive; one nodular branches? 20> 2258 0 a (Draparnaldia) 97
plemiie, per vel 79 96b. Gradual change in width from main thread to
78b. Iodine test for starch negative; several plastids branched ie ee oe (Chaetophora) 98
per cell_-__-_ 80 97a. Branches (from the main thread) with a central,
79a. Thread when broken, forming “H” shape seg- TAIOARIR Oe ee Draparnaldia plumosa
ments ~----------------------- Microspora amoena 97b. Branches diverging and with no central main
79b. Thread when fragmented, separating irregu- ete ee Draparnaldia glomerata
larly or between cells___-_---- (Zhizoclonium) 100a 98a. End cells long-pointed, with colorless tips
80a. Side walls of cells straight, not bulging. A pat- Chaetophora attenuata
tern of fine lines or dots present in the wall 98b. End cells abruptly pointed, mostly without long
but often indistinct___-------------- (Melosira) 81 colorless)tips) a. Gee Chaetophora elegans
80b. Side walls of cells slightly bulging. Pattern of 99a. Light and dense dark cells intermingled in the
wall markings not present__------- (Tribonema) 83 tiveness e Pithophora oedogonia
81a, Spine-like teeth at margin of end walls_______- 82 99b. Most of cells essentially alike in density------~- 100
81b. No spine-like teeth present___----__- M elosira varians 10a. Branches few in number, and short, colorless
82a. Wall with fine granules, arranged obliquely Rhizoclonium hieroglyphicum
Melosira crenulata —_100b. Branches numerous and green__-------------- 101
82b. Wall with coarse granules, arranged parallel to 101a. Terminal attenuation gradual, involving two or
BIGGS eee ey te Melosira granulata MOTE Cells. ets ee (Stigeoclonium) 102
83a. Plastids 2-4 per cell__--___--__---- Tribonema minus 101b. Terminal attenuation absent or abrupt, involv-
83b. Plastids more than four per cell ing only one cello. ec (Cladophora) 104
Tribonemabombycinum  102a. Branches frequently in pairs___________----_- 108
84a. Plastids present; branching “true”_---__------ 85 102b. Branches mostly single____- Stigeoclonium stagnatile
84b. Plastids absent; branching “false” 103a. Cells in main thread 1-2 times as long as wide
Plectonema tomasiniana Stigeoclonium lubricum
85a. Branches reconnected, forming a net 103b. Cells in main thread 2-3 times as long as wide
Hydrodictyon reticulatum Stigeoclonium tenue
85b. Branches not forming a distinct net__-__-__-_ . 86 104a. Branching often appearing forked, or in threes
86a. Each cell in a conical sheath open at the broad Cladophora aegagropila
ety eS ra (Dinobryon) 87  104b. Branches distinctly lateral_------------------ 105
OO Wo edtionl ehenth- around sacl wll) 99  105a. Branches forming acute angles with main
87a. Branches diverging, often almost at a right angle thread, thus forming clusters
Dis hisein diseneicie Cladophora glomerata
~ 7 150b. Branches forming wide angles with the main
87b. Branches compact often almost parallel____-___ 88 =
88a. Narrow end of sheath sh inted 89 UO 2
ee eee ne nee 106a. Threads crooked and bent____-_-__- Cladophora fracta
88b. Narrow end of sheath blunt pointed 106b, "Threads straight 2.00 ae 107
Dinobryon sertularia — 107a. Branches few, seldom rebranching
89a. Narrow end drawn out into a stalk Cladophora insignis
Dinobryon stipitatum — 107b. Branches numerous, often rebranching
89b. Narrow end diverging at the base__ Dinobryon sociale Cladophora crispata
90a. Short branches on the main thread in whorls of 108a. Plant or tube with a tight surface layer of
FOUN OLsMOres 222 Se (Nitella) 91 cells and with regularly spaced swellings
90b. Branching commonly single or in pairs____-_-- 92 Cp oo Lemanea annulata
91a. Short branches on the main thread rebranched 108b. Plant not a tube that has both a tight layer of

OT CO eee ees A oe ee Nitella flextlis

surface cells: and: nodesé. 22.2 net
''Key

eee

 

109a.
109b.
110a.
110b.
111a.
111b.
112a.
112b.
113a.
118b.
114a.
114b.
115a.
115b.
116a.

116b.
117a.

117b.
118a.
118b.
119a.
119b.
120a.

120b.
121a.

121b.
122.
122b.
123a.
123b.
124a.
124b.

125a.
125b.

Cells spherical and loosely arranged in a gela-
hinousematmxe 2250 oles Tetraspora gelatinosa

Cells not as loosely arranged spheres__---~-- 110
eiiabebrancned. 2023 a ble 111
Plants not branched____------ Schizomeris leibleinii
Clustered branching | -._.--.-._--_-_--_-__- 112
iemonehes-cinele.. i 115

Threads embedded in gelatinous matrix
(Batrachospermum) 118
No gelatinous matrix around the threads
(Chara) 114
Nodal masses of branches touching one an-
Batrachospermum vagum
Nodal masses of branches separated by a nar-
row space______--- Batrachospermum moniliforme
Short branches with two naked cells at the
i Chara globularis
Short branches with 3-4 naked cells at the
(Vi jpn eA gn Rl Chara vulgaris
Heterocysts present; platids absent
Stigonema minutum
Heterocysts absent; plastids present
Compsopogon coeruleus
Red eye spot and two flagella present for
erences) is ea
No eye spots nor flagella present___.____-----
Round to oval cells, held together by a flat
gelatinous matrix___---------. (Agmenellum) 131a
Cells not round and not enclosed in a gelatinous

Watering std 118
Cells regularly arranged to form an unattached

disc. Number of cells 2, 4, 8, 16, 32, 64 or 128_ 183b
Cells numerous; membrane attached on one

SMirice, 6 119

Long hairs extending from upper surface of
one Chaetopeltis megalocystis
No hairs extending from cell surfaces
Hildenbrandia rivularis
Constriction at the base of every branch
Dichotomosiphon tuberosus
No constrictions present in the tube. (Vaucheria) 121
Egg sac attached directly, without a stalk, to
the main vegetative tube__-__-___ Vaucheria sessilis
Egg sac attached to an abrupt, short, side
branch 122
One egg sac per branch____----- Vaucheria terrestris
Two or more egg sacs per branch_ Vaucheria geminata
Cells in colonies generally of a definite form

Wc arranoemont. foo ko 124
Cells isolated, in pairs or in loose, irregular

ONG Ses re i ee ee 173
Cells with many transverse rows of markings

punenvyn lic es bs ee 185
Cells without transverse rows of markings_--- 125
Cells arranged as a layer one cell thick_____-_- + 120
Cell cluster more than one cell thick and not

Tg 22% 7 RRS ise pane rue ERE ie oom Oh care 137

126a.

126b.
127a.

127b.
128a.

128b.
129a.
129b.
130a.

130b.

131a.

131b.
132a.

132b.

138a.

133b.
134a,
134b.
135a.
135b.
136a.
136b.

137a.
137b.

138a.

138b.
189a.

139b.

140a.

140b.
141a.
141b.
142a.

142b.
148a.

148b.
144.
144b.
145a.
145b.

146a.

Red eye spot and two flagella present for each
Colles Bo eee ee ae Gonium pectorale
No red eye spots nor flagella present__-------- 127
Cells elongate, united side by side in one or
tworrows. 22225 eee ee (Scenedesmus) 128
Cells about-as-long as:wide_=___._.2-_.2_. 2 13]
Middle cells without spines but with pointed
ends. so aes Scenedesmus dimorphus
Middle cells with rounded ends__---_---------- 129
‘Fermimal cells. with spines:-__ 225-02) Se 130
Terminal cells without spines___ Scenedesmus bijuga
Terminal cells with two spines each
Scenedesmus quadricauda
Terminal cells with three or more spines
Scenedesmus abundans
Cells in regular rows, immersed in colorless
matrix --__- (Agmenellum quadriduplicatum) 132
Cells not immersed in colorless matrix________ 133
Cell diameter 1.3-2.2 p
Agmenellum quadriduplicatum, tenwissima type
Cell diameter 3-5 p
Agmenellum quadriduplicatum, glauca type
Cells without spines, projections, or inci-
SlOnss 2. ee Crucigenia quadrata

Cells with spines, projections, or incisions____ 184
Cells rounded____.----__--- Micractinium pusillum
Cells angular____---____-_----_---- (Pediastrum) 135
Numerous spaces between cells____ Pediastrum duplex
Cells fitted tightly together-_____------------ 136
Cell incisions deep and narrow_--. Pediastrum tetras
Cell incisions shallow and wide

Pediastrum boryanum

Cells sharp-pointed at both ends; often arcuate. 138
Cells not sharp-pointed at both ends; not
arcuate: 2b ee ee 140,

Cells embedded in a gelatinous matrix
Kirchneriella lunaris
Cells not embedded in a gelatinous matrix____- 139
Cells all arcuate; arranged back to back
Selenastrum gracile
Cells straight or bent in various ways;
loosely arranged or twisted together
(Ankistrodesmus) 140
Cells. bent____------------ Ankistrodesmus falcatus
Cellsstraight. Ankistrodesmus falcatus var. acicularis
Flagella present; eye spots often present_____- 142
No flagella nor eyespots present________------
Each cell in a conical sheath open at the wide
(Dinobryon) 86a
Individual cells not in conical sheaths___-~_-- 143
Each cell with 1-2 long straight rods extend-
Wipes Chrysosphaerella longispina

No long straight rods extending from the cells__. 144
Cells touching one another in a dense colony__ 145
Cells embedded separately in a colorless matrix, 149
Cells arranged radially, facing outward___--- 146
Cells all facing in one direction_--_..--------- 147

Plastids brown ; eyespot absent____-__-
'' 

72 ALGAE IN WATER SUPPLIES
146b. Plastids green; eyespot present in each cell 166b. Outer matrix homogeneous__ Sphaerocystis schroeteri
Pandorinamorum 167a. Colonies angular___-_------- Gloeocystis planctonica
147a. Each cell with four flagella 16 7b; Colonies rounded==2 ss = Gloeocystis gigas.
Spondylomorum quaternarium 168a. Cells equidistant from center of colony
147b. Each cell with two flagella______- (Pyrobotrys) 148 (Gomphosphaeria) 169
148a. Eyespot in the wider (anterior) end of the cell 168b. Cells irregularly distributed in the colony---_ 172
Pyrobotrys stellata 169a. Cells with pseudovacuoles_ Gomphosphaeria wichurae
148b. Eyespot in the narrower (posterior) end of 169b. Cells without pseudovacuoles____------------ 170
OOo ee Pyrobotrys gracilis 170a. Cells 2-4 » in diameter ;
1492." Bilastids brown 222-02 = Uroglenopsis americana (Gomphosphaeria lacustris) 171
woo. elastids omeone 62s sote UN 150  170b. Cells 4-15 » in diameter___ Gomphosphaeria aponina
150a. Cells 16, 32, or 64 per colony_--_-___ Eudorina elegans = 171a. Cells spherical
150b. Cells more than 100 per colony__------------ 151 Gomphosphaeria lacustris, kuetzingianum type
151a. Colony spherical; each cell with an eyespot 171b. Cells ovate__ Gomphosphaeria lacustris, collinsti type
Volvox aureus 172a. Cells ovoid; division plane perpendicular to
151b. Colony tubular or irregular; no eyespots JONG axis eo es ee (Coccochloris) 286a
(Tetraspora) 109a _—172b. Cells rounded; or division plane perpendicular
152a. Elongate cells, attached together at one end; to Short axis 22265 ae (Anacystis) 286b
arranged radially______--___- (Actinastrum) 153 = 178a. Cells with an abrupt median transverse groove
152b. Cells not elongate, often sperical__----------- 154 OF WNCSiONe. 25 ee 174
158a. Cells cylindric_.__..__-__- Actinastrum gracillimum  178b. Cells without an abrupt transverse median
153b. Cells distinctly bulging------ Actinastrum hanteschit groove or incision: je 184
ee a ON 155 174a. Cells brown; flagella present
154b. Plastids absent; pigment throughout each pro- (armored flagellates) 175
CU he cee ane en 168  174b. Cells green; no flagella____-_---_--_- (desmids) 178
155a. Colonies, including the outer matrix, orange to 175a. Cell with three or more long horns
POC-DtOWR e220 Botryococecus braunit Ceratium hirundinella
155b. Matrix, if any, not bright colored; cell plastids 175b. Cell without more than two long horns___---- 176
VOGT oer ee 156 176a. Cell wall of very thin smooth plates
15Gai Colonies round ‘to oval: 22-2227 3 160 Glenodinium palustre
156b. Colonies not round, often irregular in form_--_ 157 176b. Cell wall of very thick rough plates
157a. Straight (flat) walls between adjacent cells (Peridinium) 177
(Phytoconis) 278a  177a. Ends of cell pointed____-_ Peridinium wisconsinense
157b. Walls between neighboring cells rounded_-_-_-- 158  17%b. Ends of cell rounded___-___-_- Peridinium cinctum
158a. Cells arranged as a surface layer in a large 178a. Margin of cell with sharp pointed, deeply cut
parte (ab (T'etraspora) 109a lobes or long epiivesU 179
158b. Colony not a tube; cells in irregular pattern___ 159  178b. Lobes, if present, with rounded ends______--_- 182
159a. Large cells more than twice the diameter of the 179a. Median incision narrow, linear_ Aficrasterias truncata
iis ence ek (Chlorococcum) 280b  179b. Median incision wide, “V” or “U” shaped
159b. Large cells not more than twice the diameter of (Staurastrum) 180
thersmalieelisec 2.3. eer is eS (Palmela) 281a 180a. Margin of cell with long spikes
160a. Cells touching one another; tightly grouped Staurastrum paradoxum
Coelastrum microporum 180b. Margin of cell without long spikes____-----__- 181
20D. Cots loosely grouped...o---- 2c. 5 655. 161  181a. Ends of lobes with short spines
161a. Colorless threads extend from center is colony Staurastrum polymorphum
ee ee 162 181b. Ends of lobes without spines
161b. No colorless threads attached to cells in colony. 164 Staurastrum punctulatum
162a. Cells rounded or straight, oval 182a. Length of cell about double the width
(Dictyosphaerium) 163 Euastrum oblongum
162b. Cells elongate, some cells curved 182b. Length a cell 1 to 114 times the width
Dimorphococcus lunatus (Cosmarium) 183 |
163a. Cells rounded___-_------ Dictyosphaerium pulchellum —188a. Median incision narrow linear__ Cosmarium botrytis
163b. Cells straight, oval. Dictyosphaerium ehrenbergianum —183b. Median incision wide, “U” shaped
a Rt NE eso ic oe eee senec-- 165 Cosmarium portianum
Be Cs OP Oocystis borget 184a. Cells triangular_________------ Tetraedron muticum
ighas Onesplastid=per cell: 2 vy 1662 ; 184b: Cells: not tiiamoulart=: 0 ee ee 185
165b. Two to four plastids per cell__ Gloeococcus schroeteri 185a. Cells with one end distinctly different from
166a. Outer matrix divided into layers__ (G@loeocystis) 167 the’ others 2b sa ea ee 186
'' 

496792 O-59—7

Key 13
185b. Cells with both ends essentially alike--------- 925  205b. Furrow present; gullet absent.. Rhodomonas lacustris
_186a. Numerous transverse (not spiral) regularly 206a. Plastids yellow-brown__----~-- Chromulina rosanoffi
: spaced wall markings present —---- (diatoms) 187  206b. Plastids not yellow-brown; generally green---- 207
186b. No transverse regularly spaced wall markings 193 20a. One plastid per cell_-------~--------------- 208
187a. Cells curved (bent) in girdle view 207b. Two to several plastids per cell_____---------- 211
Rhoicospheniacurvata  208a. Cells tapering at each end__ Chlorogonium euchlorum
187b: Cells not curved in girdle view-------------- 188° 208b. ‘Cells rounded to ovalei:2222 0S. ees 209
188a. Cells with both fine and coarse transverse 209a. Two flagella per cell__-_------ (Chlamydomonas) 210
ips ee Meridion circulare  209b. Four flagella per cell__--_-------- Carteria multifilis
188b. Cells with transverse lines all alike in thickness. 189 210a. Pyrenoid angular; eyespot in front third of cell
189a. Cells essentially linear to rectangular; one Chlamydomonas reinhardi
terminal swelling larger than the other 210b. Pyrenoid circular; eyespot in middle third of
(Asterionella) 190 celle 225 es Chlamydomonas globosa
189b. Cells wedge-shaped; margins sometimes wavy 211a. Two plastids per cell__..____-__- Cryptoglena pigra
(Gomphonema) 191 — 211b. Several plastids per cell_-------------------- 212
190a. Larger terminal swelling 114 to 2 times wider 212a. Cell compressed (flattened) ~-...----- (Phacus) 213
than the other__-------------- Asterionella formosa 212b. Cell not compressed _-_---------------------- 214
190b. Larger terminal swelling less than 114 times 213a. Posterior spine short, bent__~_~- Phacus pleuronectes
wider than the other__---- Asterionella gracillima  218b. Posterior spine long, straight____ Phacus longicauda
191a. Narrow end enlarged in valve view 914. ‘Cell margin rigid. ___-2- 5.24} ae ee 215
Gomphonema geminatum —_214b. Cell margin flexible-_-------------- (Fuglena) 217
191b. Narrow end not enlarged in valve view__----~- 192 15a. Cell margin with spiral ridges__------ Phacus pyrum
192a. Tip of broad end about as wide as tip of nar- 215b. Cell margin without ridges, but may have spiral
row end in valve view------ Gomphonema parvulum lines. 22 ooo ee ee (Lepocinclis) 216
192b. Tip of broad end much wider than tip of narrow 216a. Posterior end with an abrupt, spine-like tip
end in valve view_------- Gomphonema olivaceum Lepocinelis ovum
193a. Spine present at each end of cell__ Schroederia setigera  216b. Posterior end rounded_----------- Lepocinelis teata
193b. No spine . both ends of cell_ beta pn mn cm 194  917a. Green plastids hidden by a red pigment in the
194a. Pigments in one or more plastids___---------- 195 WH Euglena sanguinea
194b. No plastid; pigments een es ses ne 217b. No red pigment except for the eyespot.__-___- 918
ntophysalis lemaniae :
Be conical chenth. (Dinobryon) 86a 218a. a at least one-fourth the length of the a
Ieeh Cals mot-m 2 conical sheath.—--—-- ay 2 ive 218b. Plastids discoid or at least shorter than one-
196a. Cell covered with scales and long spines fourth the length of the cell 990
Mallomonas caudata niet : ee oa ae iy
196b. Cell not covered with scales and long spines__-- 197 219a. Plastids two per cell_--------------- Euglena agilis
197a. Protoplasts separated by a space from a rigid 219b. Plastids several per cell, often extending radi-
eneath (lorica)___.-.-_-....-._-___-_____. 198 ately from the center__...------~- Euglena viridis
197b. No loose sheath around the cells__------------ 202  220a. Posterior end extending as an abrupt colorless
198a. Cells compressed (flattened) -... Phacotus lenticularis SPIN 2224s ee 221
198b. Cells not compressed___--------------------- 199 220b. Posterior end rounded or at least with no color-
199a. Lorica opaque; yellow to reddish or brown Jes8 SPINGoUuc ce cece ee 299
; Trachelomonas er ebea 9914. Spiral markings very prominent and granular
199b. Lorica transparent; colorless to eae oor Euglenaspirogyra
SOCOCCUS . . . .
200a. Outer membrane (lorica) oval__ Ty ccous ovalis 2th Spire anneiines teily Pe ee :
200b. Outer membrane (lorica) rounded_-------- 201 Engi qoeg as
201a. Lorica thickened around openi a 222a. Small; length 35-55 p_------------ EBuglena gracilis
‘ pening :
Chrysococcus rufescens 222b. Medium to large; length 65 » or more_-__---- 223
201b. Lorica not thickened around opening _— ae ee Tenge Oe eo ae
Chrysococcus major 223b. Large in size; length 250-290 p_. Huglena ehrenbergit
202a. Front end flattened diagonally._..-----_--__- 903 224. Plastids with irregular edge; flagellum two
202b. Front end not flattened diagonally____.------ 206 times as long as cell____------ Euglena polymorpha
208a. Plastids bright blue-green_____~- (Chroomonas) 204 224b. Plastids with smooth edge; flagellum about one-
 203b. Plastids brown, red, olive-green, or yellowish. 205 half the length of the cell__-------- Euglena deses
204a. Cell pointed at one end____--- Chroomonas nordstetii  225a. Cells distinctly bent (arcuate) ; with a spine or
204b. Cell not pointed at one end__ Chroomonas setoniensis narrowing to a point at both ends__--------- 226
205a. Gullet present; furrow absent_-_. Cryptomonas erosa  225b. Cells not arcuate_--------------------------- 230
''74

226a.

226b.

227.
227b.

228a.
228b.

229a.
229b.

230a.
230b.
231a.
231b.
232a.
232b.
9334.

238b.
234a,.

234b.
935a.
235b.
236a.
236b.

237.
237b.
238a.
238b.
239a.
239b.
240a.
240b.
241a.
241b.

242a.
242b.

ALGAE IN WATER SUPPLIES

Vacuole with particles showing Brownian move-
ment at each end of cell. Cells not in
PER oa ca eek caus (Closterium) 227
No terminal vacuoles. Cells may be in clusters
OP COLONIC eae Riis ee Ce A ae 228
Cell wide; width 30-70 p____ Clostertum moniliferum
Cell long and narrow; width up to 5»
Closterium aciculare
Cell with a narrow abrupt spine at each blunt

ONE ois Ophiocytium capitatum
No blunt ended cells with abrupt terminal
a ee 229
Sharp pointed ends as separate colorless spines. 193a
Sharp pointed ends as part of the green
PROVO Lashes. 52 See ers gs 137a
One long spine at each end of cell__-________- 231
INojlono-terminal spines26 2 2 232
Cell gradually narrowed to the spine____---__- 137a
Cell abruptly narrowed to the spine
Rhizosolenia gracilis
A regular pattern of fine lines or dots in the
pW Sub ce ear ao eee Poe (diatoms) 233
No regular pattern of fine lines or dots in the
BE see a a ec 276
Cells circular in one (valve) view; short rec-
tangular or square in other (girdle) view__ 234
Cells not circular in one view__-------------- 240

Valve surface with an inner and outer (mar-
ginal) pattern of striae___-_--__ (Cyclotella) 235

Valve surface with one continuous pattern of
SHTMAOL ee a ek a (Stephanodiscus) 238

Cells small; 4-10 » in diameter__ Cyclotella glomerata

Cells medium to large; 10-80 » in diameter___ 236
Outer half of valve with two types of lines,
one lonexone shortscc ei is ae 237

Outer half of valve with radial lines all alike
Cyclotella meneghiniana

Outer valve zone constituting less than one-
half the diameter_______--_-- Cyclotella bodanica

Outer valve zone constituting more than one-
half the diameter____--._--~-- Cyclotella compta
Cell 4205... diameter 22222 bso ise 239
Cell 25-65 p» in diameter____ Stephanodiscus niagarae

Cell with two transverse bands, in girdle
Stephanodiscus binderanus

Cell without two transverse bands, in girdle

VIS We oe eo i eee Stephanodiscus hanteschii
@ellsflatsovales (cnc1 se anes (Cocconets) 241
Cells neither flat nor'ovalo 33 242
Wall markings (striae) 18-20 in 10

fhe LL Ee a aa) i Cocconeis pediculus
Wall markings (striae) 23-25 in 10

pee Ses eo os Cocconeis placentula

Cell sigmoid in one view_-------------_----- 243
Cell not sigmoid in either round or point ended
(valve) or square ended (girdle) surface
VLC ete se ee 244.

243a.

248b.
QA4a,

244b,
245a.

245b.
246a.

246b.
247.

247b.
248a.

248b.

249a,
249b.
250a.

250b.

251a.

251b.
252a.

252b.

2538a.

253b.

254a.

254b.

255a.
255b.
256a.
256b.
257.

257b.

258a.

258b.

259a.

Cell sigmoid in_ valve _ surface

Tae eh ee Gyrosigma attenuatum
Cell sigmoid in square ended (girdle) surface

VIOW 22 Se oo es Niteschia acicularis
Cell longitudinally unsymmetrical in at least

ONE VIO Wi a seco cams edatncare 245
Cell longitudinally symmetrical______________ 254
Cell wall with both fine and coarse transverse

lines:( striae and eusatae) 6. 246
Cell wall with fine transverse lines (striae) only. 247

Valve face about as wide at middle as girdle
Epithemia turgida
Valve face one-half or less as wide at middle as

pirdie face:).iicy i oo Rhopalodia gibba
Line of pores and raphe located at edge of

Valve faees ni a 248
Raphe not at extreme edge of valve face_____- 250

Raphe of each valve adjacent to the same girdle
PUN aoe Hantzschia amphioxys
Raphe of each valve adjacent to different girdle

surfaces isc 23 22s (Niteschia) 249
Cell:20-65-~¢Jong 2) es es Bee Nitaschia palea
Gell’ (0-180 p Tong 25 a es Niteschia linearis
Cell longitudinally unsymmetrical in valve

VALVE ss se 251
Cell longitudinally unsymmetrical in girdle

RO lh onan cache aa rcs Achnanthes microcephala
Raphe bent toward one side at the middle

Amphora ovalis

Raphe a smooth curve throughout__ (Cymbella) 252
Cell only slightly unsymmetrical____ Cymbella cesati

Cell distinctly unsymmetrical___---_--------- 258
Striations distinctly cross-lined; width 10-30 p
Cymbella prostrata
Striations indistinctly cross-lined ; width 5-12 p
Cymbella ventricosa
Longitudinal line (raphe) and prominent mar-
ginal markings near both edges of valve__-__. 255
No marginal longitudinal line (raphe) nor keel;
raphe or pseudoraphe median__------------ 257

Margin of girdle face wavy_----- Cymatopleura solea
Margin of girdle face straight__--- (Surirella) 256
Celliwidth:8=23 ps eos sce Surirella ovata
Cell width 40-60 p__------------ Surirella splendida

Girdle face generally in view and with two or

more prominent longitudinal lines. In valve

view, swollen central oval portion bounded by
(Tabellaria) 258
Girdle face with less than two prominent longi-
tudinal lines. In valve view, whole central
portion not bounded by a line_-_---_----_-_-
Girdle face less than one-fourth as wide as long
Tabellaria fenestrata

Girdle face more than one-half as wide as long
Tabellaria flocculosa

Valve face with both coarse and fine transverse
lines7 202 ee ee Diatoma vulgare
'' 

Key 9
259b. Valve face with transverse lines, if visible, alike 275b. Cells 90-120 times as long as wide; central area
Pe ee i 260 rectangular___--__ Synedra acus var. angustissima
260a. Valve face naviculoid; true raphe present__-_-_- 261 276a. Green to brown pigment in one or more plastids. 277
260b. Valve face linear to linear-lanceolate; true 276b. No plastids; blue and green pigments through-
epee Sen Ge ssa ote Ce 270 Out, protoplast. (20 au ye ee 284.
261a. Valve face with wide transverse lines (costae) 277a. Cells long and narrow or flat-___--_--__--___ 238
(Pivmdaria) 262 S17. Cells romidled. 278
261b. Valve face with thin transverse lines (striae)-._ 263  278a. Straight, flat wall between adjacent cells in
262a. Cell 5-6 w broad__________- Pinnularia subcapitata OOITIOG cle ee Phytoconis botryoides
262b. Cell 34-50 » broad_______________ Pinnularia nobilis — 278b. Rounded wall between adjacent cells in colonies. 279
263a. Transverse lines (striae) absent across trans- 279a. Cell either with 2 opposite wall knobs or colony
verse axis of valve face. Stawroneis phoenicenteron of 2-4 cells surrounded by distinct membrane
263b. Transverse lines (striae) present across trans- Or both. 22 ee 164a
verse axis of valve face___--__------------ 264  — 279b. Cell without two wall knobs; colony not of 2-4
264a. Raphe strictly median_------------ (Navicula) 265 cells surrounded by distinct membrane______ 280
264b. Raphe located slightly to one side__--------_- 252 980a. Cells essentially similar in size within the col-
265a. Ends of valve face abruptly narrowed to a beak ON ee ee 981
Navicula exigua var. capitata 280b. Cells of very different sizes within the col-
265b. Ends of valve face gradually narrowed______- 266 ony Hh posccene.
266a. Most of striations strictly transverse Vavicula gracilis =... Co ees . :
266b. Most of striations radial (oblique)_------____ 967  8la. Cells embedded in an extensive gelatinous ma-
267a. Striae distinctly composed of dots (punctae) trix_.___ SoS Sees P almella mucosa
Naviculalanceolata  281b. Cells with little or no gelatinous matrix around
267b. Striae essentially as continuous lines__________ 268 thom .--- so (Chlorella) 282
268a. Central clear area on valve face rectangular 282a. Cells rounded--..------._----..-----.-----_ 283
Nawiculagraciloides  282b. Cells ellipsoidal to ovoid___-__- Chlorella ellipsoidea
268b. Central clear area on valve face oval_________ 269 283a. Cell 5-10 » in diameter; pyrenoid indistinct
269a. Cell length 20-40 y; ends slightly capitate Chlorella vulgaris
Navicula cry ptocephala 283b. Cell 8-5 » in diameter ; pyrenoid distinct
269b. Cell length 30-120 »; ends not capitate Chlorella pyrenoidosa
Navicularadiosa  284a. Cell a spiral rod__--__--___-_______-_________ 285
270a. Knob at one end larger than at the other 284b. Cell not a spiral rod_.___-____---...._______ 286
(Asterionella) 189a — 985a. Thread septate (with crosswalls)_ Arthrospira jenneri
270b. Terminal knobs if present equal in size 285b. Thread nonseptate (without crosswalls)
_ (Synedra) 271 Spirulina nordstedtéi
21a. Clear space (pseudonodule) in central 286a. Cells dividing in a plane at right angles to the
ee {fo Synedra pulchella long axis__---_---_________ Coccochloris stagnina
27th. ni peendanodnle ™ central Se anna == 212 286b. Cells spherical or dividing in a plane parallel to
272a. Sides parallel in valve view; each end with an the ] . a His) 987
enlarged nodule___-_-------_---- Synedra capitata 987 als her eR LIP RET a ( aig is)
979b, Sides converging to the ends in valve view... 278 a. Cell containing pseudovacuoles____ Anacystis cyanea
273a. Valve linear to lanceolate-linear; 8-12 striae 287b. Cell not contaning pseudovacuoles------------ 288
ee Synedra ulna 288a. Cell 2-6 » in diameter ; sheath often colored
278b. Valve narrowly linear-lanceolate; 12-18 striae a Anacystis montana
ON 974  288b. Cell 6-50 » in diameter; sheath colorless_____- 289
2740. Valve 5-6 » wide--_-------_---_-___- Synedra acus 289a. Cell 6-12 » in diameter; cells in colonies are
274b. Valve 2-4 w wide_-_______-____--__-- 275 mostly spherical___-___-___- Anacystis thermalis
275a. Cells up to 65 times as long as wide; central 289b. Cell 12-50 » in diameter; cells in colonies are

area absent to small oval. Synedra acus var. radians

often angular... 23.5. 1. Anacystis dimidiata
''GLOSSARY

Actinomycetes. A group of branching filamentous bacteria,
reproducing by terminal spores. They are common in the
soil. Selected strains are used for production of certain
antibiotics.

Aeration. The mixing of water or other liquid with air, in-
cluding the absorption of air through the surface of the
liquid.

Aerobic. A condition involving the presence of free (ele-
mentary) oxygen in a medium such as water or sewage.

Algae (singular, alga), Comparatively simple plants con-
taining photosynthetic pigments. A majority are aquatic
and many are microscopic in size.

Algicide (or algaecide). A chemical highly toxic to algae
and satisfactory for application to water.

Alpha-mesosaprobic zone. Area of active decomposition,
partly aerobic, partly anaerobic, in a stream heavily pol-
luted with organic wastes.

Alternate branching. Only one branch per node or at any
one height on a filament or strand.

Anaerobic. A condition involving the absence of free (ele-
mentary) oxygen in a medium such as water or sewage.

Anterior. The front or forward end of an organism that is
capable of movement.

Aquatic. Living in water.

Arcuate. Moderately curved, like a bow.

Areal standard unit. An area of 400 square microns, used
as a unit in designating the amount of plankton in water.

Armored flagellates. Flagellates having a cell wall com-
posed of distinct, tightly arranged segments or plates. The
wall is generally thick, rough and brown.

Aromatic. A fragrant, spicy or pungent odor.

Attenuation. A continuous decrease in width of a filament,
often to a point or thin hair.

Back wash. The cleaning of a rapid sand or mechanical
filter by reversing the flow of water upward through it.

Bacteria (singular, bacterium). Simple one-celled but often
colonial microorganisms, typically free of chlorophyll, and
rigid in form. Their common method of reproduction is
by cell division. With few exceptions they live on organic
materials.

Benthic. Referring to aquatic organisms growing in close
association with the substrate.

Benthos (or benthon). Aquatic microorganisms capable of
growth in close association with the substrate.

Biological. Associated with or caused by living organisms.

Biology. The field of study dealing with living organisms.
It may be divided into the study of plants (botany) and of
animals (zoology).

Blanket algae. A mass of filamentous algae floating as a
visible mat at the surface of the water.

76

Bloom. A concentrated growth or aggregation of plankton,
sufficiently dense as to be readily visible.

Blue-green algae. The group Myxophyceae, characterized
by simplicity of structure and reproduction, with cells in
a slimy matrix and containing no starch, nucleus, or plas-
tids and with a blue pigment present in addition to the
green chlorophyll.

Bound carbonates. The nearly insoluble monocarbonates
present in water, where a balance is maintained between
the amounts of bound, half bound and _ unbound
carbonates.

Calibration. Determination of the dimensions of a line,
area or mass, present in an istrument such as a micro-
scope. It is accomplished by measurement with a known
scale.

Calyptra. A cap or lid on some terminal cells in certain
filamentous blue-green algae.

Capitate. Presence of a round cell at the end of a fila-
ment; a cell with a rounded enlarged end.

Cell. The organized ultimate unit of structure and growth
of a plant or animal. It is composed of a protoplast
which, in plants, is generally sourrounded by a cell wall.

Cell face. The particular surface of a cell which con-
fronts a person who is observing it under a microscope.

Cell sap. The watery fluid of a cell which may separate
from the gelatinous protoplasm to form one or more
vacuoles.

Cell wall. The rigid to semirigid, inert, permeable layer
of cellulose, silica or other material which surrounds, and
is in contact with, the protoplast of plant cells. It is to
be distinguished from the flexible, selectively permeable
surface membrane (ectoplast) of the protoplast, and the
capsule, sheath or lorica which may be outside of the
cell wall.

Centric. Refers to diatoms which are circular in form in
valve view and have radial striae.

Chlorophyll. Green photosynthetic pigment, present in
plant cells including the algae.

Chromatophore. A color-carrying body within a cell
protoplast.

Clean water zone. That area of water, in a polluted
stream, in which self-purification has been completed.
Coagulant aid. A substance which, when added with the

coagulant to water, improves the formation of floc.

Coagulation. The agglomeration of suspended or colloidal
matter in a liquid such as water, commonly induced by
addition to the water of a floc-forming chemical.

Colloidal. A condition involving particles dispersed in a
medium such as water which do not go into solution nor
do they settle out.
''Glossary 77

 

Colony. An isolated group of cells which have developed
together from a single origina] parent plant or repro-
ductive cell. Each cell is theoretically capable of life
activities independent of the others.

Constricted. The surface wall of a filament curved in-
ward to meet the cross walls, thus leaving grooves on the
surface of the filament.

Cooling tower. An enclosure for holding water while its
temperature is decreasing. The cooling tower is part of
a system which involves absorption of heat by the water
from some heat generating apparatus or machinery.

Costae (single, costa). Thick, rib-like striae in diatom
walls.

Cross walls. Transverse walls in a filament, dividing it into
units or cells.

Crustacea. Aquatic animals with a rigid outer covering,
jointed appendages and gills. Included are the water fleas
such as Daphnia and the copepoda such as Cyclops.

Cubic standard unit. A volume equal to 8,000 cu. microns
and used as a unit in designating the amount of plankton
in water.

Culture. A growth of microorganisms in an artificial
medium containing the necessary nutrients.

Desmids. Organisms belonging to the subgroup Desmid-
iaceae of the green algae and characterized by cells of
distinctive shapes one half of which corresponds in shape,
size and contents to the other half. In many desmids the
two “semicells” are connected by a short narrow tube
(isthmus).

Diatoms. Organisms belonging to the group Bacillario-
phyceae and characterized by the presence of silica in the
cell walls, which are sculptured with striae and other mark-
ings, and by the presence of a brown pigment associated
with the chlorophyll.

Dissolved oxygen (D.O.). The amount of elementary oxygen
present in water in a dissolved state. It is commonly re-
ported in parts per million (by weight), or milligrams per
liter, of oxygen in the water.

Distribution system. Pipes or other conduits through which
a water supply is distributed to consumers.

Elliptical. Narrowly oval in form, the greatest width being
across the middle rather than nearer one end.

Enrichment. The addition to water of substances which in-
crease the amounts of nutrients used by aquatic organisms
in their growth.

Epitheca. The slightly larger half of the two pieces of the
diatom wall. It fits as a flanged cover over the smaller but
otherwise corresponding “hypotheca.”

Eye piece (or ocular). The short cylindrical frame holding
a lens or combination of lenses, and fitting into the top of
the microscope tube.

Eye spot. A light sensitive, red to orange body within the
protoplast of a flagellate.

False branching (or pseudobranching). <A lateral outgrowth
initiated by a cross breakage of a filament, followed by the
protrusion through the sheath of one or both of the broken
ends of the filament.

False raphe (or pseudoraphe). A longitudinal clear space on
the valve face of a diatom, and bounded on both sides by
lines of striae.

Filament. <A linear series of cells, forming a thread, and held
together by their cell walls or sheath.

Filter. A bed of sand or related ingredients through which
water is passed to reduce the amount of solid and colloidal
material in the water.

Filter clogging. The settling of algae, silt and other sub-
stances from the water into the pores and on the surface
of a sand or other granular filter bed, thus reducing the
rate of flow of the water through the filter.

Filter run. The time between two successive washing opera-
tions of a rapid sand filter.

Filter skin (or Schmutzdecke). The scum or gelatinous
layer over the top of a slow sand filter and containing
various types of aquatic microorganisms.

Filtration. The process used in water treatment plants of
passing water through a granular medium such as sand
for the removal or reduction in amount of suspended or
colloidal matter.

Flagellum. A microscopic whip-like extension present on
many of the motile algae and protozoa.

Flavor. An inclusive term for odor plus the tongue sensa-
tions of taste, texture, and temperature of a substance.
Flexible. A solid or semisolid body capable of readily
changing its shape when subjected to variations in ex-

ternal factors.

Frustule. The cell wall of a diatom.

Fungus (plural, fungi). Simple plants without chlorophyll,
and in a broad sense including both the bacteria and the
molds, yeasts and mushrooms. The simpler forms are one
celled; the higher forms are branching filaments.

Furrow. A groove or trench on the side of the cell of cer-
tain flagellates.

Gelatinous matrix. Semisolid material surrounding the cell
wall, and for some algae, having a characteristic shape or
color.

Genus. A group (in the classification system for plants and
animals) into which are placed species that resemble one
another more than they do other species.

Girdle view. The side, rather than the front or top view,
of a diatom. It reveals the junction (girdle) of the
epitheca and hypotheca.

Green algae. Organisms belonging to the class Chlorophy-
ceae and characterized by photosynthetic pigments similar
in color to those of the higher green plants. The storage
food is starch.

Ground water. Water (excepting capillary water) located
below the surface of the ground, generally limited to that
below the water table.

Gullet. An internal sac-like cavity, open to the outside at
the anterior end of the cell. It is present in certain flagel-
lates.

Half bound carbonates. Somewhat soluble bicarbonates
present in water where a balance is maintained between
the amounts of bound, half bound and unbound carbonates.
''78 ALGAE IN WATER SUPPLIES

 

Hardness. Ability of water to form a curd-like scum when
soap is added and to form scale in boilers. It is caused
by presence in the water of carbonates, sulfates, and other
related substances.

Hay fever. Allergic symptoms involving the upper respira-
tory tract.

Healthy (portion of) stream. Flowing water in which the
aquatic life has not been adversely affected by human acti-
vities such as pollution or by other relatively recent
changes in the environment.

Heterocyst. A specialized cell in certain filamentous blue-
green algae. It is larger, clearer and thicker walled than
the regular vegetative cells.

Heterotrophic. Referring to organisms that for their metab-
olism are dependent upon organic matter supplied from
sources outside of their own bodies.

Hypotheca. The smaller or bottom half of the diatom cell
wall, its upturned, flanged edge fitting inside of a cor-
responding flange of the “epitheca.”

Impoundment. A reservoir used for collection and storage
of a water supply and for its controlled release as re-
quired for use.

Impurities in water. Foreign materials present in water,
particularly those impairing its usefulness.

Intercalary. Located between other structures rather than
at the end.

Katarobic zone. That area of a stream which is free of
both organic pollution and its products.

Key. A series of paired, contrasting statements each pair
leading to other pairs of statements and eventually reveal-
ing the names of organisms. It is for use in the identifi-
cation of algae and other plants and animals.

Lateral. Refers to the side, in contrast to the ends, of the
body of an alga or other organism.

Lorica. A rigid wall-like covering around a motile cell and
separated by a space from the protoplast or cell wall. An
opening is present at the anterior end, through which the
flagellum extends.

Loss of head. A decrease in water pressure due to friction
and commonly expressed in terms of the difference in ele-
vations to which water will rise in open tubes.

Mat. A layer of algae, generally of the filamentous type.
The layer may be either floating on the water or covering
a substrate.

Membrane. A wide, flat, thin plant body. A partition or
covering, such as the flexible, selectively permeable outer
surface film of a protoplast.

Metabolic. Referring to the building up (anabolic) and
tearing down (katabolic) processes going on within liv-
ing cells.

Micron. A unit of linear measurement appropriate for de-
scribing the dimensions of microscopic organisms. It is
equivalent to one one-thousandth of a millimeter.

Microorganism. Any minute organism either plant or ani-
mal, invisible or barely visible to the unaided eye.

Microscopic. An object too small to be clearly visible with-
out the aid of a microscope. a

Mold. Any fungus exclusive of the bacteria and yeasts

which is of concern because of its growth on foods or other
products used by man. |

Mu (uz). The Greek letter », pronounced “mw”, is used as
a symbol to indicate “micron” or “microns.”

Multicellular. An organism with sufficient specialization to
require more than one cell for its various growth
activities.

Nannoplankton. Unattached aquatic organisms which are
so small that very high magnification with the microscope
is required to make them clearly visible. The magnifica-
tion commonly used for them is 430 to 1,200X. :

Naviculoid. Having the form of a ship; pointed or wedge-
shaped at both ends, and widest at the middle.

Node. A swelling, generally occurring at equal distances
along the tube-like strands of certain algae.

Nonseptate. A tube-like body that is not subdivided by cross
partitions.

Nucleus. An organized, specialized body within the proto-
plast and containing the chromatin.

Nuisance organisms. Aquatic organisms that are capable of
interfering with the use or treatment of water.

Nutrient. A substance, such as a nitrate, absorbed by an or-
ganism and essential as a raw material for its growth.

Ocular (or eye piece). The lens or lens combination, fitted
into a short cylindric holder which, in turn, fits into the
top of the microscope tube.

Ocular micrometer. A glass disc, marked with a scale, that
fits on the diaphragm of the microscope ocular.

Odor. The property of a substance, receptive to the nose,
which permits pleasant or unpleasant sensations of fra-
grance or smells to be recognized.

Oligosaprobic zone. That area of a stream which contains
the mineralized products of self-purification from organic
pollution but with none of the organic pollutants re-
maining.

Opposite branching. With branches attached two per node
or at any one height on a filament, tube or strand.

Organism. A plant or animal. A body that has developed
asa result of being alive.

Outer matrix. The sheath or other cell material outside of
the cell wall.

Oxidation pond. An enclosure for sewage designed to pro-
mote the intensive growth of algae. These organisms re-
lease oxygen that stimulates transformation of the wastes
into inoffensive end products.

Oxygenation. The absorption by water of elemental oxygen
which has been released into the water by aquatic plants as
a waste product of photosynthesis.

Parietal. Located near or against the margin. A contrast-
ing term: “axial.”

Pennate diatom. A diatom which is elongate rather than
circular in the valve view. The wall ornamentation is ar-
ranged along the sides of the longitudinal axis rather than
about a central point.

Peripheral. Located at the margin.

Photosynthesis. Process of manufacture by algae and other
plants of sugar and other carbohydrates from inorganic
raw materials with the aid of light and chlorophyll.
''Glossary 79

 

Phytoplankton. Plant microorganisms, such as certain al-
gae, living unattached in the water. Contrasting term:
zooplankton.

Pigmented. Having color, particularly that due to the pres-
ence of photosynthetic colored material, in the cells of algae
and other plants.

Pigmented flagellates. Algae that are capable of swimming
and are furnished with one or more flagella. They belong
to a number of classes, including Euglenophyceae, Xantho-
phyceae, Dinophyceae, Chlorophyceae (Volvocales only)
and Cryptophyceae.

Pipe moss. A mat or mass of growth formed by aquatic
organisms that are attached to the inner surface of a water
pipe.

Plankton. Unattached aquatic microorganisms growing as
bodies dispersed throughout the water.

Plastid. A body in a plant cell that contains photosynthetic
pigments.

Pollution. Presence of foreign material in water, particu-
larly that which interferes with its use.

Polysaprobic zone. That area of a grossly polluted stream
which contains the complex organic waste matter that is
decomposing primarily by anaerobic processes.

Posterior. The hinder end of the body of a swimming
organism.

Potable. Referring to water which is drinkable as a result
of being free of pathogens, toxic materials, tastes, odors,
color and other undesirable physical, chemical and bio-
logical characteristics. |

Protoplasm. The gelatinous, colloidal material of plants
and animals in which all life activities occur.

Protoplast. The unit of protoplasm comprising one cell.

Protozoa. Unicellular animals, including the ciliates and
nonchlorophyllous flagellates.

Pseudonodule. A clear area resembling a swelling (nodule)
on a diatom wall.

Pseudoraphe (false raphe). A longitudinal clear space on
the valve face of a diatom and bounded on both sides by
striae.

Pseudovacuoles. Numerous minute bodies, resembling oil
globules, in cells of certain planktonic blue-green algae.
Their function and content are not fully determined. They
appear as black granules under high magnification.

Punctae. Pores (appearing as dots) arranged in rows
(striae) in diatom walls.

Pure culture. A growth in an artificial nutrient medium of
a single kind of microorganism and with no other kinds
of organisms present.

Pyrenoid. <A body, often within a plastid, around which
starch granules are aggregated.

Radii (Singular, radius). Lines extending from the center
of a circle and at right angles to tangents.

Raphe. A line (cleft) or clear space extending lengthwise
on the valve surface of a diatom. See true raphe and false
raphe.

Rapid sand filter. A bed of sand for water treatment con-
structed to permit a rapid rate of flow of water through it.

The rate is commonly from 2 to 3 gallons per minute per
square foot of filter surface.

Raw water. Water which is available as a supply for use
but which has not yet been treated or “purified.”

Reaeration. Contact of air with water permitting absorp-
tion of oxygen into the water from the air.

Recovery zone. The area of a stream in which active, pri-
marily aerobic, decomposition of the pollutants is occur-
ring.

Red algae. A class of algae (Rhodophyceae) most members
of which are marine. They contain a red pigment in
addition to the chlorophyll.

Red tide. A visible red to orange coloration of an area of
water caused by the presence of a bloom of certain
“armored” flagellates.

Reservoir. A basin, lake, pond, tank or impoundment which
is used for control, regulation and storage of water. It
may be either natural in origin or created by the building
of a dam or retaining wall.

Resting spore. <A specialized, thick walled reproductive cell,
capable of dormancy and of germination, without sexual
fusion, to form a new plant.

Rhodophyceae. <A class of algae popularly called “red
algae.” The cells contain a red pigment in addition to the
chlorophyll. Mostly marine forms.

Rigid. A structure with a fixed, nonflexible form.

Rotifer. A microscopic aquatic animal with a ciliated crown
attached to its head. The cilia give the appearance of
moving in a regular procession around the rim of the
crown.

Sand filter. A bed of sand through which water is permitted
to pass to reduce the amount of silt, plankton, colloidal
material and related substances that were present in the
water. It is in common use in water-treatment plants.

Saprophytic. The capability by some plants, including cer-
tain bacteria and molds, of utilizing dead organic matter
as nutrients.

Schmutzdecke. A German term for “filter skin”; the gelat-
inous layer over the top of a slow sand filter and contain-
ing various types of aquatic microorganisms.

Sedgewick-Rafter method. A procedure for the quantitative
determination of plankton in water, involving the use of a
special funnel and a special counting slide.

Sedimentation. A phenomenon used in water and sewage
treatment in which the rate of flow of the water is reduced
or stopped, permitting the settling out by gravitation of
the suspended particles.

Semirigid. A structure capable of limited change in form.

Sewage. The spent water supply after it has received the
various household, industrial and other wastes of a com-
munity.

Sewage treatment. Any artificial process to which sewage is
subjected in order to remove or reduce its objectional con-
stituents.

Slow sand filter. A bed of sand for water treatment con-
structed to permit water to flow through it at a relatively
slow rate. The rate is commonly from 3 to 6 million gal-
lons per day per acre of filter surface area.
''80 ALGAE IN WATER SUPPLIES

 

Stabilization. Biological transformation of organic wastes
into more durable metabolic end products.

Stabilization pond. An enclosure for sewage designed to
promote the intensive growth of algae. These organisms
provide oxygen that stimulates transformation of the
wastes into inoffensive end products.

Strand. A cylindrical, stem-like plant body that is more than
one cell thick.

Striae. Lines of pores (appearing as dots) arranged in a
regular pattern in the walls of diatoms.

Subspherical. Almost spherical.

Surface water. Water that rests upon the surface of the
earth in contrast to ground water.

Symmetrical diatom. Correspondence in shape, size and
relative position of parts of the two longitudinal or trans-
verse halves of a diatom.

Taste. A type of sensation (such as sweet or bitter) that the
tongue recognizes in addition to texture and temperature
of a substance.

Taxonomic. Emphasis on the classification and identifica-
tion of organisms.

Thallus. The plant body of an alga or fungus, composed
of one or more cells.

Threshold odor number. A unit designating the intensity of
odor in water as determined by its perception in a series
of dilutions with odor-free water.

Tongue sensation, The feel or texture that the tongue reg-
isters when in contact with water containing various
solutes. This is in addition to the sensations of taste and
temperature.

True branching. An elongated lateral growth initiated by
the longitudinal division of a marginal cell or cells in a
filament or strand.

True raphe. A slit (appearing as a line) extending almost
the length of the valve face of a diatom and interrupted
in the middle by a nodular area. The raphe is bounded
by a clear area which, in turn, is bounded by striae.

Tube. A thread-like plant body, one cell wide, that is not
divided into segments by cross walls.

Unbound carbonates. The soluble carbonic acid present in
water where a balance is maintained between the amounts
of bound, half bound and unbound carbonates.

Unialgal culture. A growth of only one kind of alga in an
artificial nutrient medium, but not necessarily free of
other types of microorganisms such as bacteria and pro-
tozoa.

Unicell. An organism composed of an isolated single cell.

Unicellular. One celled.

Unsymmetrical diatom. Lack of correspondence in shape,
size and relative position of parts in the two longitudinal
or transverse halves of a diatom.

Vacuole. An area within a protoplast which contains a
liquid such as cell sap or oil.

Valve view. The top surface, rather than the side, of the
epitheca or hypotheca of a diatom.

Water mites. Small, sometimes microscopic aquatic organ-
isms with a more or less round unsegmented body and
with four pairs of legs and one pair of palpi (processes
attached to the mouth).

Water quality. Those characteristics of a supply of water
which are important in determining its purity and use-
fulness to man.

Water table. The surface of a body of ground water when
its level is not confined by any overlying impermeable
layer of rock or soil.

Whipple micrometer. A subdivided square, marked off on a
glass disc, that fits into the microscope ocular. At a mag-
nification of 100X, in many microscopes, the square covers
approximately 1 sq. mm. of the microscope field. It is
designed for use in plankton counting.

Whorled branching. More than two branches per node or
at any one height on a filament or strand.

Yeast. Unicellular fungi which in general commonly re-
produce by budding, and ferment one or more carbohy-
drates with the production of gas.

Zooplankton. Protozoa and other animal microorganisms
living unattached in water.
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''82 ALGAE IN WATER SUPPLIES

 

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''GENUS AND SPECIES INDEX

Page references in boldface indicate the pages on which illustrations occur. Words in parentheses are synonyms.

Achnanthes, 11, 12, 36, 47, 64, 74

Achnanthes affinis, 57, 58, 59

Achnanthes microcephala, 12, 37, 48, 74

Achnanthidium brevipes var. intermedia, 59

Acrochaetium thuretii, 56, 58

Acrochaetium virgatulum, 56, 58

Actinastrum, 12, 20, 34, 45, 72

Actinastrum gracillimum, 12, 35, 46, 72

Actinastrum hantzschii, 12, 46, 58, 59, 72

Actinella, 58

Agmenellum, 10, 12, 14, 30, 32, 41, 71

Agmenellum quadriduplicatum, 9, 14, 71

Agmenellum quadriduplicatum, glauca type,
12, 33, 42, 71

Agmenellum quadriduplicatum,
type, 12, 31, 38, 71

Amphiprora paludosa, 59

Amphithrix janthina, 49

Amphora, 12, 74

Amphora coffeiformis, 59

Amphora ovalis, 12, 41, 42, 58, 59, 74

Anabaena, 10, 12, 15, 19, 20, 22, 26, 28, 30, 43,
51, 52, 53, 63, 64, 68

Anabaena circinalis, 12, 19, 51, 68

Anabaena constricta, 9, 12, 31, 38, 39, 68

Anabaena flos-aquae, 12, 23, 29, 51, 68

Anabaena lemmermanni, 51

Anabaena planctonica, 12, 19, 27, 68

Anabaenopsis, 20

Anacystis, 8, 10, 12, 14, 19, 20, 22, 26, 28, 30,
43, 51, 58, 56, 59, 63, 64, 72, 75

Anacystis cyanea, 9, 12, 14, 19, 27, 48, 51, 75

Anacystis dimidiata, 12, 14, 23, 29, 75

Anacystis montana, 12, 14, 31, 38, 49, 75

Anacystis thermalis, 12, 14, 46, 75

Anacystis thermalis f. major, 58

Ankistrodesmus, 12, 14, 32, 43, 64, 71

Ankistrodesmus faleatus, 12, 44, 46, 71

Ankistrodesmus faleatus var. acicularis, 12,
33, 42, 71 _

Anomoeoneis serians var. brachysira, 59

Aphanizomenon, 12, 15, 19, 20, 26, 43, 51, 64, 68

Aphanizomenon flos-aquae, 12, 19, 27, 51, 68

(Aphanocapsa ), 14, 51

(Aphanocapsa littoralis) , 59

(Aphanothece), 14

(Aphanothece halophytica), 59

Arthrospira, 10, 12, 30, 75

Arthrospira jenneri, 12, 14, 31, 38, 39, 75

Asterionella, 12, 19, 20, 22, 26, 28, 45, 51, 52,
63, 64, 73, 75

Asterionella formosa, 12, 23, 29, 58, 73

Asterionella gracillima, 12, 19, 27, 73

Audouinella, 10, 12, 14, 15, 36, 47, 70

Audouinella violacea, 12, 16, 37, 48, 70

tenuissima

Batrachospermum, 12, 36, 47, 51, 58, 71
Batrachospermum moniliforme, 12, 37, 48, 71
Batrachospermum vagum, 12, 41, 42, 71
Blidingia minima, 56

Botrydium, 10

Botrydium granulatum, 11

Botryococcus, 11, 12, 34, 45, 64, 72
Botryococcus braunii, 12, 35, 46, 72
Bulbochaete, 12, 15, 36, 47, 70
Bulbochaete insignis, 12, 37, 48, 70
Bulbochaete mirabilis, 12, 42, 70

Caloneis amphisbaena, 58, 59

Calothrix, 12, 32, 59, 64, 68

Calothrix braunii, 12, 48, 57, 58, 68

Calothrix confervicola, 56, 58

Calothrix parietina, 12, 33, 41, 42, 68

Campylodiscus, 59

Carteria, 12, 14, 30, 73

Carteria multifilis, 12, 31, 38, 73

Caulerpa serrulata, 51

Ceratium, 12, 19, 20, 26, 45, 51, 63, 64, 72

Ceratium hirundinella, 12, 19, 27, 72

Ceratoneis arcus, 58

Chaetoceros, 56

Chaetomorpha, 59

Chaetopeltis, 12, 71

Chaetopeltis megalocystis, 12, 42, 71

Chaetophora, 10, 12, 15, 36, 47, 51, 70

Chaetophora attenuata, 12, 48, 70

Chaetophora elegans, 12, 37, 48, 70

(Chamaesiphon), 14, 41

(Chamaesiphon incrustans), 14, 41

(Chantransia), 14, 47

Chara, 8, 10, 12, 20, 36, 47, 55, 58, 63, 64, 71

(Chara fragilis), 14

Chara globularis, 12, 14, 37, 48, 71

Chara vulgaris, 12, 19, 71

Characium, 49, 64

(Chlamydobotrys) , 14, 57, 59

Chlamydomonas, 12, 20, 23, 30, 39, 44, 49, 51,
55, 58, 64, 73

Chlamydomonas ehrenbergii, 59

Chlamydomonas globosa, 12, 19, 73

Chlamodomonas reinhardi, 12, 31, 38, 39, 73

Chlorella, 8, 10, 11, 12, 15, 20, 22, 28, 30, 39,
48, 51, 58, 55, 58, 64, 75

Chlorella ellipsoidea, 12, 46, 75

Chlorella pyrenoidosa, 12, 16, 23, 29, 38, 75

Chlorella variegata, 56, 58, 59

Chlorella vulgaris, 12, 31, 38, 39, 49, 75

Chlorobrachis, 57

Chlorobrachis gracillima, 59

Chlorococcum, 12, 14, 30, 39, 49, 51, 64, 72, 75

Chlorococcum botryoides, 58

Chlorococcum humicola, 12, 31, 38, 75

Chlorogonium, 12, 30, 57, 73

Chlorogonium euchlorum, 12, 31, 38, 57, 59, 73

Chromulina, 12, 32, 56, 59, 61, 73

Chromulina ovalis, 56, 58

Chromulina rosanoffi, 12, 33, 41, 42, 73

(Chroococcus) , 14, 22, 51

(Chroococcus limneticus), 14

(Chroococcus prescottii), 58

(Chroococcus turgidus), 14, 23

Chroomonas, 12, 61, 73

Chroomonas nordstetii, 12, 42, 73

Chroomonas setoniensis, 12, 42, 73

Chrysococcus, 10, 12, 15, 32, 42, 73

Chrysococcus major, 12, 42, 73

Chrysococcus ovalis, 12, 42, 73

Chrysococcus rufescens, 12, 33, 42, 73

Chrysosphaerella, 12, 20, 71

Chrysosphaerella longispina, 12, 19, 71

Cladophora, 12, 14, 18, 20, 32, 36, 41, 44, 47, 48,
49, 64, 70

Cladophora aegagropila, 12, 23, 70

Cladophora crispata, 12, 37, 48, 70<—

Cladophora fracta, 12, 46, 70

Cladophora glomerata, 12, 33, 42, 47, 48, T0<-—-

Cladophora insignis, 12, 19, 70

(Clathrocystis), 14, 19, 20

Closterium, 12, 20, 22, 28, 51, 57, 64, 74

Closterium acerosum, 59

Closterium aciculare, 12, 46, 74

Closterium lunula, 51

Closterium moniliferum, 12, 28, 29, 74

Coccochloris, 12, 14, 32, 56, 58, 72, 75

Coccochloris elabens, 59

Ccecochloris peniocystis, 14, 56

Coccochloris stagnina, 12, 33, 42, 75

Coecomyxa, 64

Cocconeis, 12, 32, 41, 74

Cocconeis diminuta, 58

Cocconeis pediculus, 12, 48, 58, 74

Cocconeis placentula, 12, 33, 41, 42, 58, 74

Coelastrum, 12, 34, 45, 51, 64, 72

Coelastrum microporum, 12, 35, 46, 72

(Coelosphaerium), 10, 14, 20

(Coelosphaerium kuetzingianum), 14, 51

(Coelosphaerium naegelianum ), 14

Compsopogon, 11, 12, 36, 47, 49, 71

Compsopogon coeruleus, 11, 12, 37, 48, 71

Cosmarium, 12, 20, 51, 65, 72

Cosmarium botrytis, 12, 46, 72

Cosmarium portianum, 12, 19, 72

Crucigenia, 12, 64, 71

Crucigenia quadrata, 12, 46, 71

Cryptoglena, 12

Cryptoglena pigra, 12, 38, 73

Cryptomonas, 12, 20, 42, 61, 73

Cryptomonas erosa, 12, 19, 56, 58, 73

Cyclotella, 8, 12, 15, 20, 22, 28, 32, 41, 44, 45,
51, 52, 74

Cyclotella bodanica, 12, 32, 42, 74

Cyclotella compta, 12, 19, 74

Cyclotella glomerata, 12, 46, 74

Cyclotella kuetzingiana, 58

Cyclotella meneghiniana, 12, 23, 29, 59, 74

Cylindrocystis brebissonii, 9

Cylindrospermum, 12, 15, 20, 34, 45, 64, 68

Cylindrospermum muscicola, 12, 19, 68

Cylindrospermum stagnale, 12, 35, 46, 68

Cymatopleura, 12, 74

Cymatopleura solea, 12, 48, 58, 74

Cymbella, 12, 14, 15, 22, 28, 36, 47, 51, 64, 69, 74

Cymbella cesati, 12, 42, 74

Cymbella lacustris, 59

Cymbella naviculiformis, 58

Cymbella prostrata, 12, 14, 37, 48, 74

Cymbella ventricosa, 12, 23, 29, 57, 58, 59, 74

85
''86

ALGAE IN WATER SUPPLIES

 

Desmidium, 12, 34, 45, 64, 69

Desmidium grevillii, 12, 35, 46, 69

Desmonema, 8

Desmonema wrangelii, 9

Diatoma, 11, 12, 14, 20, 22, 28, 51, 74

Diatoma elongatum, 59

Diatoma vulgare, 12, 19, 23, 29, 58, 59, 74

Dichotomosiphon, 12, 71

Dichotomosiphon tuberosus, 12, 23, 71

Dictyosphaerium, 12, 20, 72

Dictyosphaerium ehrenbergianum, 12, 19, 72

Dictyosphaerium pulchellum, 12, 23, 72

Dimorphococcus, 12, 72

Dimorphococcus lunatus, 12, 46, 72

Dinobryon, 10, 11, 12, 18, 19, 20, 22, 26, 28, 45,
51, 52, 68, 64, 70, 71, 73

Dinobryon divergens, 12, 19, 27, 43, 70

Dinobryon sertularia, 12, 23, 29, 70

Dinobryon sociale, 12, 46, 70

Dinobryon stipitatum, 12, 42, 70

Diploneis elliptica, 59

Draparnaldia, 12, 36, 47, 64, 70

Draparnaldia glomerata, 12, 37, 48, 70

Draparnaldia plumosa, 12, 42, 70

Dunaliella, 57

Dunaliella salina, 59

Egregia laevigata, 51

Elaktothrix, 64

Elaktothrix gelatinosa, 51

(Encyonema), 14, 47

(Encyonema paradoxum), 14

Enteromorpha, 49, 56, 64

Enteromorpha intestinalis, 58, 59

Enteromorpha prolifera, 58, 59

Entophysalis, 14, 32, 41, 73

Entophysalis deusta, 12, 59

Entophysalis lemaniae, 12, 14, 33, 41, 42, 73

Hpithemia, 12, 51, 74

Epithemia turgida, 12, 48, 74

Erythrotrichia carnea, 56, 58

Euastrum, 12, 34, 72

Euastrum oblongum, 12, 35, 42, 46, 72

Eudorina, 12, 20, 34, 45, 61, 64, 72

Eudorina elegans, 12, 35, 46, 72

Euglena, 8, 10, 11, 12, 20, 23, 30, 34, 39, 41, 44,
45, 51, 57, 58, 59, 64, 65, 73

Euglena acus, 59

Euglena adhaerens, 58

Euglena agilis, 12, 14, 38, 73

Euglena deses, 12, 38, 73

Euglena ehrenbergii, 12, 42, 73

Euglena gracilis, 12, 35, 38, 39, 46, 73

Euglena hiemalis, 58

Euglena mutabilis, 56, 58

Euglena orientalis, 51

Euglena oxyuris, 12, 38, 59, 73

(Euglena pisciformis) , 14

Euglena polymorpha, 12, 38, 73

Euglena rubra, 51

Euglena sanguinea, 12, 19, 51, 73

Huglena sanguinea var. furcata, 51

Euglena sociabilis, 59

Euglena spirogyra, 12, 42, 73

Euglena stellata, 58, 59

Euglena tatrica, 58

Euglena velata, 51

Euglena viridis, 12, 31, 38, 39, 58, 59, 73

Eunotia, 56, 59

Eunotia exigua, 58
Eunotia lunaris, 58
Eunotia trinacria, 58

Fragilaria, 12, 15, 20, 22, 28, 34, 45, 63, 64, 69
Fragilaria capucina, 12, 35, 46, 69
Fragilaria construens, 12, 19, 69

Fragilaria crotonensis, 12, 23, 29, 69
Fragilaria virescens, 58

Frustulia rhomboides var. saxonica, 59
Fucus, 56

Gelidium cartilagineum var. robustum, 5J

Glenodinium, 12, 20, 64, 72

Glenodinium palustre, 12, 19, 72

(Gloeocapsa ), 14, 20, 51

(Gloeocapsa conglomerata), 14

Gloeococcus, 12, 72

Gloeococcus schroeteri, 12, 42, 72

Gloeocystis, 12, 20, 64, 72

Gloeocystis gigas, 12, 48, 72

Gloeocystis.planctonica, 12, 19, 72

(Gloeothece), 14, 56

(Gloeothece linearis), 14

Gloeotrichia, 12, 20, 51, 68

Gloeotrichia echinulata, 12, 23, 51, 68

Gloeotrichia natans, 12, 44, 45, 46, 68

Golenkinia, 48, 64

Gomphonema, 10, 11, 12, 14, 30, 36, 47, 51, 59,
64, 72, 73

Gomphonema acuminatum, 59

Gomphonema geminatum, 12, 37, 48, 73

Gomphonema herculaneum, 58, 59

Gomphonema olivaceum, 12, 48, 73

Gomphonema’'parvulum, 12, 31, 38, 56, 58, 73

Gomphosphaeria, 10, 13, 14, 20, 26, 34, 45, 51,
52, 64, 72

Gomphosphaeria aponina, 18, 35, 46, 51, 72

Gomphosphaeria lacustris, 14, 51, 72

Gomphosphaeria lacustris, collinsii type, 13,
46, 72

Gomphosphaeria lacustris,
type, 18, 19, 27, 72

(Gomphosphaeria naegeliana), 14

Gomphosphaeria wichurae, 13, 14, 46, 72

Gonium, 11, 13, 20, 34, 45, 71

Gonium pectorale, 13, 35, 46, 71

Gonium sociale, 16

Gonyaulax, 53

Gonyaulax catenella, 51

Gonyaulax polyedra, 51

Gonyaulax tamarensis, 51

Gymnodinium, 53

Gymnodinium brevis, 51

Gymnodinium veneficum, 51, 53

Gyrosigma, 13, 74

Gyrosigma attenuatum, 13, 41, 46, 59, 74

kuetzingianum

Haematococcus, 10, 14, 64
Haematococcus lacustris, 9
Hantzschia, 13, 74

Hantzschia amphioxys, 13, 38, 57, 59, 74
Hantzschia elongata, 59
Hapalosiphon pumilus, 58
Hesperophycus harveyanus, 51
Hildenbrandia, 11, 13, 32, 71
Hildenbrandia rivularis, 13, 33, 42, 71
(Holopedium), 14

Hornellia marina, 51

Hyalotheca, 13, 69

Hyalotheca mucosa, 13, 46, 69

Hydrodictyon, 8, 10, 13, 18, 20, 26, 43, 64, 70
Hydrodictyon reticulatum, 9, 13, 19, 28, 27, 70
Hydrurus, 10

Hydrurus foetidus, 11

Kirchneriella, 18, 64, 71
Kirchneriella lunaris, 18, 46, 71

Lemanea, 10, 11, 13, 32, 41, 70
Lemanea annulata, 13, 33, 41, 42, 70
Lepocinclis, 13, 30, 73

Lepocinclis ovum, 18, 38, 56, 58, 73
Lepocinclis texta, 13, 31, 38, 73
Lyngbya, 11, 13, 15, 30, 36, 47, 53, 58, 68
Lyngbya aestuarii, 51, 58, 59
Lyngbya contorta, 51, 53

Lyngbya digueti, 13, 31, 38, 68
Lyngbya lagerheimii, 13, 37, 48, 68
Lyngbya majuscula, 51, 53
Lyngbya ocracea, 13, 48, 68
Lyngbya versicolor, 138, 46, 68

Macrocystis pyrifera, 51

Mallomonas, 13, 20, 26, 61, 64, 73
Mallomonas caudata, 138, 19, 27, 41, 42, 72
Mastigocladus laminosus, 58
Melosira, 5, 18, 15, 20, 28, 45, 64, 70
Melosira arenaria, 59

Melosira crenulata, 13, 46, 70
Melosira granulata, 13, 23, 29, 70
Melosira varians, 13, 28, 38, 56, 59, 70
Meridion, 13, 20, 32, 73

Meridion circulare, 13, 33, 42, 59, 73
(Merismopedia), 10, 14
(Merismopedia glauca), 9, 14
(Merismopedia: tennuissima), 14

' Merotrichia, 14, 61

Merotrichia ¢apitata, 16

Mesotaenium, 64

Micractinium, 138, 14, 34, 45, 71

Micractinium pusillum, 13, 35, 46, 71

Micrasterias, 13, 32, 72

Micrasterias truncata, 13, 33, 42, 72

Microcoleus, 11, 18, 32, 68

Microcoleus chthonoplastes, 59

Microcoleus paludosus, 16

Microcoleus subtorulosus, 18, 33, 42, 68

Microcrocis, 14

(Microcystis), 8, 10, 14, 19, 20, 48, 51, 53, 56,
63

(Microcystis aeruginosa ), 9, 14, 48, 51

(Microcystis flos-aquae), 51

(Microcystis toxica), 51

Microspora, 13, 36, 47, 58, 64, 70

Microspora amoena, 18, 37, 41, 48, 70

Microthamnion, 10

Microthamnion strictissimum, 11

Mougeotia, 13, 34, 45, 69

Mougeotia genuflexa, 13, 46, 69

Mougeotia sealaris, 13, 35, 46, 69

Mougeotia sphaerocarpa, 13, 23, 69

Navicula, 8, 11, 18, 14, 15, 22, 23, 28, 32, 39, 41,
44, 45, 57, 64, 75

Navicula anglica, 59

Navicula atomus, 59

Navicula cincta var. heufleri, 59
''Genus and Species Index

87

 

Navicula cryptocephala, 138, 38, 58, 59, 75

Navicula cuspidata, 59

Navicula exigua var. capitata, 18, 42, 75

Navicula gracilis, 18, 38, 42, 75

Navicula graciloides, 13, 23, 29, 75

Navicula gregaria, 59

Navicula lanceolata, 13, 28, 75

Navicula longirostris, 59

Navicula minima, 59

Navicula minuscula, 59

Navicula pygmaea, 59

Navicula radiosa, 13, 46, 58, 59, 75

Navicula salinarum, 59

Navicula subtilissima, 58, 59

Navicula viridis, 58

Navicula viridula, 58

Neidium, 64

Neidium bisulcatum, 58, 59

Nitella, 18, 20, 26, 47, 63, 64, 70

Nitella flexilis, 13, 48, 70

Nitella gracilis, 13, 19, 27, 70

Nitzschia, 18, 23, 30, 41, 57,-64, 74

Nitzschia acicularis, 13, 38, 74

Nitzschia apiculata, 59

Nitzschia epithemoides, 59

Nitzschia filiformfs, 58

Nitzschia frustulum, 59

Nitzschia ignorata, 59

Nitzschia linearis, 13, 42, 56, 58, 59, 74

Nitzschia palea, 13, 28, 31, 38, 39, 49, 57, 58, 59,
74

Nitzschia tryblionella var. debilis, 59

Nodularia, 18, 15, 34, 45, 68

Nodularia spumigena, 13, 35, 46, 51, 53, 54, 68

Nostoce, 20, 64, 68

Nostoc carneum, 138, 46, 68

Nostoe pruniforme, 18, 48, 68

Nostochopsis, 15

Nostochopsis lobatus, 16

Ochromonas, 56, 58

(Odontidium), 14

Oedogonium, 13, 36, 44, 47, 58, 69

Oedogonium boscii, 18, 48, 69

(Oedogonium crassiusculum var. idioandro-
sporum), 14

Oedogonium grande, 138, 48, 69

Oedogonium idioandrosporum, 13, 14, 46, 69

Oedogonium suecicum, 13, 37, 48, 69

Oocystis, 10, 11, 13, 34, 45, 64, 72

Oocystis borgei, 13, 35, 46, 72

Oocystis novae-semliae, 9

Oocystis parva, 49

Oodinium limneticum, 51

Oodinium ocellatum, 51, 54

Ophiocytium, 138, 74

Ophiocytium capitatum, 13, 46, 74

Oscillatoria, 8, 10, 18, 15, 20, 22, 23, 28, 30, 38,
. 89, 48, 50, 51, 58, 59, 64, 68, 69

Oscillatoria agardhii, 18, 46, 69

Oscillatoria amphibia, 13, 23, 69

Oscillatoria chalybea, 13, 23, 29, 38, 69

Oscillatoria chlorina, 13, 31, 38, 69

Oscillatoria curviceps, 138, 19, 69

Oscillatoria filiformis, 56, 58

Oscillatoria formosa, 13, 38, 69

Oscillatoria lauterbornii, 13, 31, 38, 69

Oscillatoria limosa, 13, 38, 39, 69

Oscillatoria ornata, 13, 23, 69

Oscillatoria princeps, 13, 23, 29, 38, 39, 69
Oscillatoria prolifica, 51

Oscillatoria pseudogeminata, 13, 23, 69
Oscillatoria putrida, 18, 31, 38, 69
Oscillatoria rubescens, 18, 28, 51, 69
Oscillatoria splendida, 18, 28, 29, 69
Oscillatoria tenuis, 13, 38, 39, 48, 69

Palmella, 18, 22, 28, 48, 51, 64, 72, 75

Palmella mucosa, 18, 23, 29, 48, 75

Pandorina, 10, 18, 20, 26, 45, 57, 58, 64, 72

Pandorina morum, 13, 19, 27, 38, 72

Pediastrum, 8, 18, 20, 34, 45, 57, 58, 64, 71

Pediastrum boryanum, 9, 13, 35, 46, 71

Pediastrum duplex, 13, 46, 57, 71

Pediastrum simplex, 59

Pediastrum tetras, 13, 19, 71

Pelvetia fastigiata, 51

Penium cucurbitinum, 58

Peridinium, 13, 19, 20, 26, 64, 72

Peridinium cinctum, 13, 19, 27, 72

Peridinium wisconsinense, 18, 23, 72

Phacotus, 18, 32, 73

Phacotus lenticularis, 18, 33, 42, 73

Phacus, 13, 23, 30, 34, 45, 58, 73

Phacus longicauda, 18, 42, 73

Phacus pleuronectes, 13, 35, 46, 73

Phacus pyrum, 13, 31, 38, 73

Phormidium, 10, 13, 15, 30, 36, 39, 41, 47, 51,
64, 68, 69

Phormidium autumnale, 138, 31, 38, 69

Phormidium bijahensis, 58

Phormidium geysericola, 58

Phormidium inundatum, 13, 42, 69

Phormidium laminosum, 58

Phormidium retzii, 18, 46, 48, 69

Phormidium tenue, 59

Phormidium uncinatum, 13, 37, 38, 39, 48, 49,
69

Phytoconis, 10, 13, 14, 36, 39, 47, 51, 72, 75

Phytoconis botryoides, 9, 18, 14, 37, 48, 75

Pinnularia, 13, 14, 32, 41, 58, 58, 59, 75

Pinnularia borealis, 58

Pinnularia microstauron, 59

Pinnularia nobilis, 13, 33, 42, 75

Pinnularia subeapitata, 13, 42, 75

Pinnularia subeapitata var. hilseana, 59

Pithophora, 13, 47, 64, 70

Pithophora oedogonia, 18, 48, 70

Plectonema, 13, 64, 70

Plectonema tomasiniana, 18, 46, 70

Pleodorina, 14

Pleodorina illinoisensis, 16

Pleurosigma, 20

(Polycystis), 14, 19

(Polycystis aeruginosa), 14

Porphyra leucosticta, 56, 58

(Protococcus), 10, 14, 39, 47, 51

(Protococcus viridis), 9, 14

Prymnesium parvum, 51, 53

Pyrobotrys, 13, 14, 30, 72

Pyrobotrys gracilis, 13, 38,72 .

Pyrobotrys stellata, 13, 31, 38, 72

Pyrodinium phoneus, 51

Rhizoclonium, 18, 32, 41, 49, 70

Rhizoclonium hieroglyphicum, 13, 33, 42, 48,
70

Rhizosolenia, 13, 45, 74

Rhizosolenia gracilis, 18, 46, 74
Rhodomonas, 13, 32, 61, 73
Rhodomonas lacustris, 13, 33, 42, 73
Rhoicosphenia, 13, 73
Rhoicosphenia curvata, 18, 48, 73
Rhopalodia, 18, 74

Rhopalodia gibba, 13, 46, 74
Rivularia, 13, 20, 22, 28, 64, 68
Rivularia dura, 13, 23, 29, 68
Rivularia haematites, 13, 19, 68

Scenedesmus, 11, 13, 14, 20, 34, 48, 45, 51, 58,
64, 69, 71

Scenedesmus abundans, 13, 19, 71

Scenedesmus bijuda, 13, 46, 49, 71

Scenedesmus bijugatus, 59

Scenedesmus dimorphus, 13, 46, 71

Scenedesmus obliquus, 57, 58

Scenedesmus quadricauda, 13, 16, 35, 38, 46, 71

Schizomeris, 13, 47, 71

Schizomeris leibleinii, 13, 48, 71

Schroederia, 13, 73

Schroederia setigera, 13, 46, 73

Scytonema, 13, 68

Scytonema ocellatum, 58

Scytonema tolypothricoides, 13, 46, 68

Selenastrum, 18, 71

Selenastrum gracile, 13, 46, 71

Skeletonema, 56

(Sphaerella), 10, 14

(Sphaerella lacustris), 9

Sphaerocystis, 11, 13, 34, 45, 72

Sphaerocystis schroeteri, 13, 35, 46, 72

Spirogyra, 8, 10, 18, 20, 22, 28, 30, 44, 51, 63,
64, 69

Spirogyra communis, 13, 31, 38, 69

Spirogyra crassa, 55, 58

Spirogyra decimena, 55, 58

Spirogyra ellipsospora, 8, 9

Spirogyra fluviatilis, 13, 46, 69

Spirogyra majuscula, 13, 19, 69

Spirogyra porticalis, 13, 23, 29, 69

Spirogyra varians, 8, 9, 13, 46, 69

Spirulina, 13, 75

(Spirulina jenneri), 14

Spirulina nordstedtii, 13, 46, 75

Spirulina subsalsa, 58, 59

Spondylomorum, 13, 57, 58, 72

Spondylomorum quaternarium, 18, 38, 72

Staurastrum, 13, 20, 26, 32, 64, 72

Staurastrum’ paradoxum, 13, 19, 27, 72

Staurastrum polymorphum, 13, 46, 72

Staurastrum punctulatum, 13, 33, 42, 72

Stauroneis, 13, 34, 45, 75

Stauroneis anceps, 58

Stauroneis phoenicenteron, 13, 35, 46, 59, 75

Stenopterobia intermedia, 59

Stephanodiscus, 13, 20, 34, 64, 74

Stephanodiscus astraea, 45

Stephanodiscus binderanus, 13, 23, 74

Stephanodiscus hantzschii, 13, 23, 35, 45, 46,
74

Stephanodiscus niagarae, 13, 19, 74

Stephanoptera gracilis, 59

Stichococcus, 18, 70

Stichococcus bacillaris, 138, 38, 70

Stigeoclonium, 10, 18, 15, 30, 36, 49, 57, 64, 70

Stigeoclonium lubricum, 138, 37, 48, 70

Stigeoclonium nanum, 48
''88

ALGAE IN WATER SUPPLIES

 

Stigeoclonium stagnatile, 13, 46, 70

Stigeoclonium tenue, 13, 31, 38, 39, 58, 59, 70

Stigonema, 13, 47, 71

Stigonema hormoides, 48

Stigonema minutum, 13, 48, 71

Surirella, 13, 32, 41, 74

Surirella delicatissima, 59

Surirella linearis, 59

Surirella molleriana, 59

Surirella ovata, 13, 38, 58, 74

Surirella ovata var. salina, 58, 59

Surirella splendida, 13, 33, 42, 74

Symploca, 10, 64

Symploca erecta, 58

Symploca muralis, 9

(Synechococcus) , 14, 58

Synedra, 5, 18, 14, 20, 22, 23, 26, 28, 39, 44, 45,
51, 52, 64, 75

Synedra acus, 13 23 29, 59, 75

Synedra acus var. angustissima, 18, 42, 75

Synedra acus var. radians, 18, 14, 28, 75

Synedra affinis, 59

Synedra capitata, 18, 46, 75

(Synedra delicatissima), 14, 23

Synedra pulchella, 13, 23, 58, 59, 75

Synedra ulna, 19, 27, 58, 59, 71, 75

Synura, 5, 8, 10, 14, 19, 20, 26, 44, 61 63, 64, 71
Synura uvella, 14, 19, 27, 58, 71

Tabellaria, 5, 14, 15, 20, 22, 26, 28, 45, 63, 64, 74
Tabellaria fenestrata, 14, 19, 23, 27, 74
Tabellaria flocculosa, 14, 28, 29, 58, 74
Tetraedron, 10, 14, 30, 64, 72

Tetraedron muticum, 14, 31, 38, 72

Tetraspora, 10, 14, 36, 47, 48, 51, 57, 59, 71, 72
Tetraspora gelatinosa, 14, 37, 48, 71
Tolypothrix, 18, 15, 36, 47, 68

Tolypothrix tenuis, 14, 37, 48, 68
Trachelomonas, 11, 18, 22, 23, 28, 58, 59, 73
Trachelomonas crebea, 14, 23, 29, 73
Trachelomonas hispida, 56, 59

Trentepohlia aurea, 16

Tribonema, 13, 26, 22, 28, 48, 45, 58, 64, 70
Tribonema bombycinum, 14, 23, 29, 70
Tribonema minus, 14, 46, 70

Trichodesmium, 59

Trichodesmium erythraeum, 51

Ulothrix, 13, 20, 32, 36, 41, 47, 58, 59, 64, 70
Ulothrix aequalis, 14, 33, 42, 70

Ulothrix tenerrima, 14, 46, 70

Ulothrix tenuissima, 49

Ulothrix variabilis, 14, 23, 70

Ulothrix zonata, 14, 37, 39, 41, 48, 56, 58, 70
Ulva, 8

Ulva lactuca, 56, 58

Ulva latissima, 56, 58 .
Uroglena, 20

Uroglenopsis, 13, 19, 20, 26, 61, 63, 64, 72
Uroglenopsis americana, 14, 19, 27, 72

Vanheurckia rhomboides var. crassenervia,
58

Vaucheria, 8, 10, 13, 36, 47, 71

Vaucheria arechavaletae, 16

Vaucheria geminata, 14, 42, 47, 48, 71

Vaucheria sessilis, 14, 37, 47, 48, 71

Vaucheria terrestris, 46, 71

Volvox, 10, 13, 20, 26, 58, 64, 72

Volvox aureus, 14, 19, 27, 72

Xanthidium antilopaeum, 58

Zygnema, 13, 34, 44, 45, 64, 69
Zygnema insigne, 14, 28, 69
Zygnema normani, 16
Zygnema pectinatum, 14, 46, 69
Zygnema sterile, 14, 35, 46, 69

U.S. GOVERNMENT PRINTING OFFICE: 1959 O—-496792
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''Public Health Service Publication No. 657
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€029374b480
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