(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "An annotated key to the identification of commonly occurring and dominant genera of algae observed in the phytoplankton of the United States"

nnotate 



Commonly Occurrir 
of Algae Observed in 
of the United States 



tihcation oi 
nt Gene 








t p.NOG» 



a 



r v it % 




^° 



MBL/WHOI 

Library 






7fa£s*jl, 7Js*&p* 




An Annotated Key to the Identification of 
Commonly Occurring and Dominant Genera 
of Algae Observed in the Phytoplankton 
of the United States 



• 6 



By PHILLIP E. GREESON 



GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2079 



== n- 



CD- 



■ o 

! "i 

: cd 

I ° 
t-=\ 

CD 

m 





UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1982 



UNITED STATES DEPARTMENT OF THE INTERIOR 
JAMES G. WATT, Secretary 



GEOLOGICAL SURVEY 
Dallas L. Peck, Director 



Library of Congress catalog-card No. 81-600168 



For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 



CONTENTS 



Page 

Abstract 1 

Introduction 1 

Acknowledgment 3 

Taxonomic key to the identification of commonly occurring and dominant genera 

of algae observed in the phytoplankton of the United States 9 

Descriptions of the genera 14 

Chlorophyta 14 

Actinastrum 14 

Ankistrodesmus 16 

Chlamydomonas 18 

Chodatella 20 

Coelastrum 22 

Cosmarium 24 

Crucigenia 26 

Dictyosphaerium 28 

Golenkinia 30 

Kirchneriella 32 

Micractinium 34 

Oocystis 36 

Pandorina 38 

Pediastrum 40 

Scenedesmus 42 

Schroederia 44 

Selenastrum 46 

Sphaerocystis 48 

Tetraedron 50 

Tetrastrum 52 

Euglenophyta 54 

Euglena 54 

Trachelomonas 56 

Chrysophyta 58 

Achnanthes 58 

Amphora 60 

Asterionella 62 

Cocconeis 64 

Cyclotella 66 

Cymbella 68 

Diatoma 70 

Dinobryon 72 

Epithemia 74 

Eunotia 76 

Fragilaria 78 

Gomphonema 80 

Gyrosigma 82 

in 



IV CONTENTS 

Page 

Descriptions of the genera- Continued 

Chrysophyta - Continued 

Melosira 84 

Navicula 86 

Nitzschia 88 

Pinnularia 90 

Rhoicosphenia 92 

Stephanodiscus 94 

Surirella 96 

Synedra 98 

Tabellaria 100 

Pyrrophyta 102 

Glenodinium 102 

Peridinium 104 

Cryptophyta 106 

Chroomonas 106 

Cryptomonas 108 

Cyanophyta 110 

Agmenellum 110 

Anabaena 112 

Anacystis 114 

Aphanizomenon 116 

Cylindrospermum . 118 

Gomphosphaeria 120 

Lyngbya 122 

Oscillatoria 124 

Phormidum 126 

Raphidiopsis 128 

Glossary 130 

Selected references 133 



ILLUSTRATIONS 



Figures 1-4. Drawings of: 

1. Actinastrum 15 

2. Ankistrodesmus 17 

3. Chlamydomonas 19 

4. Chodatella 21 

5. Photomicrograph of Coelastrum 23 

6, 7. Drawings of: 

6. Cosmarium 25 

7. Crucigenia 27 

8. Photomicrograph of Dictyosphaerium 29 

9, 10. Drawings of: 

9. Golenkinia 31 

10. Kirchneriella 33 

11,12. Photomicrographs of : 

11. Micractinium 35 

12. Oocystis 37 

13. Drawing of Pandorina 39 



CONTENTS V 

Page 

Figures 14, 15. Photomicrographs of: 

14. Pediastrum 41 

15. Scenedesmus 43 

16-20. Drawings of: 

16. Schroederia 45 

17. Selenastrum 47 

18. Sphaerocystis 49 

19. Tetraedron 51 

20. Tetrastrum 53 

21-25. Photomicrographs of: 

21. Euglena 55 

22. Trachelomonas 57 

23. Achnanthes 59 

24. Amphora 61 

25. Asterionella 63 

26, 27. Scanning electronmicrographs of: 

26. Cocconeis 65 

27. Cyclotella 67 

28-30. Photomicrographs of: 

28. Cymbella 69 

29. Diatoma 71 

30. Dinobryon 73 

31. Scanning electronmicrograph of Epithemia 75 

32. Drawing of Eunotia 77 

33-35. Photomicrographs of: 

33. Fragilaria 79 

34. Gomphonema 81 

35. Gyrosigma 83 

36. Scanning electronmicrograph of Melosira 85 

37-40. Photomicrographs of: 

37. Navicula 87 

38. Nitzschia 89 

39. Pinnularia 91 

40. Rhoicosphenia 93 

41. Scanning electronmicrograph of Stephanodiscus 95 

42. Photomicrograph of Surirella 97 

43. Drawing of Synedra 99 

44, 45. Photomicrographs of: 

44. Tabellaria 101 

45. Glenodinium 103 

46-48. Drawings of: 

46. Peridinium 105 

47. Chroomonas 107 

48. Cryptomonas 109 

49-52. Photomicrographs of: 

49. Agmenellum 111 

50. Anabaena 113 

51. Anacystis 115 

52. Aphanizomenon 117 

53, 54. Drawings of: 

53. Cylindrospermum 119 

54. Gomphosphaeria 121 



VI CONTENTS 

Page 

Figures 55, 56. Photomicrographs of: 

55. Lyngbya 123 

56. Oscillatoria 125 

57, 58. Drawings of: 

57. Phormidium 127 

58. Raphidiopsis 129 



TABLES 



Page 

Table 1. List of algal genera observed in the phytoplankton of the United 

States 4 

2. Commonly occurring genera of algae observed in the phytoplankton of 

the United States 6 

3. Dominant genera of algae observed in the phytoplankton of the United 

States 7 

4. Taxonomic groupings of commonly occurring and dominant genera of 

algae of the United States 8 



A Note on the Illustrations in this Book: 

The drawings of alga genera shown in figures 
1, 2, 3, 4, 6, 7, 9, 10, 13, 16, 17, 18, 19. 
20, 32, 43, 46, 47, 48, 53, 54, 57, 58 were 
redrawn from originals in Smith, 1950, pub- 
lished by the McGraw-Hill Book Company and 
are shown here under license from McGraw-Hill. 
The scanning electron-micrographs were made 
by Bruce W. Lium and to*. Thomas Shoaf III, 
U.S. Geological Survey. The photomicrographs 
were made by the author. 



AN ANNOTATED KEY TO THE 

IDENTIFICATION OF COMMONLY 

OCCURRING AND DOMINANT GENERA OF 

ALGAE OBSERVED IN THE 

PHYTOPLANKTON OF THE UNITED STATES 



By Phillip E. Greeson 



ABSTRACT 



In early 1979, a retrieval was made for all phytoplankton data contained in the com- 
puterized data file of the U. S. Geological Survey. The retrieval revealed the analytical 
results of 17,959 samples collected and processed between October 1973 and October 
1978. Of the approximately 500 genera of freshwater algae reported in the United States, 
the U.S. Geological Survey observed 321 genera in the phytoplankton. Fifty-two genera 
were considered to be commonly occurring and 42 genera were considered to be com- 
munity dominants. The report lists, describes, and provides a detailed taxonomic key to 
the identification of 58 genera of algae considered either commonly occurring or domi- 
nant. Also included is a summary of environmental conditions under which each algal 
genus was observed, as well as a glossary and an extensive list of selected references. 

INTRODUCTION 

Taxonomy is the science concerned with the orderly arrangement of 
organisms in some scheme of likenesses and differences among the 
various individuals. The present taxonomic system was developed 
mostly during the 18th and 19th centuries. During the mid-1800's, tax- 
onomy played an additional and equally important role, that being the 
basic tool in the analysis of evolutionary relationships among 
organisms. This is commonly called the science of systematics. It was 
in the early- 1900's when investigators began to realize that organisms 
not only had certain inherent relationships but also were sensitive to 
changes in the environment. 

Since the beginning of the 20th century, numerous publications have 
discussed algae as indicators of environmental conditions. Perhaps the 
most important contribution on ecological indicators was by Kolkwitz 
and Marrson (1908), who introduced the concept of indicator species. 
This resulted in the "saprobian" system for classifying organisms in 
organically polluted rivers. 

After the paper by Kolkwitz and Marrson, many similar papers were 
published; all discussed indicator species. The importance of biological 
indicators as an index of pollution was described by Forbes (1913), 



2 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

when he stated that "* * * it is quite possible to arrange plants and 
animals of a stream in the order of their preference for, or tolerance of, 
organic impurities, in such a way that a graded list of them may serve 
as an index to grades of contamination." 

W. C. Purdy (1922), a plankton specialist with the U.S. Public Health 
Service, clearly recognized the value of biological indicators when he 
concluded, "If it be true that the biological life of a stream is distinctly 
and profoundly affected by the numerous factors which form the en- 
vironment, it follows that the organisms in a stream constitute in a 
general way a reflection of the prevailing environmental conditions of 
the stream." 

Thienemann (1939) was the first to demonstrate that groups of 
species were characteristic of a given type of environment. Community 
structure as an indicator of environmental conditions thereby became a 
firmly established concept. Fjerdingstad (1950) was the first to con- 
sider algal community-dominant species, associate species, and ac- 
cidental species. Perhaps the most well known paper considering com- 
munity structure as an indicator was by Patrick (1949). In it, she coined 
the terms "healthy," "semihealthy," "polluted," and "very polluted" to 
describe the variability one might expect in the organisms and yet in- 
dicate the degree of degradation that had taken place in a stream. 

Subsequent to Patrick's paper, the emphasis changed from studies 
that were purely qualitative in nature to quantitative expressions of 
community structures, associations, and diversities. 

With the realization of the importance of biota as indicators and of 
the need to characterize the quality of water, including the biological 
quality, in major waterways of the United States, the U.S. Public 
Health Service initiated the National Water Quality Network in 1957. 
Samples for determining the physical, chemical, and biological quality 
at 128 stations were collected through 1962 (Williams, 1962, 1964, 
1966). The network continued until the late 1960's as the Water Pollu- 
tion Surveillance System under the purview of the Federal Water 
Pollution Control Administration (now the U.S. Environmental Protec- 
tion Agency) (Weber, 1966). 

The changing emphasis toward the preservation of environmental 
quality during the 1960's awakened the need for a long-term data base 
with which changes in water quality could be determined. As a result, 
the U.S. Geological Survey initiated the National Stream-Quality Ac- 
counting Network (NASQAN) in 1973. NASQAN is a series of stations 
at which systematic and continuing measurements are made to deter- 
mine the quality of the Nation's streams. Design of the network 
specifies measurement of a broad range of water-quality 
characteristics, including biological characteristics, which were 
selected to meet many of the information requests of groups involved 



ACKNOWLEDGMENT 3 

in planning and management on a national or regional scale. The 
primary objectives of NASQAN are (1) to account for the quantity and 
quality of surface water moving within and from the United States, (2) 
to depict areal variability, (3) to detect changes in stream quality, and 
(4) to provide the groundwork for future assessments of changes in 
stream quality (Ficke and Hawkinson, 1975). 

As part of NASQAN, phytoplankton samples are obtained seven 
times a year from about 540 stations. The samples are processed for 
generic identification and enumeration by the U.S. Geological Survey's 
Central Water-Quality Laboratory in Atlanta, Ga., in accord with the 
methods of Greeson and others (1977) and Greeson (1979). All data are 
stored in the computerized data files (WATSTORE and BIOTAB) of 
the U.S. Geological Survey. 

In early 1979, a retrieval was made for all phytoplankton data con- 
tained in BIOTAB. The data included those collected as part of 
NASQAN, as well as those data collected as part of other activities of 
the U.S. Geological Survey. About 80 percent of the file represented 
NASQAN data. During the 5-year period between October 1973 and 
October 1978, a total of 17,959 phytoplankton samples were processed. 
Using the almost 18,000 samples as a basis, this publication lists, 
describes, and provides a detailed taxonomic key for the identification 
of commonly occurring and dominant genera of algae observed in the 
phytoplankton of the United States. A summary of environmental con- 
ditions under which each algal genus was observed is included. Also in- 
cluded is a glossary and an extensive list of selected references. 

Of the approximately 500 genera of freshwater algae reported in the 
United States (Greeson, 1970), the U.S. Geological Survey has ob- 
served 321 genera in the phytoplankton (table 1). Fifty-two genera 
reported in 5 percent or more of the samples were considered to be 
commonly occurring (table 2). Forty-two genera were dominant in 1 
percent or more of the samples (table 3). A dominant genus was con- 
sidered to be one that comprises 15 percent or more of the total cell 
count of a sample. Table 4 lists in alphabetical order by taxonomic 
groupings the 58 genera of algae that were either commonly occurring 
or dominant in the samples. 

ACKNOWLEDGMENT 

The author acknowledges with sincerest appreciation the many per- 
sons of the U.S. Geological Survey who made this publication possible. 
A special thanks is extended to James M. Bergmann, developer of 
BIOTAB, for his assistance with data retrievals; to the field personnel 
who performed their duties under extremely demanding conditions; 
and to the supervisors and analysts in the U.S. Geological Survey's 
laboratory in Atlanta for their perseverance in spite of an overwhelm- 
ing number of samples. 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Table 1. -List of algal genera observed in the phytoplankton of the United States 

CHLOROPHYTA (Green algae) 



Acanthosphaera 

Actidesmium 

Actinastrum 

A nkis trodesmus 

Ankyra 

Arthrodesmus 

Asterococcus 

Bambusina 

Binuclearia 

Bohlinia 

Botryococcus 

Brachiomonas 

Carteria 

Cephalmonas 

Cerasterias 

Chaetophora 

Characium 

Chlamydomonas 

Chloretla 

Chlorochytrium 

Chlorococcum 

Chlorogonium 

Chloromonas 

Chlorosarcina 

Chodatella 

Cladophora 

Closteridium 

Closteriopsis 

Closterium 

Coccomonas 

Coelastrum 

Coleochaete 

Coronastrum 

Cosmarium 

Cosmocladium 

Crucigenia 

Cylindrocapsa 

Cylindrocystis 

Dactylococcus 

Dactylothece 

Desmatractum 

Desmidium 

Dicho tomococcus 

Dictyosphaerium 

Dimorphococcus 

Dispora 

Dunaliella 

Dysmorphococcus 

Echinosphaerella 

Elakatothrix 

Eremosphaera 

Errerella 

Euastropsis 



Euastrum 
Eudorina 
Eutetramorns 

Franceia 
Fridaea 

Geminella 

Gloeoactinium 

Gloeocystis 

Golenkinia 

Golenkiniopsis 

Gonatozygon 

Gonium 

Haematococcus 

Heteromastix 

Hormidium 

Hormotila 

Hyalotheca 

Hydrodictyon 

Kirchneriella 

Lobomonas 

Mesostigma 

Mesotaenium 

Micractinium 

Micrasterias 

Microspora 

Mougeotia 

Mougeotiopsis 

Nannochloris 

Nephrocytium 

Netrium 

Oedogonium 
Onychonema 
Oocystis 
Ourococcus 

Pachycladon 

Palmella 

Palmellococcus 

Palmodictyon 

Pandorina 

Pediastrum 

Penium 

Phacotus 

Phyllobium 

Phymatodocis 

Planktosphaeria 

Platydorina 

Platymonas 

Pleodorina 



Pleurotaenium 

Polyedriopsis 

Polytoma 

Protococcus 

Protosiphon 

Pteromonas 

Pyramimonas 

Pyrobotrys 

Quadricoccus 
Quadrigula 

Radiococcus 

Raphidonema 

Rhizoclonium 

Rhodochytrium 

Roya 

Scenedesmus 

Schizochlamys 

Schroederia 

Selenastrum 

Sorastrum 

Spermatozoopsis 

Sphaerellopsis 

Sphaerocystis 

Sphaerozosma 

Spirogyra 

Spondylomorum 

Spondylosium 

Staurastrum 

Stichococcus 

Stigeoclonium 

Stylosphaeridium 

Tetmemorus 

Tetradesrmis 

Tetraedron 

Tetrallantos 

Tetraspora 

Tetrastrum 

Thoracomonas 

Trebouxia 

Treubaria 

Trochiscia 

Ulothrix 
Uronema 

Volvox 

Westella 
Wislouchiella 

Xanthidium 

Zygnema 
Zygnemopsis 



EUGLENOPHYTA (Euglenoids) 



Astasia 

Calcycimonas 

Colacium 

Cryptoglena 

Distigma 



Euglena 

Euglenopsis 

Eutreptia 

Lepocinclis 

Menoidium 



Phacus 
Protochrysis 
Strombomonas 
Trachelomonas 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Table l.-List of algal genera observed in the phytoplankton of the United 

States - Continued 

CHRYSOPHYTA 

Chrysophytes 



Amphichrysis 

Botrydiopsis 
Bumilleriopsis 

Centritractus 

Characiopsis 

Chlorallanthus 

Chlorellidiopsis 

Chlorobotrys 

Chlorocloster 

Chromulina 

Chrysamoeba 

Chrysochroviulina 

Chrysococcus 

Chrysosphaerella 

Chrysoxys 

Cyclonexis 



Diachros 

Diceras 

Dinobryon 

Epipyxis 
Gloeochloris 

Harpochytrium 
Hydrurus 

Kephyrion 

Mallomonas 
Mischococcus 

Ochromonas 

Olisthodiscus 

Ophiocytium 



Perone 

Peromelia 

Pseudokephyrion 

Rhizochrysis 

Stipitococcus 
Synura 

Tribonema 

Uroglena 
Uroglenopsis 



CHRYSOPHYTA 

Diatoms 



Achnanthes 

Actinella 

Actinocyclus 

Amphicampa 

Amphipleura 

Amphora 

Anomoeoneis 

Asterionella 

Attheya 

Auliscus 

Biddulphia 

Caloneis 

Campylodiscus 

Cerataulina 

Chaetoceros 

Cocconeis 

Coscinodiscus 

Cyclotella 

Cylindrotheca 

Cymbella 

Denticula 
Diatoma 
Diatomella 
Diploneis 



Entomoneis 

Epithemia 

Eunotia 

Fragilaria 
Frustulia 

Gomphoneis 
Gomphonema 
Guinardia 
Gyrosigma 

Hannaea 
Hantzschia 
Hemiaulus 
Hyalodiscus 

Licmophora 

Mastogloia 
Melosira 

Meridion 

Navicula 
Neidium 
Nitzschia 



Opephora 

Pinnularia 

Plagiotropsis 

Pleurosigma 

Rhabdonema 
Rhizosolenia 
Rhoicosphenia 
Rhapalodia 

Scoliopleura 

Skeletonema 

Stauroneis 

Stephanodiscus 

Stephanopyxis 

Streptotheca 

Surirella 

Synedra 

Tabellaria 

Terpsinoe 

Tetracyclus 

Thalassiosira 



PHYRROPHYTA (Dinoflagellates) 



Amphidinium 
Ceratium 
Dinophysis 
Exuviaella 



Glenodinium 
Gonyaulax 
Gymnodinium 
Gyrodinium 



Hemidinium 

Massartia 

Oxyphysis 

Peridinium 

Prorocentrum 



CRYPTOPHYTA (Cryptomonads) 



Chilomonas 
Chroomonas 



Cryptomonas 
Cyanomonas 



Rhodomonas 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Table l.-List of algal genera observed in the phytoplankton of the United 

States - Continued 

CYANOPHYTA (Blue-green algae) 



Agmenellum 

Anabaena 

Anabaenopsis 

Anacystis 

Aphanizomenon 

Arthrospira 

Borzia 

Calothrix 

Coccochloris 

Cylindrospermum 

Dactylococcopsis 

Entophysalis 



Gloeocapsa 

Gloeotrichia 

Gomphosphaeria 

Hydrocoleum 

Isocystis 

Johannesbap tis tia 

Kyrkia 

Lyngbya 

Microcoleus 
Nodularia 



Nostoc 

Oscillatoria 

Phormidium 

Plectonema 

Porphyrosiphon 

Raphidiopsis 
Rivularia 

Schizothrix 

Spirulina 

Symploca 

Tetrapedia 
Trichodesmium 



RHODOPHYTA (Red algae) 



Audouinella Bangia 

Table 2. -Commonly occurring genera of algae observed in the phytoplankton of the 

United States 



Genus 

Nitzschia 

Navicula 

Cyclotella 

Scenedesmus 

Ankistrodesmus 

Melosira 

Synedra 

Gomphonema 

Anacystis 

Oscillatoria 

Achnanthes 

Cymbella 

Chlamydomonas 

Cocconeis 

Diatoma 

Trachelomonas 

Fragilaria 

Surirella 

Euglena 

Kirchneriella 

Asterionella 

Oocystis 

Dictyosphaerium 

Crucigenia 

Cryptomonas 

Anabaena 

Lyngbya 

Rhoicosphenia 

Agmenellum 

Tetraedron 



Number of 
occurrence 1 



Percent 



13,480 


75 


12,374 


69 


11,161 


62 


8,580 


48 


8,161 


45 


7,446 


41 


7,001 


39 


6,519 


36 


5,852 


33 


5,556 


31 


4,962 


28 


4,938 


27 


4,649 


26 


4,182 


23 


3,906 


22 


3,625 


20 


3,255 


18 


2,984 


17 


2,763 


15 


2,580 


14 


2,538 


14 


2,518 


14 


2,446 


14 


2,289 


13 


2,226 


12 


2,164 


12 


2,080 


12 


1,952 


11 


1,849 


10 


1,793 


10 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Table 2. -Commonly occurring genera of algae observed in the phytoplankton of the 

United States - Continued 

._, Number of D „.„ .. 

Genus occurrence' Percent 

Actinastrum 

Pediastrum 

Micractinium 

Schroederia 

Amphora 

Tetrastrum 

Gyrosigma 

Epithemia 

Coelastrum 

Dinobryon 

Pinnularia 

Selenastrum 

Aphanizomenon 

Stephanodiscus 

Chroomonas 

Glenodinium 

Peridinium 

Eunotia 

Chodatella 

Golenkinia 

Cosmarium 



1,672 


9 


1,611 


9 


1,499 


8 


1,413 


8 


1,409 


8 


1,315 


7 


1,288 


7 


1,261 


7 


1,250 


7 


1,247 


7 


1,230 


7 


1,222 


7 


1,127 


6 


1,092 


6 


1,027 


6 


962 


5 


950 


5 


879 


5 


852 


5 


847 


5 


817 


5 



Based on 17,959 samples. 



Table 3. -Dominant genera 1 of algae observed in the phytoplankton of the United States 



Genus Number of p t 

dominances 2 



Nitzschia 

Oscillatoria . 

Cyclotella 

Navicula 

Anacystis 

Melosira 

Scenedesmus 



Lyngbya 

Synedra 

Achnanthes 

Agmenellum 

Anabaena 

Gomphonema 

Fragilaria 

Asterionella 

A nkistrodesmus . 
Aphanizomenon . 

Diatoma 

Chlamydomonas . 
Dictyosphaerium 

Cymbella 

Cocconeis 

Crucigenia 

Gomphosphaeria . 



3,530 


20 


3,402 


19 


3,362 


19 


3,361 


19 


2,696 


15 


2,388 


13 


1,831 


10 


1,091 


6 


734 


4 


732 


4 


701 


4 


691 


4 


685 


4 


679 


4 


543 


3 


536 


3 


520 


3 


429 


2 


375 


2 


372 


2 


327 


2 


306 


2 


280 


2 


266 


3 2 



8 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Table 3. -Dominant genera 1 of algae observed in the phytoplankton of the United 

States - Continued 



Genus 



Number of 
dominances 2 



Percent 



Trachelomonas 

Coelastrum 

Actinastrum 

Pediastrum 

Micractinium 

Cryptomonas 

Oocystis 

Dinobryon 

Sphaerocystis 

Surirella 

Cylindrospermum 

Chroomonas 

Pandorina 

Euglena 

Phormidium 

Eunotia 

Raphidiopsis 

Kirchneriella 

' Comprising 15 percent or more of sample. 

2 Based on 17,959 samples 

3 Not a commonly occurring genus (see tabli 2) 



210 


1 


209 


1 


179 


1 


171 


1 


170 


<1 


145 


<1 


145 


<1 


144 


<1 


144 


3 <1 


126 


<1 


124 


3 <1 


120 


<1 


103 


3 <1 


97 


<1 


92 


3 <1 


91 


<1 


91 


3 <1 


79 


<1 



Table 4.-Taxonomic groupings of commonly occurring and dominant genera of algae of 

the United States 



CHLOROPHYTA (Green algae) 



Actinastrum 

Ankistrodesmus 

Chlamydomonas 

Chodatella 

Coelastrum 

Cosmarium 

Crucigenia 



Dictyosphaeriurn 

Golenkinia 

Kirchneriella 

Micractinium 

Oocystis 

Pandorina 

Pediastrum 



Scenedesmus 

Schroederia 

Selenastrum 

Sphaerocystis 

Tetraedron 

Tetrastrum 



EUGLENOPHYTA (Euglenoids) 



Euglena 



Trachelomonas 



CHRYSOPHYTA (Chrysophytes and diatoms) 



A chnanthes 

Amphora 

Asterionella 

Cocconeis 

Cyclotella 

Cymbella 

Diatoma 

Dinobryon 



Epithemia 

Eunotia 

Fragilaria 

Gomphonema 

Gyrosigma 

Melosira 

Navicula 



Nitzschia 

Pinnularia 

Rhoicosphenia 

Stephanodiscus 

Surirella 

Synedra 

Tabellaria 



PYRROPHYTA (Dinoflagellates) 



Glenodinium 



Peridinium 



CRYPTOPHYTA (Cryptomonads) 



Chroomonas 



Cryptomonas 



CYANOPHYTA (Blue-green algae) 



Agmenellum 

Anabaena 

Anacystis 

A phanizomenon 



Cylindrospermum 

Gomphosphaeria 

Lyngbya 



Oscillatoria 

Phormidium 

Raphidiopsis 



TAXONOMIC KEY 9 

TAXONOMIC KEY TO THE IDENTIFICATION OF COMMONLY 

OCCURRING AND DOMINANT GENERA OF ALGAE 

OBSERVED IN THE PHYTOPLANKTON OF THE 

UNITED STATES 

[The following key consists of couplets of characteristics. One must decide which state- 
ment of the couplet most accurately describes the specimen. Having made a selection, 
proceed to the couplet indicated by the number to the right. Continue through the key un- 
til a genus is indicated. The key is constructed for the 58 genera described in this report. 
The identification of other genera requires the use of a more comprehensive key.] 

1A Plant pigments contained in chromatophores 

or chloroplasts ^q 

IB Plant pigments not contained in chromato- 
phores or chloroplasts, but diffused 

through protoplast 2 

2 A Plants filamentous; cells arranged 

in trichomes 4 

2B Plants colonial, not filamentous 3 

3A Cells in regular rows, generally in multiples 

of four; colony one cell in thickness Agmenellum 

3B Cells somewhat evenly arranged toward 
periphery of spherical colony; barely 
visible gelatinous strands radiate from 

center of colony to cells Gomphosphaeria 

3C Colony asymmetrical; cells very dense and 

unevenly distributed Anacystis 

4A Filaments straight or slightly 

flexed 6 

4B Filaments curved, twisted, or 

spiraled 5 

5A Heterocysts and akinetes present Anabaena 

5B Heterocysts absent Raphidiopsis 

6A Heterocysts present 9 

6B Heterocysts absent 7 

7A Filaments without a sheath; cells discoid Oscillatoria 

7B Filaments with distinct sheath 8 

8A Trichomes tangled; sheaths con- 
fluent Phormidium 

8B Trichomes separate; sheaths not 

confluent Lyngbya 



10 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

9A Heterocysts terminal Cylindrospermum 

9B Heterocysts intercalary Ahphanizomenon 

10A Cell walls without punctae or 

striae 31 

10B Cell walls rigid, ornamented with 
punctae or striae, indestructible 

by clearing techniques 11 

11A Frustules adiametric, two or more times 

longer than wide, generally elongate 15 

11B Frustules isodiametric, generally shorter in 
length than in diameter, round or ellip- 
tical or ovoid or nearly so 12 

12A Frustules elliptical or ovoid or 

nearly so 14 

12B Frustules discoid or nearly so 13 

13A Valves radially punctate Stephanodiscus 

13B Valves with two concentric regions, the in- 
ner being smooth Cyclotella 

14A Frustules with marginal keel 

containing a raphe Surirella 

14B Frustules with a pseudoraphe or 
with a raphe not in a marginal 

keel Cocconeis 

15A Frustules cylindrical arranged end to end 

into filament Melosira 

15B Frustules not arranged into filaments 16 

16A Frustules with a raphe in at least 

one valve 21 

16B Frustules without a raphe in either 

valve, pseudoraphe evident 17 

17A Frustules united in zigzag chains Tabellaria 

17B Frustules not in zigzag chains 18 

18A Frustules united laterally Fragilaria 

18B Frustules not united laterally 19 

19A Frustules united apically forming spokelike 

colony Asterionella 

19B Frustules not forming spokelike colony 20 

20A Frustules needle shaped without 

costae Synedra 

20B Frustules with prominant costae Diatoma 



TAXONOMIC KEY 11 

21A Frustules sigmoid or "S" shaped Gyrosigma 

21B Frustules not sigmoid 22 

22A Frustules longitudinally sym- 
metrical, other than lunate in 

valve view 25 

22B Frustules with raphe in both valves, 
longitudinally asymmetrical, 

lunate in valve view 23 

23 A Valves with transverse costae Epithemia 

23B Valves without transverse costae 24 

24A Raphe a smooth curve with well 

defined central and polar nodules Cymbella 

24B Raphe not a smooth curve, gibbose 

with marginal central nodule Amphora 

25A Frustules with raphe in both valves 27 

25B Frustules with pseudoraphe in one valve and 

raphe in other valve 26 

26 A Frustules wedge-shaped in girdle 

view and cuneate in valve view Rhoicosphenia 

26B Frustules shaped otherwise Achnanthes 

27A Raphe extended length of valve; polar 
nodules evident; central nodules 

lacking Eunotia 

27B Raphe restricted to polar regions 28 

28A Raphe located in a canal Nitzschia 

28B Raphe not located in a canal 29 

29A Frustules with symmetrical valves 30 

29B Frustules with valves longitudinally sym- 
metrical but transversely asym- 
metrical Gomphonema 

30A Valves with transverse costae Pinnularia 

30B Valves with transverse punctae Navicula 

31A Cells solitary 45 

31B Cells colonial or grouped 32 

32A Cells enclosed in conical to cylin- 
drical lorica; joined lorica have 
treelike appearance Dinobryon 



12 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

32B Cells and lorica without treelike ap- 
pearance 33 

33A Colony discoid, one cell in thickness; cells in 

concentric rings Pediastrum 

33B Colony not discoid 34 

34A Colonies spherical or globose 40 

34B Colonies not spherical 35 

35A Colony with elongate cells radiating from 

common center Actinastrum 

35B Colony with cells not radiating from common 

center 36 

36A Colony with (generally) four to 
eight cells positioned in linear 

series Scenedesmus 

36B Colony with cells not in linear series 37 

37A Colony with arcuate to lunate cells with 
apices acutely pointed; convex faces of 

cells apposed Selenastrum 

37B Colony with spherical to broadly ellipsoidal 

cells 38 

38A Cells without spines or setae Crucigenia 

38B Cells with spines or setae 39 

39A Cells quadrate, closely apposed; free face of 

each cell with one or more spines Tetrastrum 

39B Cells quadrate and united; free face of each 
cell with two to seven long delicate 

setae Micractinium 

40A Colony with biflagellated cells Pandorina 

40B Colony with nonflagellated cells 41 

41 A Cells lunate to sickle shaped Kirchneriella 

41 B Cells spherical or nearly so 42 

42A Cells borne terminally on 

dichotomously branched threads Dictyosphaerium 

42B Cells not on dichotomously 

branched threads 43 

43 A Colony a hollow sphere Coelastrum 

43B Colony not a hollow sphere 44 

44A Colony surrounded by partially 
gelatinized and greatly expanded 
parent cell wall Oocystis 



TAXONOMIC KEY 13 

44B Colony with cells equidistant and 

toward periphery Sphaerocystis 

45A Cells with median constriction dividing cell 

into two distinct halves Cosmarium 

45B Cells without pronounced median constric- 
tion 46 

46A Cells nonflagellated 53 

46B Cells flagellated 47 

47A Cell walls without polygonal plates 49 

47B Cell walls with polygonal plates 48 

48A Cells walls of thick plates with 

distinct sutures Peridinium 

48B Cells walls with faintly distinct 

plates and sutures Glenodinium 

49A Cells uniflagellate 52 

49B Cells biflagellate 50 

50A Cells with two flagella of equal 

length Chlamydomonas 

50B Cells with two flagella of unequal 

length 51 

51 A Cells with single chromatophore Chroomonas 

51B Cells with 2 large chromatophores Cryptomonas 

52 A Cells surrounded by distinct lorica Trachelomonas 

52B Cells without lorica; fusiform to 
acicular shaped; posterior end 

more or less pointed Euglena 

53A Cells acicular to fusiform with ends tapering 

into long spines Schroederia 

53B Cells without ends tapering into long spines 54 

54A Cells without setae 56 

54B Cells with setae 55 

55A Cells with subpolar or both subpolar and 

equatorial long setae Chodatella 

55B Cells with multiple peripheral long delicate 

setae Golenkinia 

56A Cells long, slender, and tapered at 

both ends Ankistrodesmus 

56B Cells flattened or isodiametric, 
triangular, quadrangular, or 
polygonal Tetraedron 



14 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

DESCRIPTION OF THE GENERA 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Scenedesmaceae 
GENUS ACTINASTRUM Lagerheim, 1882 (fig. 1) 

MORPHOLOGY 

Cells are ovoid, oblong, or club shaped and radiate from a common 
center. Cell diameter ranges from about 1 to 6 ^m, and cell length 
varies from about 10 to 35 fim. Chromatophores are parietal. Coenobia 
generally contain 4, 8, or 16 cells. 

REPRODUCTION 

The protoplast is divided into 4, 8, or 16 autospores by transverse and 
longitudinal division. The daughter cells, joined in fasciculate bundles, 
are released following rupture of the parent-cell wall. Following 
release, the cells separate outwardly from the point where the cells 
touch. 

OCCURRENCE 

Actinastrum is widely distributed in the euplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 ■ 

pH 5.7 - 

Dissolved oxygen milligrams per liter .8 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 3 

Total hardness do 6 

Total nitrogen do .01- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Smith (1920) and Prescott (1962). 



36.0 


20.8 


7.6 


9.6 


7.8 


.6 


19.7 


8.6 


2.3 


I'.t.NOI) 


958 


2,210 


440 


138 


78 


1,800 


253 


250 


17.0 


1.80 


1.83 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



15 




Figure 1.- Drawing of Actinastrum. 



16 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS ANKISTRODESMUS Corda, 1838; emend., Ralfs, 
1848 (fig. 2) 

MORPHOLOGY 

Cells are acicular to fusiform, straight, curved, or sigmoid. Diameter 
ranges from about 1 to 4 /*m; cells length varies from 15 to 80 fim. Cells 
are generally singular but may be loosely aggregated. The single 
chromatophore is parietal. 

REPRODUCTION 

The cell divides longitudinally into 2, 4, or 8 autospores. 

OCCURRENCE 

Ankistrodesmus is widely distributed in the euplankton, but it rarely 
occurs in abundance. According to Smith (1950), aquariums and other 
receptacles containing water that has been standing in the laboratory 
for some time may contain a virtually unialgal culture of the alga. The 
commonly occurring species, Ankistrodesmus falcatus, is generally 
found in acidic water of high temperature, where there is a dense con- 
glomeration of other algae. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 



Temperature degrees Celsius 0.0 - 36.0 

pH 3.4 - 10.0 

Dissolved oxygen milligrams per liter .1 - 22.0 

Specific conductance micromho 10 -50,000 

Total alkalinity milligrams per liter n 500 

Total hardness do 3 - 2,000 

Total nitrogen do .00- 41.0 

Total phosphorus do .0 - 3.9 



17.4 


8.6 


7.6 


.7 


8.9 


2.5 


857 


1,881 


116 


83 


217 


258 


1.54 


1.80 


.2 


.3 



SPECIES INFORMATION 

Refer to Brunnthaler (1915) and Prescott (1962). 



DESCRIPTION OF THE GENERA 



17 




Figure 2. -Drawing of AnkistrodesrniLs. 



18 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Volvocales 
Family Chlamydomonadaceae 
GENUS CHLAMYDOMONAS Ehrenberg, 1833 (fig. 3) 

MORPHOLOGY 

Actively motile solitary cells are ovoid, spherical, fusiform, or ellip- 
soidal and range from 3 to 10 ^m in diameter. Two equal-lengthed 
flagella are located at the anterior end. Cell contains a single, cup- 
shaped chromatophore and contractile vacuoles. Eyespot may or may 
not be present. 

REPRODUCTION 

The alga reproduces both asexually and sexually. Asexual reproduc- 
tion is by longitudinal division into 2, 4, or 8 daughter cells, which are 
enveloped in an amorphous gelatinous wall. Continued division results 
in the palmella stage. Cells develop flagella and escape through the 
parent-cell wall. Species may be homothallic or heterothallic, and 
gametic union may be isogamous, anisogamous, oogamous. 

OCCURRENCE 

The alga occurs commonly in the euplankton and tychoplankton as 
solitary, free-swimming cells. It has a widespread distribution, but 
generally it is found in calm or very slowly moving waters. 



ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 36.5 

pH 4.1 - 9.8 

Dissolved oxygen milligrams per liter .1 - 22.0 

Specific conductance micromho 10 -49,800 

Total alkalinity milligrams per liter - 500 

Total hardness do 3 - 2,000 

Total nitrogen do .00- 26.0 

Total phosphorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Pascher (1927), Gerloff (1940), and Prescott (1962). 



16.8 


8.9 


7.7 


.7 


9.0 


2.6 


1,185 


3,250 


132 


85 


252 


289 


1.65 


1.86 


.2 


.4 



DESCRIPTION OF THE GENERA 



19 




Figure 3. - Drawing of Chlamydomonas. 



20 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS CHODATELLA Lemmermann, 1898 (fig. 4) 

Generic synonym. -Lagerheimia Chodat, 1895. 

MORPHOLOGY 

Solitary cells are citriform, ellipsoidal, subcylindrical, or subspherical 
and contain long setae that are subpolar, or subpolar and equatorial, in 
insertion. One to four laminate to discoid chromatophores are present. 

REPRODUCTION 

Cells divide into 2, 4, or 8 autospores, which are released 
simultaneously from the parent-cell wall. Setae develop after release. 

OCCURRENCE 

Solitary, free-floating cells are found commonly in the euplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 5.6 - 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 1 1 

Total alkalinity milligrams per liter 3 

Total hardness do 5 

Total nitrogen do .05- 

Total phosphorus do .0 - 



34.0 


19.0 


8.2 


9.5 


7.8 


.6 


20.6 


9.0 


2.4 


21.500 


972 


1,700 


440 


129 


78 


1,800 


249 


254 


26.0 


1.66 


1.92 


3.7 


.2 


.4 



SPECIES INFORMATION 

Refer to Smith (1920, 1926) and Prescott (1962). 



DESCRIPTION OF THE GENERA 



21 




Figure 4. -Drawing of Chodatella. 



22 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Coelastraceae 
GENUS COELASTRUM Nageli, 1849 (fig. 5) 

MORPHOLOGY 

Cells are spherical, ovoid, or pyramidal and range from 3 to 25 fim in 
diameter. Chromatophores are cup shaped to diffuse. Coenobia 
generally are hollow spheres consisting of 4, 8, 16, 32, 64, or 128 cells 
connected by processes of varying length. Sheath is very delicate. 

REPRODUCTION 

One or more cells in the colony divides into 4, 8, 16, 32, 64, or 128 
autospores that remain united. The newly formed colony is released by 
bipartition or quadripartition of the parent-cell wall (Crow, 1925). Oc- 
casionally, a cell develops into an aplanospore, which is released prior 
to division into a new colony. 

OCCURRENCE 

The genus is widely distributed in slowly moving waters. It is an in- 
significant component of algal communities indicating eutrophic condi- 
tions. It often is found sparingly intermingled with other algae in pools 
and ditches (Smith, 1950). 

ENVIRONMENTAL CONDITIONS 



Standard 

Range Mean deviation 

Temperature., degrees Celsius__ 0.0 - 34.0 22.2 6.0 

pH__ 4.2 - 9.4 7.7 .6 

Dissolved oxygen milligrams per liter , .4 - 19.7 8.1 2.2 

Specific conductance micromho . 10 -35,500 808 1,660 

Total alkalinity milligrams per liter__ - 390 120 71 

Total hardness _ do ' 6 - 1,400 212 200 

Total nitrogen do .07- 19.0 1.67 1.90 

Total phosphorus _. do .0 - 3.4 .2 .3 

t 
SPECIES INFORMATION 

Refer to Ducellier (1915), Brunnthaler (1915), and Prescott (1962). 



DESCRIPTION OF THE GENERA 



23 




Figure 5. -Photomicrograph of Coelastrum. 



24 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta. 
Class Chlorophyceae 
Order Zygnematales 
Family Desmidiaceae 
GENUS COSMARIUM Corda, 1834 (fig. 6) 

MORPHOLOGY 

Cells are variable in size, ranging from 9 to 100 ^m in diameter and 
generally are longer than wide. Semicells are elliptical, semicircular, 
subquadrate, or pyramidal. The apex is rounded, truncate, or subtrun- 
cate, without an apical incision. A single, axial chromatophore is 
located in each semicell. The genus is solitary. 

REPRODUCTION 

During sexual reproduction, the protoplasts of 2 conjugating cells 
emerge at each isthmus, unite, and form a zygote. Each zygote 
develops into 2 daughter cells, each of which develops a cell wall before 
being released by rupture of the zygotic wall. 

OCCURRENCE 

There are many species in the genus, which has widespread distribu- 
tion. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 5.2 - 

Dissolved oxygen milligrams per liter .7 - 

Specific conductance mieromho 10 

Total alkalinity milligrams per liter 2 

Total hardness do 6 

Total nitrogen do .09- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to West and West (1905, 1908, 1912). 



34.0 


21.0 


7.2 


10.0 


7.6 


.7 


20.6 


8.3 


2.3 


18,000 


529 


1,150 


430 


89 


70 


1,200 


146 


153 


32.0 


1.31 


2.11 


2.0 


.1 


.2 



DESCRIPTION OF THE GENERA 



25 




Figure 6. - Drawing of Cosmarium. 



26 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Scenedesmaceae 
GENUS CRUCIGENIA Morren, 1830 (fig. 7) 

MORPHOLOGY 

Cells, 4-10 ^m in diameter, are elliptical, triangular, trapezoidal, or 
semicircular in surface view. One to 4 cup-shaped chromatophores are 
situated parietally in each cell. Cells are joined quadrately to form a 
4-celled coenobia. Several coenobia may be enclosed in a gelatinous 
envelope. 

REPRODUCTION 

The protoplast divides into 4 autospores that remain quadrately ap- 
posed. 

OCCURRENCE 

Free-floating colonies occur commonly in the euplankton. It is widely 
distributed. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 4.7 

Dissolved oxygen milligrams per liter .5 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 5 

Total nitrogen do .03- 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Smith (1920, 1926) and Prescott (1962). 



36.0 


19.6 


8.0 


9.6 


7.6 


.7 


22.0 


8.5 


2.4 


-45,500 


716 


1,540 


- 440 


116 


85 


- 1,700 


192 


196 


;- 20.0 


1.46 


1.56 


3.9 


.2 


.3 



DESCRIPTION OF THE GENERA 



27 




Figure 7. - Drawing of Crucigenia. 



28 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS DICTYOSPHAERIUM Nageli, 1849 (fig. 8) 

MORPHOLOGY 

Cells are spherical, ovoid, ellipsoidal, or reniform and range from 3 to 
10 /*m in diameter. Each cell contains a single, cup-shaped, parietal 
chromatophore. Cells are connected by branching threads. Colony is 
embedded in a copious, homogeneous, gelatinous sheath. 

REPRODUCTION 

Antherozoids (generally 16 or 32) from a male colony swarm around 
one of 2 eggs released by a female colony. An antherozoid and an egg 
become laterally fused to form a zygote. Division of the zygote forms a 
daughter colony. Asexual reproduction of a cell into 2 to 4 autospores 
precedes the movement of the daughter cells to the tips of segments 
formed by the partial splitting of the parent-cell wall. 

OCCURRENCE 

The alga is of widespread distribution. It is found most often in soft 
to semihard waters. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 36.0 

pH 4.6 - 9.6 

Dissolved oxygen milligrams per liter .1 - 19.7 

Specific conductance micromho 10 -50,000 

Total alkalinity milligrams per liter - 440 

Total hardness do 5 - 1,900 

Total nitrogen do .00- 19.0 

Total phosphorus do .0 - 2.9 



SPECIES INFORMATION 

Refer to Tiffany (1934), Smith (1920), and Prescott (1962). 



20.0 


7.6 


7.6 


.7 


8.5 


2.3 


814 


1,860 


112 


80 


206 


232 


1.49 


1.55 


.2 


.3 



DESCRIPTION OF THE GENERA 



29 




Figure 8. -Photomicrograph of Dictyosphaerium. 



30 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Micractiniaceae 
GENUS GOLENKINIA Chodat, 1894 (fig. 9) 

MORPHOLOGY 

Solitary cells, 7-15 pcm in diameter, contain numerous, long, slightly 
tapering setae. The single chromatophore is parietal and cup shaped. 

REPRODUCTION 

Two, 4, or 8 autospores are formed and released by fragmentation of 
the parent-cell wall. Sexual reproduction is oogamous. Biflagellate an- 
therozoids swarm around a cell containing a single egg, a part of which 
protrudes through the cell wall. After fusion, the zygote moves through 
the pore and becomes attached to the parent-cell wall. 

OCCURRENCE 

Golenkinia is common in the euplankton. It is present generally in 
shallow, slow-moving waters. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 5.5 

Dissolved oxygen milligrams per liter .1 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 6 

Total hardness do 7 

Total nitrogen do .9 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Tiffany (1934), Smith (1920), and Prescott (1962). 



35.9 


19.9 


8.1 


9.6 


7.7 


.7 


19.7 


8.8 


2.5 


12,000 


688 


1,060 


440 


114 


78 


1,500 


201 


199 


15.0 


1.61 


.09 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



31 




Figure 9. -Drawing of Golenkinia. 



32 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS KIRCHNERIELLA Schmidle, 1893 (fig. 10) 

MORPHOLOGY 

Cells are generally acute or lunate and attenuated. Cell apices are 
often in close proximity. A single chromatophore is parietal on convex 
side of cell or entirely fills the cells. Cells are arranged loosely in groups 
of 4 or 8 within a wide gelatinous envelope. Colony may be as much as 
250 ^im in diameter. 

REPRODUCTION 

Cellular division results in 4 to 8 autospores that separate as the 
parent-cell wall gelatinizes. 

OCCURRENCE 

The genus rarely occurs in great numbers and often is found inter- 
mingled among other algae. It generally is indicative of acidic condi- 
tions. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 ■ 

pH 3.7 - 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 6 

Total hardness do 6 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to West (1908), Smith (1920), and Prescott (1962). 



36.0 


20.0 


7.9 


9.8 


7.7 


.7 


22.0 


8.6 


2.5 


.48,(1(111 


918 


2,350 


470 


119 


80 


2.000 


218 


239 


21.0 


1.61 


1.75 


3.4 


.2 


.3 



DESCRIPTION OF THE GENERA 



33 




Figure 10. -Drawing of Kirchneriella. 



34 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Micractiniaceae 
GENUS MICRACTINIUM Fresenius, 1858 (fig. 11) 

MORPHOLOGY 

Cells are spherical to broadly ellipsoidal and 4-8 ^m in diameter. The 
single, cup-shaped chromatophore is parietal. Each cell bears 1 to 7 
long uniform setae. Cells generally are quadrately united in a 4-celled 
coenobium. Several coenobia are generally united. 

REPRODUCTION 

The cell divides asexually into 4 autospores, which are released when 
the parent-cell wall ruptures into 4 symmetrical parts. Oogamous sex- 
ual reproduction is by the union of a biflagellate antherozoid and an 
egg. The egg protrudes through an opening in the cell wall at the time 
of fertilization. Following fertilization, the zygote moves through the 
opening and becomes attached to the parent-cell wall. 

OCCURRENCE 

Free-floating colonies are common in the euplankton. It is generally 
indicative of soft- water conditions. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 5.9 - 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 11 

Total alkalinity milligrams per liter 

Total hardness do 6 

Total nitrogen do .03- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Tiffany (1934), Smith (1920), and Prescott (1962). 



34.0 


19.0 


7.9 


9.6 


7.8 


.6 


22.0 


8.9 


2.5 


10,200 


761 


1,150 


426 


125 


78 


1,500 


215 


206 


26.0 


1.97 


2.32 


3.9 


.3 


.4 



DESCRIPTION OF THE GENERA 



35 




Figure 1 1 .- Photomicrograph of Micr actinium. 



36 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS OOCYSTIS Nageli, 1855 (fig. 12) 

MORPHOLOGY 

Cells are ovoid, ellipsoidal, or cylindrical; 7-45 /*m in diameter; and 
have smooth walls. A polar nodule may be present. The number of 
chromatophores varies from 1 to many. The genus may be solitary or in 
colonies of 2, 4, 8, or 16 cells surrounded by a partially gelatinous and 
greatly swollen parent-cell wall. 

REPRODUCTION 

Reproduction is asexual into 2, 4, 8, or 16 autospores. Sister 
autospores remain within the greatly expanded parent-cell wall and 
may be accompanied by several groupings of sister autospores. New 
colonies are formed by the rupturing of the parent-cell wall. 

OCCURRENCE 

Oocystis is widely distributed in the euplankton and tychoplankton. It 
generally is indicative of soft water or oligotrophic water. Some species 
(for example, Oocystis ellvptica) are commonly found in warm shallow 
water intermingled among other algae. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 4.4 

Dissolved oxygen milligrams per liter 1.7 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 1 

Total hardness do 7 

Total nitrogen do .0( 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Smith (1920), Printz (1913), and Prescott (1962). 



36.0 


19.6 


8.0 


9.8 


7.8 


.6 


22.0 


8.7 


2.4 


- ss, nun 


1.120 


2,730 


- 440 


129 


76 


- 2,000 


242 


247 


l- 19.0 


1.53 


1.59 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



37 




Figure 12. -Photomicrograph of Oocystis. 



38 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Volvocales 
Family Volvocaceae 
GENUS PANDORINA Bory, 1824 (fig. 13) 

MORPHOLOGY 

Cells are pyriform, spherical, or angular and generally 7-18 fim in 
diameter. Each cell had 2 flagella of equal length. The single 
chromatophore is cup shaped. Four, 8, 16, or 32 cells are mutually com- 
prised in the periphery of a colony and enclosed by a copious, 
homogeneous envelope. 

REPRODUCTION 

Following a state of colonial dormancy, all cells within the colony 
undergo simultaneous division into daughter colonies. Each cell of the 
daughter colony develops 2 flagella, and a new colony is formed. Sexual 
reproduction is anisogamous. Free-swimming male gametes fuse ter- 
minally or laterally with somewhat larger free-swimming female 
gametes. The quadriflagellate zygote looses its flagella and develops a 
cell wall. Zygote development results in biflagellate zoospores, which 
secrete a gelatinous envelope and divide into a new colony. 

OCCURRENCE 

The alga is rarely found in abundance but frequently occurs in the 
euplankton of hard bodies of water. It also is found frequently among 
dense growths of algae in shallow waters rich in nitrogenous matter 
(Prescott, 1962). 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 5.2 - 

Dissolved oxygen milligrams per liter 1.3 - 

Specific conductance micromho 11 

Total alkalinity milligrams per liter 7 

Total hardness do 6 

Total nitrogen do .01- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Smith (1920, 1931) and Prescott (1962). 



33.0 


22.1 


6.9 


9.0 


7.6 


.7 


20.0 


7.9 


2.4 


11,800 


612 


993 


390 


117 


78 


1,700 


181 


175 


13.0 


1.4 


1.4 


3.1 


.2 


.3 



DESCRIPTION OF THE GENERA 



39 




Figure 13. -Drawing of Pandorina. 



40 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Hydrodictyaceae 
GENUS PEDIASTRUM Meyen, 1829 (fig. 14) 

MORPHOLOGY 

Cells are coenocytic with smooth or rough walls. Peripheral cells are 
shaped differently from interior cells and have 1 or 2 processes. 
Chromatophores are discoid to diffuse. Coenobia are plate shaped and 
consist of 4, 8, 16, 32, 64, 128, or 256 cells and may be as much as 450 
^m in diameter. 

REPRODUCTION 

Biflagellate zoospores formed by several cells in the colony are con- 
tained in a vesicule of the parent-cell wall. The vesicule remains until 
the new colony is formed and released. Isogamous sexual reproduction 
is by a fusion of spindle-shaped biflagellate gametes formed like the 
zoospores. 

OCCURRENCE 

The genus is widely distributed in the euplankton and tychoplankton 
of all types of waters. Some species are indicative of particular en- 
vironmental conditions; for example, Pediastrum simplex is indicative 
of oligotrophic waters, whereas Pediastrum duplex or Pediastrum 
Boryanum are indicative of eutrophic waters. The genus can occur in 
great numbers. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 4.9 - 

Dissolved oxygen milligrams per liter 1.1 - 

Specific conductance micromho__ 30 

Total alkalinity milligrams per liter 4 

Total hardness do 5 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Brunnthaler (1915), Bigeard (1933), Harper (1916, 1918), 
and Prescott (1962). 



34.0 


20.7 


7.2 


9.8 


7.7 


.6 


20.0 


8.4 


2.3 


14,000 


616 


841 


440 


119 


74 


1,400 


189 


157 


24.0 


1.6 


2.0 


3.6 


.2 


.4 



DESCRIPTION OF THE GENERA 



41 




Figure 14. -Photomicrograph of Pediastrum. 



42 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Scenedesmaceae 
GENUS SCENEDESMUS Meyen, 1829 (fig. 15) 

MORPHOLOGY 

Cells are ellipsoidal, oblong, fusiform, acicular, or ovoid. The single 
chromatophore is parietal. Cell walls are smooth, corrugated, 
granulate, or spicate with or without marginal or lateral teeth or 
spines. Coenobia are flat and consist of 2, 4 (most commonly), or 8 cells 
but sometimes as many as 16 or 32 cells. 

REPRODUCTION 

Transverse and longitudinal divisions into 2, 4, 8, 16, or 32 
autospores are undertaken by a parent cell. The parent-cell wall splits 
longitudinally, releasing the daughter colony. 

OCCURRENCE 

The genus is widely distributed in the euplankton, tychoplankton, 
and periphyton. It is found in all types of waters. The commonly occurr- 
ing species, Scenedesmus quadricauda, is one of the most nearly ubi- 
quitous algal species. Great numbers, so as to color the water green, 
may occur in small pools. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 



Temperature degrees Celsius 0.0 - 37.0 18.1 8.4 

pH 3.4 - 10.0 7.6 .7 

Dissolved oxygen milligrams per liter .1 - 22.0 8.7 2.5 

Specific conductance micromho__ 10 -48,000 863 1,800 

Total alkalinity milligrams per liter - 480 119 80 

Total hardness do 3 - 2,000 221 254 

Total nitrogen do .00- 26.0 1.6 2.0 

Total phosphorus.. do .0 - 4.0 .2 .3 

SPECIES INFORMATION 

Refer to Chodat (1926), Smith (1916), and Prescott (1962). 



DESCRIPTION OF THE GENERA 




Figure 15. -Photomicrograph of Scenedesmus. 



44 



ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 



Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Characiaceae 
GENUS SCHROEDERIA Lemmermann, 1899 (fig. 16) 

MORPHOLOGY 

Solitary cells are acicular to fusiform and are straight or slightly 
curved. Cell apices are tapered into setae; one may be bifurcate. Total 
cell length, including setae, may exceed 150 /mi. The single 
chromatophore is H -shaped. Eyespot may or may not be present. 

REPRODUCTION 

Biflagellate zoospores (4 or 8) form within the cell and are released by 
transverse splitting of the parent-cell wall. The zoospore loses its 
flagella and develops into a vegetative cell. 

OCCURRENCE 

The solitary, free-floating cells of the genus are found in the 
euplankton. 

ENVIRONMENTAL CONDITIONS 



Range 



Mean 



Standard 

deviation 



Temperature degrees Celsius 0.0 

pH 5.3 

Dissolved oxygen milligrams per liter .1 

Specific conductance micromho 10 

Total alkalinity milligrams per liter__ 

Total hardness do 6 

Total nitrogen do 00 

Total phosphorus do .0 



36.0 


20.0 


8.0 


9.6 


7.7 


.6 


211.7 


8.2 


2.2 


35,000 


899 


2,145 


100 


124 


78 


1,700 


216 


227 


17.0 


1 .55 


1.81 


3.5 


:i 


.4 



SPECIES INFORMATION 

Refer to Smith (1920, 1926) and Prescott (1962). 



DESCRIPTION OF THE GENERA 



45 




Figure 16. -Drawing of Schroederia. 



46 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS SELENASTRUM Reinsch, 1867 (fig. 17) 

MORPHOLOGY 

Cells are arcuate to lunate with apices acutely pointed. The single 
chromatophore is parietal. Convex surfaces of 4, 8, or 16 cells are ap- 
posed; a colony may have as many as 100 or more cells. There is no 
gelatinous envelope. 

REPRODUCTION 

The cell contents divide into 4, 8, or 16 autospores, which generally 
remain opposed to one another following release from the parent-cell 
wall. 

OCCURRENCE 

Selenastrum is widely distributed in the euplankton. It is found spar- 
ingly intermingled with other free-floating algae in pools and other 
quiet waters (Smith, 1950). Some species occur in soft, acidic waters. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 4.4 - 

Dissolved oxygen milligrams per liter .4 ■ 

Specific conductance micromho 25 

Total alkalinity milligrams per liter 

Total hardness do 4 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Collins (1909), Smith (1920), and Prescott (1962). 



33.5 


19.1 


7.7 


9.4 


7.7 


.7 


18.3 


8.5 


2.4 


24,800 


723 


1,280 


500 


118 


81 


2,000 


203 


206 


17.0 


1.57 


1.55 


3.6 


.2 


.4 



DESCRIPTION OF THE GENERA 



47 




Figure 17. -Drawing of Selenastrum. 



48 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Tetrasporales 
Family Palmellaceae 
GENUS SPHAEROCYSTIS Chodat, 1897 (fig. 18) 

MORPHOLOGY 

Cells are spherical and are as much as 25 /im in diameter. Cup- 
shaped chromatophores may fill entire cell. The spherical colony con- 
sists of groups of 4, 8, 16, or 32 cells arranged toward the periphery of 
a hyaline, homogeneous envelope. 

REPRODUCTION 

A colonial cell divides into 4 or 8 daughter cells, which are enveloped 
in a distinct gelatinous envelope. The daugher colony is released by a 
softening of the parent-colony matrix. 

OCCURRENCE 

The genus is widely distributed in the euplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.3 

pH 4.9 - 9.3 

Dissolved oxygen milligrams per liter .4 - 15.9 

Specific conductance micromho 10 -9,800 

Total alkalinity milligrams per liter 6 - 400 

Total hardness do 5 -1,800 

Total nitrogen do .05- 17. n 

Total phosphorus do .0 - 2.8 

SPECIES INFORMATION 

Refer to Smith (1920) and Prescott (1962). 



20.9 


6.7 


7.6 


.7 


8.2 


2.1 


689 


1.29(1 


107 


80 


189 


237 


1.49 


1.93 


2 


■> 



DESCRIPTION OF THE GENERA 



49 



-r* - 



tW ^.. 




•*».%.,«., j ■*• 



Figure 18. -Drawing of Sphaerocystis. 



50 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Oocystaceae 
GENUS TETRAEDRON Kutzing, 1845 (fig. 19) 

MORPHOLOGY 

Solitary cells are polyhedral. Angles of the cells may be simple or pro- 
duced into simple or furcate processes. Cell wall may be smooth or ver- 
rucose. Cell may contain 1 to many parietal discoid to angular 
chromatophores. 

REPRODUCTION 

The cell divides into 2, 4, 8, 16, or 32 autospores, which are im- 
mediately released by rupture of the parent-cell wall. 

OCCURRENCE 

The genus is widely distributed, particularly in the euplankton and 
tychoplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 4.7 

Dissolved oxygen milligrams per liter .4 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 6 

Total nitrogen do .03 

Total phospnorus do .0 



SPECIES INFORMATION 

Refer to Brunnthaler (1915), Reinsch (1888), Smith (1920, 1926), and 
Prescott (1962). 



34.0 


20.8 


6.8 


9.6 


7.7 


.6 


20.7 


8.3 


2.3 


-14,800 


698 


1,130 


- 440 


114 


75 


- 1,800 


189 


184 


;- 21.0 


1.37 


1.50 


2.9 


.2 


.3 



DESCRIPTION OF THE GENERA 



51 




Figure 19. -Drawing of Tetraedron. 



52 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chlorophyta 
Class Chlorophyceae 
Order Chlorococcales 
Family Scenedesmaceae 
GENUS TETRASTRUM Chodat, 1895 (fig. 20) 

MORPHOLOGY 

Cells, 4-10 pcm. in diameter, are elliptical, triangular, trapezoidal, or 
semicircular. Each cell has one or more spines on the free face. One to 4 
cup-shaped chromatophores are parietal. Cells are joined quadrately to 
form a 4-celled coenobia. 

REPRODUCTION 

A cell divides into 4 autospores that remain quadrately attached. 
Cellular spines develop following release by rupture of the parent-cell 
wall. 

OCCURRENCE 

Tetrastrum has a widespread distribution, but it is found generally 
only in very few numbers. It is common in the euplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 4.9 • 

Dissolved oxygen milligrams per liter 1.7 ■ 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 2 

Total hardness do 5 

Total nitrogen do .01- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Ahlstrom and Tiffany (1934) and Prescott (1962). 



34.0 


19.1 


7.8 


9.4 


7.8 


.6 


19.7 


8.8 


2.3 


9,800 


741 


998 


477 


129 


76 


2,000 


215 


184 


19.0 


1.72 


1.71 


3.7 


.2 


.3 



DESCRIPTION OF THE GENERA 



53 




Figure 20. - Drawing of Tetrastrum. 



54 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Euglenophyta 
Class Euglenophyceae 
Order Euglenales 
Family Euglenaceae 
GENUS EUGLENA Ehrenberg, 1838 (fig. 21) 

MORPHOLOGY 

Cell is elongate, oblong, lanceolate, or spindle shaped; rigidly or 
spirally twisted; solitary; sometimes attenuate at posterior end; and as 
much as 450 fim in length. Each cell contains a single flagellum. A cell 
has a gullet at the anterior end and one or more contractile vacuoles ad- 
joining a flask-shaped reservoir. Eyespot is generally present. 
Chromatophores are numerous and discoid to band shaped. 

REPRODUCTION 

Reproduction is by longitudinal division of the cell beginning at the 
anterior end. Occasionally, a cell becomes immobile and surrounded by 
a gelatinous sheath, following which cell division occurs. This is called a 
palmelloid colony. 

OCCURRENCE 

Euglena is of widespread distribution mostly in the tychoplankton. It 
is very indicative of waters rich in organic matter, for example, those 
below domestic sewage outfalls. It can occur in such abundance as to 
color the water a deep green (Smith, 1950). Occasionally, the light- 
induced production of haematochrome in abundant cells will color a 
body of water brick red (Prescott, 1962). 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 4.1 - 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .01- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Johnson (1944) and Prescott (1962). 



36.0 


18.3 


8.4 


10.0 


7.7 


.6 


22.0 


8.6 


2.8 


48,000 


1,240 


2,680 


500 


146 


88 


2,000 


284 


299 


28.0 


2.11 


2.59 


4.0 


.3 


.5 



DESCRIPTION OF THE GENERA 



55 










v 



> 



^ 



/? 



Figure 21. -Photomicrograph of Euglena. 



56 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Euglenophyta 
Class Euglenophyceae 
Order Euglenales 
Family Euglenaceae 
GENUS TRACHELOMONAS Ehrenberg, 1833 (fig. 22) 

MORPHOLOGY 

Cell is solitary and uniflagellate and loosely encased in a globose or 
ellipsoidal lorica. The surface of the lorica may be smooth, punctate, 
spiny, reticulate, or striate. There are 2 to 15 parietal, discoid 
chromatophores. 

REPRODUCTION 

Prior to division into 2 daughter cells, the parent cell becomes im- 
mobile. One daughter cell is released to form a new lorica. The remain- 
ing daughter cell retains the parent-cell lorica. 

OCCURRENCE 

The genus is very indicative of warm waters having a high content of 
organic matter. It can occur in such abundance as to color the water 
brown. It is found primarily in the tychoplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 ■ 

pH 4.0 - 

Dissolved oxygen milligrams per liter .2 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .02- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Deflandre (1926), Skvortzow (1925), and Prescott (1962). 



34.0 


18.3 


8.5 


9.8 


7.6 


.7 


20.6 


8.6 


2.6 


48,000 


753 


1,970 


500 


113 


83 


1.800 


197 


222 


38.0 


1.60 


1.87 


3.6 


.2 


.3 



DESCRIPTION OF THE GENERA 



57 




Figure 22. -Photomicrograph of Trachelomonas. 



58 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Achnanthaceae 
GENUS ACHNANTHES Bory, 1822 (fig. 23) 

MORPHOLOGY 

Cells are rectangular and longitudinally bent or curved in girdle 
view. They generally are attached by gelatinous stalks or are sessile 
and united into bundles at the valves, rarely into filaments. Values are 
generally linear-lanceolate to elliptical. The epitheca is convex and has 
a pseudoraphe; the hypotheca is commonly concave and has a raphe, in- 
conspicuous polar nodules, a distinct center nodule, and sometimes a 
stauros. Striae are transverse or radiate. Costae are prominant in some 
species. There are 1, 2, or numerous discoid chromatophores. 

REPRODUCTION 

Auxospore formation is by conjugation of paired gametes, 2 of which 
are formed from each of 2 protoplasts. 

OCCURRENCE 

The genus is widely distributed. Freshwater species are generally 
epiphytic upon filamentous chlorophytes and submerged phanerogams. 
They are found frequently in the tychoplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.5 

pH 3.4 - 9.7 

Dissolved oxygen milligrams per liter .8 - 20.6 

Specific conductance micromho 10 -37,400 

Total alkalinity milligrams per liter - 480 

Total hardness do 5 - 2,000 

Total nitrogen do .00- 32.0 

Total phospnorus do .0 - 3.5 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



13.4 


8.3 


7.5 


.7 


9.7 


2.4 


539 


1,290 


95 


76 


164 


226 


1.12 


1.42 


.1 


.3 



DESCRIPTION OF THE GENERA 



59 




Figure 23. - Photomicrograph of Achnanthes. 






60 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Cymbellaceae 
GENUS AMPHORA Ehrenberg, 1840 (fig. 24) 

MORPHOLOGY 

Cells are commonly sessile, with concave faces attached in girdle 
view. They are broadly elliptical in outline and have truncated ends. 
Girdles generally are separated by several punctate or striate inter- 
calary bands. Values are lunate, longitudinally asymmetrical, and 
transversely striate. Raphe is gibbous, with a central nodule close to 
the concave margin. Some species have a single chromatophore which 
lies next to the concave girdle face; other species have 2 or 4 
chromatophores. 

REPRODUCTION 

Two gametes are formed from the protoplast of 2 approximate cells 
and unite to form 2 auxospores. Geitler (1929) observed the production 
of a single auxospore from a single cell. 

OCCURRENCE 

Amphora is widely distributed. Freshwater species commonly are 
found in circumneutral waters having a fairly high nutrient content. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 



Temperature degrees Celsius__ 0.0 - 

PH 4.9 

Dissolved oxygen milligrams per liter 2.7 - 

Specific conductance micromho__ 22 

Total alkalinity milligrams per liter ■ 

Total hardness do 4 

Total nitrogen do .00- 

Total phosphorus do .0 - 



SPECIES INFORMATION 

Refer to Cleve (1895) and Boyer (1927a). 



34.0 


14.3 


8.4 


9.6 


7.8 


.6 


20.0 


9.6 


2.3 


48,600 


1,860 


5,500 


480 


137 


81 


2,000 


269 


281 


38.0 


1.64 


2.50 


3.6 


.2 


.4 



DESCRIPTION OF THE GENERA 



61 




Figure 24. -Photomicrograph of Amphora. 



62 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Fragilariaceae 
GENUS ASTERIONELLA Hassall, 1850 (fig. 25) 

MORPHOLOGY 

Cells are joined to one another at their ends to form flat stellate col- 
onies. Cell length may reach 130 /*m; cell diameter is about 1-2 ^m. 
Valves are linear with inflated ends and are symmetrical in valve and 
girdle views. They are finely transversely striated. Intercalary bands, 
septa, and costae are lacking. The pseudoraphe is indistinct. There are 
2 (generally) to several lobed chromatophores. 

REPRODUCTION 

Reproduction is probably by the formation of an auxospore within a 
single cell. 

OCCURRENCE 

Asterionella is a commonly occurring alga in the euplankton. It is in- 
dicative of mesotrophic to eutrophic conditions. They may occur in such 
abundance as to impart a fishy taste to the water (Whipple and others, 
1948). 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 



Temperature degrees Celsius__ 0.0- 31.0 10.6 7 5 

pH 4.7 - 9.4 7.6 .6 

Dissolved oxygen milligrams per liter 2.0 - 16.6 10.3 2.2 

Specific conductance micromho__ 19 -8,000 342 389 

Total alkalinity milligrams per liter - 371 92 63 

Total hardness do 2 -1,400 127 104 

Total nitrogen do .01- 14.0 1.13 1.14 

Total phosphorus do .0-2.3 .1 .1 

SPECIES INFORMATION 

Refer to Meister (1912), Boyer (1927a), and Patrick and Reimer 
(1966). 



DESCRIPTION OF THE GENERA 



63 




Figure 25. -Photomicrograph of Aster ionella. 



64 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyce?e 
Order Pennales 
Family Achnanthaceae 
GENUS COCCONEIS Ehrenberg, 1838 (fig. 26) 

MORPHOLOGY 

Solitary cells are transversely rurved in girdle visw and broadly ellip- 
tical in valve view. Epitheca has an axial pseudoraphe and transverse 
striae or punctae. Hypotheca has a median raphe that is straight or 
sigmoid and has a central or polar nodule. Striae and punctae generally 
are transverse. A single, laminate chromatophore adjoins the epitheca. 



A single auxospore is formed by the conjugation of 2 approximate 

alio 



OCCURRENCE 



Species of the genus are almost exclusively epiphytic upon filamen- 
tous chlorophytes. It is widely distributed. Occurrence of the genus in 
the plankton generally results from sloughing of the periphyton. 



ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 



Temperature degrees Celsius 0.0 - 34.0 

pH 4.1 - 10.0 

Dissolved oxygen milligrams per liter .8 - 20.0 

Specific conductance micromho 10 -48,000 

Total alkalinity milligrams per liter - 480 

Total hardness do 4 - 2,000 

Total nitrogen do .00- 38.0 

Total phosphorus do .0 - 3.9 



14.4 


8.5 


7.7 


.6 


9.4. 


2.3 


578 


1,450 


114 


75 


169 


165 


1.19 


1.63 


.2 


.3 



SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



DESCRIPTION OF THE GENERA 



65 




' 







:; 



• . 




Figure 26. -Scanning electronmicrograph of Coccorwis. 




% ft 



m 



66 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Centrales 
Family Coscinodiscaceae 
GENUS CYCLOTELLA Kiitzing, 1834 (fig. 27) 

MORPHOLOGY 

Discoid, drum-shaped cells are solitary (generally), filamentous, or in 
a colonial gelatinous envelope. The valve view is circular or rarely ellip- 
tical. Ornamentation is in 2 concentric regions: the outer region is 
radially striate or punctate, and the inner region is smooth or very fine- 
ly punctate. Intercalary bands are lacking. There are numerous small, 
discoid chromatophores. 

REPRODUCTION 

A single auxospore is formed within a cell. 

OCCURRENCE 

The genus is widely distributed in all types of surface waters. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius__ 0.0 - 37.0 

pH 3.4 - 10.0 

Dissolved oxygen milligrams per liter .1 - 22.0 

Specific conductance micromho__ 10 -49.800 

Total alkalinity milligrams per liter - 500 

Total hardness do 3 - 2,000 

Total nitrogen do .00- 41.0 

Total phosphorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



16.1 


8.7 


7.7 


.6 


9.1 


2.5 


918 


2,570 


119 


78 


217 


250 


1.58 


1.96 


.2 


.4 



DESCRIPTION OF THE GENERA 



67 




Figure 27. -Scanning electronmicrograph of Cyclotella. 



68 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Cymbellaceae 
GENUS CYMBELLA Agardh, 1830 (fig. 28) 

MORPHOLOGY 

Solitary cells are free floating, attached at the ends of gelatinous 
stalks, or contained within branched gelatinous tubes. Cell is 
longitudinally asymmetrical in valve view and is lunate, subellipitical, 
rhombic, or naviculoid. It is ventrally concave and dorsally convex. The 
raphe is curved and contains well-defined nodules. Ornamentations 
consist of radiating transverse striae or punctae. Intercalary bands are 
lacking. A single chromatophore is plate shaped. 

REPRODUCTION 

Two gamates are formed from the protoplast of 2 approximate cells 
and unite to form 2 auxospores. 

OCCURRENCE 

A distinctly freshwater genus, Cymbella is widely distributed in the 
euplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 3.4 - 

Dissolved oxygen milligrams per liter 1.1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .00- 

Total phospnorus do .0 - 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



34.0 


13.5 


8.2 


10.0 


7.6 


.7 


20.6 


9.7 


2.2 


49,800 


647 


2,250 


430 


100 


74 


2,000 


164 


194 


28.0 


1.17 


1.53 


3.9 


.1 


.3 



DESCRIPTION OF THE GENERA 



69 












, ... 












^ 



I 






Figure 28. -Photomicrograph of Cymbella. 



70 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Diatomaceae 
GENUS DIATOMA DeCandolle, 1805 (fig. 29) 

MORPHOLOGY 

Cells are rectangularly tabular in girdle view and united at the corner 
into free-floating or sessile zigzag to linear chains. There are 1 to 2 in- 
tercalary bands. Several transverse septa appear as transverse costae. 
Cells are lanceolate to linear and bilaterally symmetrical. Valves con- 
tain transverse, finely punctate striations between the costae. The nar- 
row pseudoraphe does not have a median expansion. Numerous 
chromatophores are elliptical. 

REPRODUCTION 

A single auxospore is formed within a cell. 

OCCURRENCE 

The genus is widely distributed in cool water. Some species are in- 
dicative of particular environmental conditions. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius. _ 0.0 - 34.0 

pH 4.4 - Hi.lt 

Dissolved oxygen milligrams per liter 1.2 - 20.6 

Specific conductance micromho__ 12 -43,400 

Total alkalinity milligrams per liter - 420 

Total hardness do 3 - 1,600 

Total nitrogen __do .00- 41.0 

Total phosphorus do .0 - 3.9 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



11.3 


8.1 


7.8 


.6 


lll.l 


2.3 


599 


1,400 


120 


71 


182 


160 


1.38 


l 98 


.2 


.3 



DESCRIPTION OF THE GENERA 



71 




Figure 29. -Photomicrograph of Diatoma. 



72 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Chrysophyceae 
Order Chrysomonadales 
Family Ochromonadaceae 
GENUS DINOBRYON Ehrenberg, 1835 (fig. 30) 

MORPHOLOGY 

Cells are free floating, sessile, or ephiphytic and may be solitary or in 
colonies. They are enclosed in conical, campanulate, or cylindrical 
cellulose lorica, which have smooth or undulate walls, pointed bases, 
and open tops. Colonies may be arbuscular, divergent, or compact. The 
conical or ovoid protoplast is attached to the base or side of the lorica 
and contains 2 flagella of unequal length. Each cell has 1 to 2 elongate, 
parietal, golden-brown chromatophores, several contractile vacuoles, 
and 1 apical eyespot. 

REPRODUCTION 

Longitudinal division of a cell results in 2 daughter cells, which 
become attached to the mouth of the parent-cell lorica. New lorica are 
formed. Pascher (1943) observed both palmelloid stages and 
statospores. 

OCCURRENCE 

Dinobryon is widely distributed and generally is indicative of hard 
waters. It commonly is intermingled with other algae in pools and dit- 
ches (Smith, 1950). 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.5 

pH 4.1 - 9.0 

Dissolved oxygen milligrams per liter .7 - 14.7 

Specific conductance micromho 11 -7,700 

Total alkalinity milligrams per liter - 477 

Total hardness do 5 -1,700 

Total nitrogen do .00- 12.0 

Total phospnorus do .0- 2.1 

SPECIES INFORMATION 

Refer to Ahlstrom (1937). 



13.6 


8.3 


7.4 


.7 


9.7 


2.4 


313 


447 


83 


72 


122 


134 


.91 


.99 


.1 


.1 




DESCRIPTION OF THE GENERA 73 



%f (;■ 



-$ 



// 



l ■ 






ffl ^ % ^ 



s 






Figure 30. -Photomicrograph of Dinobry on. 



74 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Cymbellaceae 
GENUS EPITHEMIA de Brebisson, 1838 (fig. 31) 

MORPHOLOGY 

The solitary cells are commonly epiphytic upon submerged 
macrophytes. They are attached at the girdle, are rectangular in girdle 
view, and have smooth girdles and intercalary bands. Valves are slight- 
ly to strongly curved dorsally convex, and ventrally straight to con- 
cave. Poles are broadly rounded to capitate and sometimes recurved. 
The axial field is next to the concave side, but its central portion bends 
sharply inward to form a V-shaped structure midway between the 
poles. A raphe contains polar and central nodules. Transverse septa ap- 
pear as costae and alternate with 2 or more rows of punctae. There is 
generally a single chromatophore next to the concave girdle side, which 
has irregular projections extending along both valve faces. 

REPRODUCTION 

Protoplasts of approximate frustules each form 2 gametes, which 
unite to form 2 auxospores. 

OCCURRENCE 

The genus is widely distributed, particularly in the tychoplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 3.7 

Dissolved oxygen milligrams per liter 3.9 

Specific conductance micromho 30 

Total alkalinity milligrams per liter 

Total hardness do 5 

Total nitrogen do .00 

Total phospnorus do .0 

SPECIES INFORMATION 

Refer to Meister (1912), Boyer (1927a), and Patrick and Reimer 
(1966). 



32.0 


11.9 


7.6 


9.2 


7.8 


.6 


15.1 


10.0 


2.1 


in. inn 


630 


2,360 


350 


111 


65 


- 1,700 


149 


147 


i- 36.0 


1.11 


2.17 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



75 




Figure 31. -Scanning electronmicrograph of Epithemia. 



76 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Eunotiaceae 
GENUS EUNOTIA Ehrenberg, 1837 (fig. 32) 

MORPHOLOGY 

Cells are solitary or joined valve to valve into chains. They are free 
floating or epiphytic. Cells are rectangular, linear, or tabular in girdle 
view. Both girdles and valves are strongly ornamented, generally with 
intercalary bands. Valves are arcuate having similar poles and 
dissimilar margins. The concave side is regular; the convex side is in- 
flated slightly near the poles and is regular or undulate. A short raphe 
extends from evident polar nodules diagonally to the concave side. 
There are no central nodule, costae, nor septae. Two chromatophores 
are laminate. 

REPRODUCTION 

A single auxospore is formed by the conjugation of protoplasts from 
2 approximate cells. 

OCCURRENCE 

The genus is found commonly in bodies of soft water and in slowly 
moving waters. They are frequently found in oligotrophic or dystrophic 
waters (Patrick and Reimer, 1966). 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH _ 3.4 

Dissolved oxygen milligrams per liter .8 

Specific conductance micromho 23 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .06 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



31.0 


14.2 


8.2 


8.7 


6.8 


.9 


15.2 


9.1 


2.4 


-45,500 


283 


1,816 


- 330 


44 


58 


- 680 


65 


101 


8.5 


.92 


.79 


2.1 


.1 


.2 



DESCRIPTION OF THE GENERA 



77 




Figure 32. - Drawing of Eunotia. 



78 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Fragilariaceae 
GENUS FRAGILARIA Lyngbye, 1819; emend., Rabenhorst, 
1864 (fig. 33) 

MORPHOLOGY 

Cells are linear to fusiform, bilaterally symmetrical, commonly at- 
tenuated at the poles, sometimes capitate, and often medially inflated. 
Cells are rectangular in girdle view and have 0, 1, or 2 intercalary 
bands. They are united into free-floating or sessile colonies, which are 
generally zigzag chains but sometimes are flat, stellate colonies. The 
pseudoraphe is narrow and indistinct or broad and prominent. 
Transverse striae or punctae are present. Chromatophores are 
numerous small discoid bodies or 1 to 4 laminate plates. 

REPRODUCTION 

A single auxospore is formed within a cell. 

OCCURRENCE 

Fragilaria is widely distributed. It generally is indicative of alkaline 
waters of moderate conductivity. The genus is found in the littoral 
zone, as well as in the euplankton (Patrick and Reimer, 1966). 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.5 

pH 3.4 - 10.0 

Dissolved oxygen milligrams per liter 2.0 - 18.7 

Specific conductance micromho 22 -41,000 

Total alkalinity milligrams per liter - 480 

Total hardness do 5 - 1,800 

Total nitrogen,. do .00- 28.0 

Total phospnorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



13.5 


8.4 


7.6 


.7 


9.6 


2.4 


491 


1,130 


99 


69 


149 


163 


1.17 


1.48 


.2 


.3 



DESCRIPTION OF THE GENERA 



79 




Figure 33. -Photomicrograph of Fragilaria. 



80 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Gomphonemataceae 
GENUS GOMPHONEMA Agardh, 1824 (fig. 34) 

MORPHOLOGY 

Cells are commonlyy epiphytic on the ends of dichotomously branch- 
ed gelatinous stalks. They are sometimes sessile or solitary and free 
floating. Cells are transversely asymmetrical in both valve and girdle 
views. Cells are straight, lanceolate, or clavate. One pole is capitate or 
broader than the other. Intercalary bands are lacking. The raphe is 
straight and central and polar nodules are conspicuous. Striations are 
strictly transverse or somewhat radial. The chromatophore is a single, 
lobed plate. 

REPRODUCTION 

The protoplasts of 2 cells each form 2 gametes, which unite to form 2 
auxospores. 

OCCURRENCE 

The alga is widely distributed. Freshwater species are generally 
epiphytic, but they occur commonly in the euplankton and 
tychoplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 4.3 

Dissolved oxygen milligrams per liter .8 

Specific conductance micromho 12 

Total alkalinity milligrams per liter 

Total hardness do 4 

Total nitrogen do .00- 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



36.0 


13.0 


8.3 


10.0 


7.6 


.7 


20.6 


9.8 


2.4 


37.400 


574 


1,260 


491 


105 


80 


1,800 


171 


203 


32.0 


1.43 


1.93 


3.9 


.2 


.4 



DESCRIPTION OF THE GENERA 



81 




Figure 34. -Photomicrograph of Gomphonema. 



82 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Naviculaceae 
GENUS GYROSIGMA Hassall, 1845; emend., Cleve, 1894 (fig. 
35) 

MORPHOLOGY 

Cells generally are solitary and free floating, sometimes in gelatinous 
tubes. They are elliptical to lanceolate in girdle view. Cells are sigmoid 
in outline and generally attenuated toward the acute or broadly round- 
ed poles. Intercalary bands and septa are lacking. The sigmoid raphe 
has small central and polar nodules. Transverse striations cross 
longitudinal striations at right angles. There are two chromatophores, 
which are smooth or irregularly shaped plates. 

REPRODUCTION 

The protoplasts of 2 approximate cells each form 2 gametes. Con- 
jugation results in the formation of 2 auxospores. 

OCCURRENCE 

The genus is widely distributed. It generally is indicative of alkaline 
waters. Some species can tolerate brackish conditions. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 34.0 

pH 4.3 - 9.0 

Dissolved oxygen milligrams per liter 1.1 - 19.3 

Specific conductance micromho 32 -47,800 

Total alkalinity milligrams per liter - 386 

Total hardness do 8 - 2,000 

Total nitrogen do .06- 27.0 

Total phospnorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



16.3 


8.7 


7.6 


.6 


9.0 


2.3 


,310 


3,610 


129 


80 


262 


305 


1.84 


2.15 


.3 


.4 



DESCRIPTION OF THE GENERA 



83 




Figure 35. -Photomicrograph of Gyrosigma. 



84 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Centrales 
Family Coscinodiscaceae 
GENUS MELOSIRA Agardh, 1824 (fig. 36) 

MORPHOLOGY 

Cells are cylindrical and united into long filaments. Cell length is 
greater than width. Valve view is circular. Valves may be flat or con- 
vex. If convex, they generally have a marginal ring of denticulations 
that unite cells into filaments. Girdles may or may not have a sulcus. If 
a sulcus is present, part of the girdle below the sulcus is smooth; if a 
sulcus is absent, the entire girdle is ornamented. Crowded 
chromatophores are numerous, small, and disc shaped. 

REPRODUCTION 

A single auxospore is formed within a cell. Microspores were observ- 
ed by Schmidt (1923) in Melosira varians. 

OCCURRENCE 

Melosira, a filamentous centric alga, is one of the most ubiquitous of 
the algal genera. It is widely distributed in all types of waters; 
however, some species are indicative of particular environmental con- 
ditions. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 3.4 ■ 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 4 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



34.0 


16.4 


8.4 


10.0 


7.6 


.7 


20.7 


9.0 


2.4 


49,000 


524 


1,296 


378 


100 


72 


2,000 


155 


165 


41.0 


1.43 


1.70 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



85 




Figure 36. -Scanning electronmicrograph of Melosira. 



86 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Naviculaceae 
GENUS NAVICULA Bory, 1822 (fig. 37) 

MORPHOLOGY 

Cells generally are solitary and free floating but may be aggregated 
into irregularly radiating clusters. Cells are symmetrical, elongate, and 
generally attenuated toward the poles. Apices are capitate, rounded, or 
rostrate. Intercalary bands are lacking. The raphe is straight and cen- 
tral, and polar nodules are expanded. Striations are transverse, 
sometimes medially radiate. There are 2 (most commonly) or 4 to 8 
laminate chromatophores. 

REPRODUCTION 

Two approximate cells each form 2 gametes. Union of gametes 
results in 2 auxospores. 

OCCURRENCE 

The genus has a widespread distribution and is found in all types of 
surface waters. Some species are indicative of particular environmen- 
tal conditions (Patrick, 1948, 1973). According to information included 
in this report, Navicula is the second most commonly occurring genus 
in the phytoplankton of the United States. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 3.4 - 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Boyer (1927a), Cleve (1895), and Patrick and Reimer (1966). 



37.0 


15.2 


8.6 


10.0 


7.6 


.7 


20.6 


9.2 


2.4 


49,800 


940 


2,960 


500 


111 


81 


2,000 


205 


256 


41.0 


1.52 


2.02 


4.0 


.2 


.4 



DESCRIPTION OF THE GENERA 



87 




I 



t.. 







* 

:> 






(l 






\ 






P 



Figure 37. - Photomicrograph of Navicula. 



88 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Nitzschiaceae 
GENUS NITZSCHIA Hassall, 1845 (fig. 38) 

MORPHOLOGY 

Cells are solitary and free floating or densely clustered in unbranched 
gelatinous tubes. They are generally elongate and extremely varied in 
outline, having somewhat attenuated poles. Valves are longitudinally 
asymmetrical. Keeled margin of one valve faces unkeeled margin of 
other valve. The raphe lies within the keel and has small central and 
polar nodules. A rapheal fissure has a uniseriate row of conspicuous cir- 
cular pores (carinal dots) opening toward the interior of the cell. Striae 
or punctae are transverse. Two chromatophores on same girdle face 
are axial. 

REPRODUCTION 

Protoplasts of 2 approximate cells each form 2 gametes. Union of 
gametes forms 2 auxospores. 

OCCURRENCE 

The genus has a widespread distribution and is found in all types of 
waters. Some species are indicative of particular environmental condi- 
tions (Patrick, 1948, 1973). According to information included in this 
report, Nitzschia is the most commonly occurring genus in the 
phytoplankton of the United States. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 ■ 

pH 3.4 - 

Dissolved oxygen milligrams per liter .2 ■ 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



37.0 


15.6 


8.8 


10.0 


7.6 


.7 


22.0 


9.1 


2.5 


49,800 


966 


2,930 


500 


115 


81 


2,000 


214 


259 


36.0 


1.54 


2.01 


4.0 


.2 


.4 



DESCRIPTION OF THE GENERA 



89 


















iS 



r- 



Figure 38. - Photomicrograph of Nitzschia. 



90 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Naviculaceae 
GENUS PINNULARIA Ehrenberg, 1840 (fig. 39) 

MORPHOLOGY 

Solitary, free-floating cells are symmetrical, generally straight, and 
have broadly rounded poles. Girdle view is rectangular; axial view is 
generally broad and expanded polarly and medially. Girdles are 
smooth. Intercalary bands are lacking. The raphe is complicated and 
straight or sigmoid. Costae are tubular openings in the valve wall. Two 
longitudinal lines are visible in the costae part of the valve. There are 2 
laminate chromatophores. 

REPRODUCTION 

Two auxospores are formed by the union of 2 gametes from each of 2 
approximate cells. 

OCCURRENCE 

The genus is widely distributed. It generally is indicative of calm or 
slowly moving, slightly acid waters having low mineral content. 
Sometimes Pinnularia is present in abundance in semipermanent or 
permanent pools of soft-water localities (Smith, 1950). 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.5 

pH 3.4 - 8.9 

Dissolved oxygen milligrams per liter 1.3 - 15.2 

Specific conductance micromho 20 -43,400 

Total alkalinity milligrams per liter - 430 

Total hardness do 3 - 1,700 

Total nitrogen do .09- 32.0 

Total phosphorus do .0 - 3.9 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



15.8 


8.2 


7.3 


.9 


8.9 


2.1 


662 


2,060 


91 


83 


153 


213 


1.48 


2.24 


.2 


.4 



DESCRIPTION OF THE GENERA 







91 



Figure 39. -Photomicrograph of Pinnularia. 



92 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Achnanthaceae 
GENUS RHOICOSPHENIA Grunow, 1860 (fig. 40) 

MORPHOLOGY 

Wedge-shaped cells are sessile and attached at the narrower end to a 
more or less branching system of gelatinous stalks affixed to 
macrophytes. Cells are 4-8 /tm in diameter and 12-75 /*m long. The 
hypotheca is concave and contains a median raphe and nodules. The 
epitheca is convex and contains a median pseudoraphe. In girdle view, 
cells are cuneate and curved in the longitudinal axis. Intercalary bands 
are unornamented between striated girdles. Other striations are 
transverse. There are 2 longitudinal septa. A single chromatophore is 
laminate. 

REPRODUCTION 

Conjugating sister cells form a single auxospore. 

OCCURRENCE 

The alga has a widespread distribution. The single species, 
Rhoicosphenia curvata, is found commonly in flowing alkaline waters. 
It is generally intolerant of saline conditions. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 32.5 

pH 5.2 - 9.3 

Dissolved oxygen milligrams per liter 3.4 - 16.6 

Specific conductance micromho 10 -10,000 

Total alkalinity milligrams per liter 1 - 480 

Total hardness do 4 - 1,600 

Total nitroeen__ do .00- 32.0 



;pti' 



Total phosphorus do .0 - 3.1 



12.6 


7.8 


7.8 


.6 


10.0 


2.2 


492 


671 


109 


74 


160 


152 


1.43 


1.91 


.2 


.3 



SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



DESCRIPTION OF THE GENERA 



93 




Figure 40. - Photomicrograph of Rhoicosphenia. 



94 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Centrales 
Family Coscinodiscaceae 
GENUS STEPHANODISCUS Ehrenberg, 1845 (fig. 41) 

MORPHOLOGY 

Solitary, free-floating cells are discoid. Valves are circular, radially 
punctate, and have short marginal spines. Outer areas of punctae are in 
multiseriate rows; each row becomes uniseriate toward the center. 
Small central area is irregularly punctate. Girdles are slightly undulate 
and smooth and lack intercalary bands. There are 1 or 2 irregular or 
numerous discoid chromatophores. 

REPRODUCTION 

A single auxospore is formed within a cell. 

OCCURRENCE 

This is a widely distributed diatom. It is an insignificant component 
of algal communities indicating eutrophic conditions. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.0 

pH 4.6 - 9.4 

Dissolved oxygen milligrams per liter .1 - 16.6 

Specific conductance micromho 10 -10,800 

Total alkalinity milligrams per liter 3 - 470 

Total hardness do 9 - 1,800 

Total nitrogen do .00- 24.0 

Total phosphorus do .0 - 3.1 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Skvortzow (1937). 



16.1 


8.6 


7.8 


.6 


9.3 


2.4 


533 


879 


113 


64 


171 


165 


1.49 


1.89 


.2 


.3 



DESCRIPTION OF THE GENERA 



95 




Figure 41. -Scanning electronmicrograph of Stephanodiscus. 



96 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Surirellaceae 
GENUS SURIRELLA Turpin, 1828 (fig. 42) 

MORPHOLOGY 

Cells generally are solitary and free floating, are linear elliptical or 
ovate in valve view, have broadly rounded to subacute poles, and are 
rectangular naviculoid, cuneate, or sigmoid in girdle view. Girdles are 
smooth. Entire valve face may be in 1 plane, or it may be slightly spiral- 
ly twisted. Each valve margin is keeled and contains a raphe having 
central and polar nodules. Parallel costae are transverse. Fine striae 
extend across valve face and are interrupted by a median longitudinal 
pseudoraphe. One chromatophore is present. 

REPRODUCTION 

Protoplasts from 2 cells lying end to end unite to form an auxospore. 

OCCURRENCE 

The alga has a widespread distribution. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 37.0 

pH 3.7 - 10.0 

Dissolved oxygen milligrams per liter 2.5 - 18.4 

Specific conductance micromho 29 -35,000 

Total alkalinity milligrams per liter - 440 

Total hardness do 6 - 1,800 

Total nitrogen do .01- 41.0 

Total phosphorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Boyer (1927a). 



12.8 


8.5 


7.7 


.6 


9.7 


2.3 


985 


1,910 


137 


83 


260 


275 


2.10 


2.60 


.3 


.4 



DESCRIPTION OF THE GENERA 



97 






* 



•■ 



. 




■r 

i 





Figure 42. -Photomicrograph oiSurirella. 



98 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Fragilariaceae 
GENUS SYNEDRA Ehrenberg, 1830 (fig. 43) 

MORPHOLOGY 

Cells are narrow and generally very elongate. They are solitary or in 
tufted, fan-shaped, or radiating colonies. They are free floating or 
epiphytic, sessile, or contained in a gelatinous stalk. Cells are linear to 
lanceolate, generally straight but sometimes slightly curved. Poles may 
be attentuated and sometimes capitate. Transverse striae are lateral to 
a conspicuous narrow pseudoraphe. The central area may be smooth or 
striated. The two chromatophores are discoid. 

REPRODUCTION 

Either 1 or 2 auxospores may be formed within a cell. A "regenera- 
tion" cell, which increases the size of the cell, has been observed by Ge- 
meinhardt (1926). 

OCCURRENCE 

Synedra is widely distributed and is found in all types of waters. The 
commonly occurring species generally occur in circumneutral water of 
moderate to high conductivity, including brackish water. The genus is 
generally indicative of mesotrophic to eutrophic conditions. It is found 
in the euplankton, tychoplankton, and periphyton. 

ENVIRONMENTAL CONDITIONS 



Range 

Temperature degrees Celsius 0.0 - 37.0 

pH 3.7 - 10.0 

Dissolved oxygen milligrams per liter .2 - 20.7 

Specific conductance micromho 10 -49,800 

Total alkalinity milligrams per liter 3 - 491 

Total hardness do 2 - 1,900 

Total nitrogen do .00- 41.0 

Total phosphorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 





Standard 


Mean 


deviation 


14.5 


8.8 


7.6 


.7 


9.4 


2.4 


671 


2.050 


105 


79 


180 


223 


1.38 


1.81 


.2 


.3 



DESCRIPTION OF THE GENERA 99 

(jgfBl , "" 1 " mm huh i nun nil i ii i iiiiiiiiiiiiiii.nl I ill lllliiunr i mn i nimn 11 1 it 1 1 1 m i n ri ii i dm i i ii j ii h t i i, u l ■■ 1 11 miM iiiii n ii i 'i'i " "" i 

H " 111 " 1 """ 1 i i i ii i ii i iii mh i mi ii ll'llll'Ml.inliilmiiiiiii '"■"in ■ ■ ■■iiiwiilllllllllllil""""" 1 ' J 

FIGURE 43. - Drawing of Synedra. 



100 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Chrysophyta 
Class Bacillariophyceae 
Order Pennales 
Family Tabellariaceae 
GENUS TABELLARIA Ehrenberg, 1840 (fig. 44) 

MORPHOLOGY 

Cells generally are joined into zigzag chains but sometimes into 
stellate colonies. They are free floating. Valves have numerous inter- 
calary bands between the girdles. Between the girdles and intercalary 
bands are longitudinal septa penetrating to the center of the cell. 
Valves are elongate and have an evident, medial inflation. They are 
slightly inflated at the poles. There is a narrow pseudoraphe that has 
lateral, transverse striae. Chromatophores are numerous small discs. 

REPRODUCTION 

Either 1 (Geitler, 1927) or 2 (Schiitt, 1896) auxospores may form 
within a single cell. 

OCCURRENCE 

The genus is of widespread distribution in the euplankton. The most 
common species, Tabellaria fenestrata, is indicative of mesotrophic to 
eutrophic conditions. The genus generally occurs in circumneutral, 
shallow waters. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 3.9 

Dissolved oxygen milligrams per liter 1.2 

Specific conductance micromho 16 

Total alkalinity milligrams per liter 3 

Total hardness do 5 

Total nitrogen do .01 

Total phosphorus do .0 

SPECIES INFORMATION 

Refer to Boyer (1927a) and Patrick and Reimer (1966). 



- 31.0 


12.4 


8.1 


8.9 


7.3 


.7 


- 16.7 


10.0 


2.4 


-6,860 


221 


391 


- 320 


64 


58 


-1,500 


87 


121 


- 11.0 


.87 


1.08 


2.7 


.1 


.2 



DESCRIPTION OF THE GENERA 



101 




Figure 44. -Photomicrograph of Tabellaria. 



102 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Pyrrophyta 
Class Dinophyceae 
Order Peridiniales 
Family Glenodiniaceae 
GENUS GLENODINIUM Stein, 1883 (fig. 45) 

MORPHOLOGY 

Solitary, motile cells are asymmetrically globose but may be slightly 
dorsoventrally flattened. The cell is surrounded by a definite number of 
plates arranged in a specific manner. Cell wall is divided near the 
center into an apical epitheca and an antapical hypotheca. Epitheca has 
2-9 apical, 0-4 anterior intercalary, and 6-12 precingular plates; 
hypotheca has 5-12 postcingular, 0-2 posterior intercalary, and 1-2 an- 
tapical plates. A longitudinal sulcus extends from the girdle into the 
hypotheca. There are 2 flagella. A prominent eyespot may be present. 
Numerous chromatophores are brown. 

REPRODUCTION 

Reproduction is isogamous by the union of gymnodinoid gametes. 
Each zygote forms 4 zoospores. 

OCCURRENCE 

The genus is generally found in the tychoplankton; however, it can 
occur in the euplankton. It seems to prefer soft- water conditions. 

ENVIRONMENTAL .CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius__ 0.0 - 34.0 

pH 4.6 - 9.2 

Dissolved oxygen milligrams per liter .1 - 22.0 

Specific conductance micromho 11 -42,100 

Total alkalinity milligrams per liter - 477 

Total hardness do 6 - 1,700 

Total nitrogen do .00- 11.0 

Total phosphorus do .0 - 3.2 

SPECIES INFORMATION 

Refer to Schiller (1933) and Prescott (1962). 



17.5 


9.6 


7.6 


.7 


8.6 


3.1 


,400 


4,570 


120 


80 


219 


248 


1.26 


1.17 


.1 


.2 



DESCRIPTION OF THE GENERA 



103 








) 






Figure 45. -Photomicrograph of Glenodinium. 



1 04 ALGAE IN PH YTOPL ANKTON OF THE UNITED STATE S 

Division Pyrrophyta 
Class Dinophyceae 
Order Peridiniales 
Family Peridiniaceae 
GENUS PERIDINIUM Ehrenberg, 1830; emend., Stein, 1883 

(fig. 46) 

MORPHOLOGY 

Solitary, motile cells are spherical, ovoid, or angular and may or may 
not have short apical and antapical horns. The cell is surrounded by a 
definite number of plates arranged in a specific manner. Cell wall is 
divided near the center into an apical epitheca and an antapical 
hypotheca. Epitheca has 4 apical, 2-3 anterior intercalary, and 7 prec- 
ingular plates; hypotheca has 5 postcingular and 2 antapical plates. A 
longitudinal sulcus extends from the girdle into the hypotheca. There 
are 2 flagella. A prominent eyespot may be present. Numerous 
chromatophores are brown. 

REPRODUCTION 

Aplanospores are formed by division of the protoplast. 

OCCURRENCE 

The alga is of widespread distribution in the euplankton and 
tychoplankton. 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.0 

pH 4.6 - 9.6 

Dissolved oxygen milligrams per liter .8 - 18.7 

Specific conductance micromho 26 -30,000 

Total alkalinity milligrams per liter 3 - 477 

Total hardness do 5 - 2,000 

Total nitrogen do .05- 13.0 

Total phosphorus do .0 - 2.2 

SPECIES INFORMATION 

Refer to Lefevre (1932) and Prescott (1962). 



18.6 


9.2 


7.6 


.7 


8.5 


2.8 


881 


2,480 


113 


85 


197 


241 


1.10 


1.10 


.1 


.2 



DESCRIPTION OF THE GENERA 



105 




Figure 46. -Drawing of Peridinium. 



106 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cryptophyta 
Class Cryptophyceae 
Order Cryptomonidales 
Family Cryptochrysidaceae 
GENUS CHROOMONAS Hansgrirg, 1892 (fig. 47) 

MORPHOLOGY 

Solitary, motile cells are compressed. The anterior end is truncated, 
and the posterior end is rounded. A longitudinal furrow is at the 
anterior end near the point of insertion of 2 unequal flagella. An 
eyespot and granules may be present. The single laminate 
chromatophore is blue green. 

REPRODUCTION 

Longitudinal division of the protoplast results in the formation of 2 
daughter cells. Rosenberg (1944) observed a palmella stage. 

OCCURRENCE 

The alga is common in shallow waters and among algal masses and 
decaying vegetation (Prescott, 1962). 

ENVIRONMENTAL CONDITIONS 



Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 33.5 

pH 4.3 - 8.9 

Dissolved oxygen milligrams per liter .1 - 17.0 

Specific conductance micromho 21 -47,800 

Total alkalinity milligrams per liter - 477 

Total hardness do 4 - 1,700 

Total nitrogen do .01- 24.0 

Total phosphorus do .0 - 3.5 

SPECIES INFORMATION 

Refer to Lackey (1939), Pascher (1913), and Prescott (1962). 



16.5 


9.0 


7.7 


.7 


8.9 


2.9 


1,110 


4,030 


128 


82 


209 


198 


1.25 


1.73 


.1 


.2 



DESCRIPTION OF THE GENERA 



107 




Figure 47. - Drawing of Chroomonas. 



108 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cryptophyta 
Class Cryptophyceae 
Order Cryptomonidales 
Family Cryptomonodaceae 
GENUS CRYPTOMONAS Ehrenberg, 1831 (fig. 48) 

MORPHOLOGY 

Solitary, free-swimming cells are compressed, somewhat elliptical, 
and broadly rounded to truncate at the anterior end. Two unequal 
flagella are inserted into an evident gullet, which may be lined with 
granular trichoblasts. A contractile vacuole is next to the gullet. The 1 
to 2 large chromatophores are yellow to olive green but are sometimes 
red. 

REPRODUCTION 

A mucilage surrounds an immobile stage prior to longitudinal divi- 
sion into 2 daughter cells. 

OCCURRENCE 

Cryptomonas is found in the euplankton and tychoplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 34.0 

pH 4.1 - 9.7 

Dissolved oxygen milligrams per liter .2 - 22.0 

Specific conductance micromho 20 -41,000 

Total alkalinity milligrams per liter - 477 

Total hardness do 3 - 2,000 

Total nitrogen do .01- 19.0 

Total phosphorus do .0 - 3.9 

SPECIES INFORMATION 

Refer to Pascher (1913) and Prescott (1962). 



16.3 


8.8 


7.8 


.6 


9.0 


2.9 


862 


1,910 


144 


78 


248 


228 


1.52 


1.59 


.2 


.3 



DESCRIPTION OF THE GENERA 



109 



•^•wjjs 






V-:? 






.■■••|.,r1 1 



Figure 48. -Drawing of Cryptomonas. 



110 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Chyroococcales 
Family Chroococcaceae 
GENUS AGMENELLUM Drouet and Daily, 1956 (fig. 49) 

Generic Synonym. -Merismopedia Meyen, 1839 

MORPHOLOGY 

Cells are spherical or almost hemispherical when dividing. They are 
contained in free-floating, multicelled colonies. Cells, 3-6 ^m wide, are 
regularly arranged in parallel vertical and transverse rows. The colony 
is 1 cell in thickness. The gelatinous matrix is homogeneous and col- 
orless. 

REPRODUCTION 

Reproduction is by cell division and colony fragmentation. 

OCCURRENCE 

Agmenellum is widely distributed and generally is indicative of soft- 
water and acidic conditions. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius__ 0.0 - 36.0 22.5 7.2 

pH 5.6 - 9.4 7.7 .6 

Dissolved oxygen milligrams per liter .1 - 20.6 8.2 2.4 

Specific conductance micromho__ 26 -39,500 1,190 2,720 

Total alkalinity milligrams per liter 1 - 450 120 78 

Total hardness do 4 - 2,000 241 272 

Total nitrogen do .01- 21.0 1.52 1.63 

Total phosphorus do .0 - 3.1 .2 .3 

SPECIES INFORMATION 

Refer to Thompson (1938), Geitler (1930), and Prescott (1962). 



DESCRIPTION OF THE GENERA 



111 




















& 



!*S 



I 



•k 



Figure 49. - Photomicrograph of Agmenellum. 



112 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Nostocaceae 
GENUS ANABAENA Bory, 1822 (fig. 50) 

MORPHOLOGY 

Cells are spherical to barrel shaped, are homogeneous or granulose, 
and sometimes contain pseudovacuoles. They are united into free- 
floating, beadlike trichomes that are solitary or aggregated. Trichomes 
are cylindrical or slightly attentuated at the apices. They may be 
straight, circinate, or spirally or irregularly twisted. Intercalary 
heterocysts are spherical. Akinetes are variously shaped. 

REPRODUCTION 

Reproduction is by heterocysts and akinetes. 

OCCURRENCE 

The genus is found commonly in the euplankton and tychoplankton of 
hard water or eutrophic water during periods of high temperature. It is 
a frequent component of algal blooms and is indicative of hard water 
having a high nutrient content when occurring with Aphanizomenon or 
Anacystis. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 37.0 

pH 4.4 - 9.6 

Dissolved oxygen milligrams per liter .4 - 19.0 

Specific conductance micromho 12 -30,000 

Total alkalinity milligrams per liter - 371 

Total hardness do 5 - 1,600 

Total nitrogen., do .00- 18.0 

Total phospnorus do .0 - 3.5 

SPECIES INFORMATION 

Refer to Geitler (1932) and Prescott (1962). 



20.1 


7.7 


7.6 


.7 


8.3 


2.3 


:i7 


1,650 


102 


73 


173 


195 


1.34 


1.64 


.2 


.4 



DESCRIPTION OF THE GENERA 



113 



A 






^-m 





Figure 50. -Photomicrograph of Anabaena. 



114 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Chroococcales 
Family Chroococcaceae 
GENUS ANACYSTIS Meneghini, 1837; emend., Daily, 1942 
(fig. 51) 

Generic Synonyms. -Microcystis Kiitzing, 1833; Polycystis Kiitzing, 1849; Clathrocystis 
Henfrey, 1956. 

MORPHOLOGY 

Cells are spherical or almost hemispherical when dividing and range 
from 2 to 10 fim in diameter. They are irregularly and densely ag- 
gregated in a free-floating, colonial, gelatinous matrix. Colonies are 
amorphous. 

REPRODUCTION 

Reproduction is by cell division and colony fragmentation. 

OCCURRENCE 

Anacystis is very common in hard water or eutrophic water during 
periods of high temperature. It is a frequent component of algal blooms 
and is notorious as a spoiler of water for domestic uses, swimming, and 
other forms of recreation. The alga often causes death offish in heavily 
infested lakes. It is indicative of hard water with high nutrient content 
when occurring in large numbers with Aphanizomenon or Anabaena. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 3.7 • 

Dissolved oxygen milligrams per liter .1 - 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 2 

Total nitrogen do .00- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Daily (1942), Elenkin (1924), Drouetand Daily (1939), Teil- 
ing (1946), and Prescott (1962). 



36.0 


19.1 


8.1 


10.0 


7.6 


.7 


20.7 


8.5 


2.4 


48,000 


866 


2,180 


500 


113 


81 


2,000 


207 


246 


41.0 


1.46 


1.70 


3.9 


.2 


.3 



DESCRIPTION OF THE GENERA 



115 




; 



Figure 51. -Photomicrograph of Anacystis. 



116 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Nostocaceae 
GENUS APHANIZOMENON Morren, 1838 (fig. 52) 

MORPHOLOGY 

Cells are cylindrical or barrel shaped and rarely exceed 5 /*m in 
diameter. They are united into straight or slightly curved trichomes, 
which are laterally agglutinated by indistinct sheaths. Trichomes are 
free floating. Intercalary heterocysts are cylindrical. Akinetes are 
cylindrical. 

REPRODUCTION 

Reproduction is by heterocysts and akinetes. 

OCCURRENCE 

The single species, Aphanizomenon flos-aquae, is so consistently 
related to hard water that it may be used as an index organism for high 
pH and high contents of nitrogen, phosphorus, and carbonate. It is a 
notorious component of algal blooms and occurs commonly with Ana- 
baena and Anacystis. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 36.0 

pH 4.6 - 9.6 

Dissolved oxygen milligrams per liter 2.0 - 18.7 

Specific conductance micromho 11 -42,000 

Total alkalinity milligrams per liter 3 - 311 

Total hardness do 6 - 1,700 

Total nitrogen do .05- 24.0 

Total phosphorus do .0- 3.1 

SPECIES INFORMATION 

Refer to Smith (1920) and Prescott (1962). 



19.2 


8.3 


7.7 


.6 


8.4 


2.3 


877 


2,870 


109 


68 


193 


203 


1.61 


2.12 


.2 


.3 



DESCRIPTION OF THE GENERA 



117 







Figure 52. -Photomicrograph of Aphanizomenon. 



118 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormongonales 
Family Nostocaceae 
GENUS CYLINDROSPERMUM Kiitzing, 1843 (fig. 53) 

MORPHOLOGY 

Cells are cylindrical and united into short, straight trichomes. Cells 
range from 2 to 5 /*m in diameter. Trichomes are free floating or found 
on moist soil. Heterocysts are cylindrical and always terminal. 
Akinetes are contiguous to heterocysts. 

REPRODUCTION 

Reproduction is by heterocysts and akinetes. 

OCCURRENCE 

The genus commonly occurs in the tychoplankton and periphyton. 
The more common species occur in hard-water, alkaline conditions. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 1.5 - 

pH 5.9 - 

Dissolved oxygen milligrams per liter 1.7 - 

Specific conductance micromho 35 

Total alkalinity milligrams per liter 3 

Total hardness do 6 

Total nitrogen do .10- 

Total phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Geitler (1932) and Prescott (1962). 



34.0 


24.2 


6.3 


9.1 


7.6 


.7 


20.0 


7.6 


2.3 


12,000 


999 


1.47H 


430 


107 


73 


1,600 


235 


239 


18.0 


1.39 


1.80 


2.7 


.2 


.3 



DESCRIPTION OF THE GENERA 



119 




Figure 53. -Drawing of Cylindrospermum. 



120 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Chroococcales 
Family Chroococcaceae 
GENUS GOMPHOSPHAERIA Kutzing, 1836 (fig. 54) 

MORPHOLOGY 

Cells are pyriform, obovoid, or cylindrical; when dividing, they are 
heart shaped or obcuniform. Cells are peripherally distributed in a 
single layer with long axes radiating in a globous colony. Each cell has 
a distinct individual sheath, and each has a gelatinous projection at its 
base. Projections from all cells are joined toward the center of the col- 
ony. The colonial matrix is gelatinous. 

REPRODUCTION 

Reproduction is bv cell division and colony fragmentation. 

OCCURRENCE 

The genus is of widespread distribution in the euplankton and 
tychoplankton of both soft-water and hard-water bodies. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 

pH 4.9 

Dissolved oxygen milligrams per liter .4 • 

Specific conductance micromho 32 

Total alkalinity milligrams per liter 4 

Total hardness do 9 

Total nitrogen do .01- 

Tota! phosphorus do .0 - 

SPECIES INFORMATION 

Refer to Smith (1920) and Prescott (1962). 



33.5 


19.6 


8.2 


9.2 


7.7 


.6 


18.4 


8.6 


2.5 


9,230 


556 


796 


426 


111 


73 


1,400 


173 


158 


6.7 


1.24 


.99 


3.5 


.1 


.2 



DESCRIPTION OF THE GENERA 



121 







Figure 54. -Drawing of Gomphosphaeria. 



122 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Oscillatoriaceae 
GENUS LYNGBYA Agardh, 1824 (fig. 55) 

MORPHOLOGY 

Cells are discoidal and adjoined at the flat faces into long trichomes. 
Trichomes are unbranched, uniseriate, the same diameter from base to 
apex, and contained in firm, conspicuous sheaths. Filaments are 
straight, curved, or twisted and may be solitary or densely intertwined 
into floccose masses. They may be free floating or epiphytic. 
Heterocysts and akinetes are lacking. 

REPRODUCTION 

Reproduction is by hormogonia. 

OCCURENCE 

The genus is found commonly in eutrophic waters, and it is generally 
indicative of hard water. It can occur in great numbers in eutrophic 
lakes, where it remains distributed through the water column. It is 
found in both the euplankton and tychoplankton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 - 34.5 

pH 4.1 - 9.2 

Dissolved oxygen milligrams per liter .1 - 20.6 

Specific conductance micromho 24 -48,000 

Total alkalinity milligrams per liter - 478 

Total hardness do 3 - 2,000 

Total nitrogen do .01- 18.0 

Total phosphorus do .0 - 4.0 

SPECIES INFORMATION 

Refer to Gomont (1892a), Geitler (1932), and Prescott (1962). 



16.7 


9.9 


7.5 


.7 


8.7 


2.8 


952 


2,440 


113 


83 


216 


256 


1.58 


1.82 


.2 


.4 



DESCRIPTION OF THE GENERA 



123 




Figure 55. -Photomicrograph of Lyngby a. 



124 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Oscillatoriaceae 
GENUS OSCILLATORIA Vaucher, 1803 (fig. 56) 

MORPHOLOGY 

Cells are discoidal and adjoined at the flat surfaces into long 
trichomes. Trichomes are unbranched, uniseriate, and sometimes 
apically attenuated. Sheaths are not evident. Filaments are straight, 
curved, or contorted and may be solitary or in floccose masses. They 
are free floating or epiphytic. Heterocysts and akinetes are lacking. 

REPRODUCTION 

Reproduction is by hormogonia. 

OCCURRENCE 

Oscillatoria is one of the most ubiquitous of the algal genera. It is 
widely distributed in all types of waters and is found commonly in the 
euplankton, tychoplankton, and periphyton. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 3.4 

Dissolved oxygen milligrams per liter .1 

Specific conductance micromho 10 

Total alkalinity milligrams per liter 

Total hardness do 3 

Total nitrogen do .00 

Total phosphorus do : .0 

SPECIES INFORMATION 

Refer to Gomont (1892a, b) and Prescott (1962). 



36.0 


16.9 


9.3 


9.8 


7.6 


.7 


22.0 


8.8 


2.7 


48,000 


923 


2,210 


500 


119 


81 


2,000 


223 


257 


28.0 


1.68 


2.07 


3.9 


.2 


.4 



DESCRIPTION OF THE GENERA 



125 




Figure 56. -Photomicrograph of Oscillatoria. 



126 ALGAE IN PHYTOPT.ANKTON OF THE UNITED STATES 



Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Oscillatoriaceae 
GENUS PHORMIDIUM Kutzing, 1843 (fig. 57) 

MORPHOLOGY 

Cells are discoidal and adjoined at the flat surfaces into trichomes. 
Trichomes are unbranched, cylindrical, and enclosed by watery 
gelatinous sheaths, which are partially or wholly confluent. Apices are 
varied, sometimes capitate, often having calyptra. The plant mass is 
aquatic or subaerial; it often forms an extensive stratum. 

REPRODUCTION 

Reproduction is by hormogonia. 

OCCURRENCE 

The genus is found primarily on moist rocks or damp soil (Smith, 
1950); however, it is commonly found in the euplankton, 
tychoplankton, and periphyton. It occurs most commonly in hard 
water. 

ENVIRONMENTAL CONDITIONS 



Range 

Temperature degrees Celsius 0.0 - 32.5 

pH 4.8 - 8.8 

Dissolved oxygen milligrams per liter 1.2 - 13.3 

Specific conductance micromho 30 -48,000 

Total alkalinity milligrams per liter - 363 

Total hardness do 7 - 1,200 

Total nitrogen do .02- 13.0 

Total phosphorus do .0 - 3.3 

SPECIES INFORMATION 

Refer to Gomont (1892a, b), Geitler (1932), and Prescott (1962). 





Standard 


Mean 


deviation 


20.4 


8.5 


7.6 


.6 


7.7 


2.5 


999 


4,080 


114 


75 


204 


216 


1.50 


1.93 


.2 


.4 



DESCRIPTION OF THE GENERA 



127 







Figure 57. -Drawing of Phxyrmidium. 



128 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Division Cyanophyta 
Class Cyanophyceae 
Order Hormogonales 
Family Rivulariaceae 
GENUS RAPHIDIOPSIS Fritsch and Rich, 1929 (fig. 58) 

MORPHOLOGY 

Cells are cylindrical and about 4.5 yim in diameter. They are 1.5-2 
times as long as wide. The solitary, free-floating trichomes are relative- 
ly short. The sheath is absent. Both poles of a trichome may be tapered, 
or one pole may be tapered and the other, broadly rounded. Numerous 
pseudovacuoles may be present. Akinetes are barrel shaped and are 
located in the middle of the trichome. 

REPRODUCTION 

The trichome breaks transversely into equal halves. Akinetes may be 
found midway in the trichome. 

OCCURRENCE 

The trichomes of the genus are free floating. 

ENVIRONMENTAL CONDITIONS 

Standard 
Range Mean deviation 

Temperature degrees Celsius 0.0 

pH 4.9 

Dissolved oxygen milligrams per liter .1 

Specific conductance micromho 20 

Total alkalinity milligrams per liter 1 

Total hardness do 4 

Total nitrogen do .06 

Total phospTiorus do .0 

SPECIES INFORMATION 

Refer to Fritsch and Rich (1929) and Daily (1945). 



36.0 


19.7 


8.7 


9.1 


7.6 


.7 


15.0 


8.1 


2.5 


-48,000 


783 


2,810 


- 483 


105 


83 


- 1,500 


179 


200 


i- 9.8 


1.43 


1.42 


3.5 


.2 


.3 



DESCRIPTION OF THE GENERA 



129 




Figure 58. -Drawing of Raphidiopsis. 



130 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

GLOSSARY 

[adj, adjective; n, noun; v, verb] 

Acicular (adj). Slenderly needle shaped. 

Adiametric (adj). Having unequal diameters. 

Agglutinate (adj). Adherent; sticking together. 

Aggregate (adj). Massed together. 

Akinete (n). A nonmotile spore, formed directly from a vegetative cell. 

Alga, algae (n), algal (adj). A group of plants, mostly aquatic, single celled, colonial, or 

multicelled, containing chlorophyll and lacking roots, stems, and leaves. 
Amorphous (adj). Lacking a definite shape. 
Anapex (n), anapical (adj). The bottom or end opposite the apex. 
Anisogamy (n), anisogamous (adj). The sexual union of two flagellated or 

nonflagellated gametes of unequal sizes. 
Anterior (adj). At or toward the front. 
Antherozoid (n). A male gamete. 
Apex (n), apical (adj). The top or anterior end. 
Aplanospore (n). A nonmotile spore formed from all or part of the protoplast of a 

vegetative cell and having a wall distinctly different from that of the parent cell. 
Apposed (adj). Paired; opposite but in a definite relation to one another. 
Arcuate (adj). Moderately curved like a bow. 
Asymmetrical (adj). Not symmetrical. 
Attenuated (adj). Tapering at the end. 
Autospore (n). An aplanospore having the same shape as the vegetative cell from which 

it was formed. 
Auxospore (n). A spore formed by asexual metamorphosis of the protoplast of one cell 

or resulting from the sexual fusion of two protoplasts or nuclei; occurs only in diatoms. 
Biflagellate (adj). Having two flagella. 
Bifurcate (adj). Divided into two parts or branches. 
Bipartition (adj). Divided into two parts. 
Calyptra (n). A hood- or cap-shaped covering, sometimes occurring on apical cells of 

filaments. 
Campanulate (adj). Bell shaped. 
Capitate (adj). Having a knoblike end. 
Chloroplast (n). A body in the cell containing chlorophyll as the dominant pigment; see 

chromatophore. 
Chromatophore (n). A body in the cell containing the pigments; see chloroplast. 
Circinate (adj). Rolled inward from the apex. 
Citriform (adj). Lemon shaped. 
Clevate (adj). Club shaped. 
Coenobium, coenobia (n). A colony in which a definite number of cells are arranged in a 

specific way. 
Coenocyte (n), coenocytic (adj). A multinucleate vegetative cell or nonseptate thallus. 
Colony (n), colonial (adj). A group of individuals joined together by a common sheath or 

gelatinous material; a group of cells forming a filament or trichome. 
Concentric (adj). Having a common center. 
Conical (adj). Cone shaped. 

Conjugation (n), conjugate (v). The union of gametes. 
Contractile (adj). Having the ability to contract or expand. 
Costa, costae (n), costate (adj). A rib or ribbed structure. 
Cuneate (adj). Wedge shaped. 

Dichotomous (adj). Divided or branched into two parts; branched. 
Diffuse (adj). Generalized; not localized. 



GLOSSARY 131 



Discoid (adj). Disc shaped. 

Epitheca, epithecae (n). The larger or epivalve of a diatom cell; part of the wall of a 

dinoflagellate, anterior to the transverse furrow. 
Euplankton (n). True plankton. 

Eyespot (n). A small pigmented photosensitive body in certain flagellated algal cells. 
Fascicle (n), fasciculate (adj). A bundle or cluster. 
Filament (n), filamentous (adj). A linear arrangement of cells. 
Flagellum, flagella (n), flagellate (adj). A fine long threadlike structure having 

lashing or undulating movement, projecting from a cell; it is used for locomotion. 
Frustule (n). A diatom cell; the silicified wall of the diatom cell. 
Furcate (adj). Forked. 
Fusiform (adj). Spindle shaped. 
Gamete (n), gametic (adj). A sex cell. 

Gelatinous (adj). Having a jellylike or mucilagelike texture or appearance. 
Gibbose (adj). Swollen on one side. 

Girdle (n). A ring or band connecting two valves in diatoms; a transverse groove. 
Globose (adj). Ball shaped or nearly so. 

Granulate, granulose (adj). Composed of or appearing to be covered with granules. 
Gullet (n). An anterior opening of flagellates. 
Heterocyst (n). A metamorphosed vegetative cell in diatoms; sometimes forms en- 

dospores or a filament. 
Heterothallus (n), heterothallic (adj). A species in which gametes unite only if arising 

from different plants. 
Homothallus (n), homothallic (adj). A species in which gametes unite only if arising 

within the same plant. 
Hormogonium, hormogonia (n). A short, distinct section of a trichome that produces a 

new plant vegetatively. 
Hyaline (adj). Colorless and transparent. 
Hypotheca, hypothecae (n). The small or hypovalve of a diatom cell; part of the wall of a 

dinoflagellate, posterior to the transverse furrow. 
Inflated (adj). Swollen. 

Intercalary (adj). Between or inserted between cells. 
Isodiametric (adj). Having equal diameters. 
Isogamy (n), isogamous (adj). Sexual union of two flagellated or nonflagellated 

gametes of equal size. 
Keel (n). A projecting ridge. 

Laminate (adj). Consisting of or shaped like plates. 
Lanceolate (adj). Lance shaped. 
Linear (adj.). Straight; narrow and long. 
Lorica (n). A firm covering that is not connected to the protoplast and contains an 

anterior opening. 
Lunate (adj). Crescent shaped. 
Macrophyte (n). Large plants that can be seen without magnification; includes mosses 

and seed plants. 
Mucilage (n). A thick, watery substance. 
Multiseriate (adj). Occurring in several rows. 
Naviculoid (adj). Boat shaped. 
Nodule (n). A small knob. 
Obcuniform (adj). Inversely wedge shaped. 

Obovoid (adj). Inversely ovoid, with the broader end anterior or outermost. 
Oogamy (n). oogamous (adj). Sexual union of a small motile male gamete (sperm) with a 

large nonmotile female gamete (egg). 



132 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Ovate, ovoid (adj). Oval; egg shaped. 

Palmella (n), palmelloid (adj). A genus of green algae, whose spherical cells are united 

by their mucilage coats into indefinite mucilaginous masses. 
Parietal (adj). Pertaining to or near the wall. 
Periphery (n). The outer boundary or edge. 
Periphyton (n), periphytic (adj). The community of micro-organisms that are attached 

to or live upon submerged surfaces. 
Phytoplankton (n), phytoplanktonic (adj). The plant part of the plankton. 
Plankton (n), planktonic (adj). The community of suspended or floating organisms that 

drift passively with water currents. 
Polar (adj). Pertaining to the pole or end. 
Polyhedral (adj). Having numerous faces or planes. 
Postcingular (adj). Referring to position of plates adjacent to the girdle of the 

hypotheca of certain dinoflagellates. 
Precingular (adj). Referring to position of plates adjacent to the girdle in the epitheca of 

certain dinoflagellates. 
Protoplast (n). The living contents of a cell; the nucleus, cytoplasm, and plasma mem- 
brane that constitute a living unit. 
Pseudoraphe (n). The axial field of the valves of pennate diatoms lacking a longitudinal 

cleft or raphe. 
Pseudovacuole (n). A false vacuole; a pocket of gas or fluid within the protoplast. 
Puncta, punctae (n), punctate (adj). A tiny spot, dot, point, or depression. 
Pyramidal (adj). Pyramid shaped. 
Pyriform (adj). Pear shaped. 
Quadrate (adj). Square; arranged in fours. 
Quadriflagellate (adj). Having four flagella. 

Radial (adj). Radiating from a common center or point; pertaining to the radius. 
Raphe (n), rapheal (adj). A longitudinal cleft in the axial field of certain pennate 

diatoms. 
Recurved (adj). Curved; bent down. 
Reniform (adj). Kidney shaped. 
Reticulate (adj). Like a network. 
Rhombic (adj). Resembling a rhomboid. 
Rostrate (adj). Having a beak. 

Semicell (n). One-half of a vegetative cell of a desmid. 
Sessile (adj). Pertaining to an organism that is attached to an object. 
Seta, setae (n). A slender, more or less rigid bristle, a short hair. 
Sheath (n). A covering, envelope, or tube that is composed of mucilage. 
Sigmoid (adj). S-shaped. 
Solitary (adj). Single; alone. 
Spherical (adj). Sphere shaped; globular. 
Spicate (adj). Having spikes or spines. 
Spine (n). A stiff, pointed process. 

Stalk (n). A supporting structure, generally mucilage, affixed to a substrate. 
Statospore (n). An asexually formed spore having thick silicified walls composed of two 

overlapping halves. 
Stauros (n). A thickness and transversely expanded central nodule interrupting the 

raphe of certain diatoms. 
Stellate (adj). Star shaped. 

Stria, striae (n), striate (adj). Long delicate markings on the frustules of diatoms. 
Subacute (adj). Almost pointed. 
Subcylindrical (adj). Almost cylindrical in shape. 



SELECTED REFERENCES 133 

Subelliptical (adj). Almost elliptical in shape. 

Subpolar (adj). Near the pole, end, or apex. 

Subspherical (adj). Almost spherical in shape. 

Sulcus (n). A groove or furrow. 

Suture (n). The seam or ridge formed by apposed margins. 

Tabular (adj). Table shaped; having a flat surface. 

Terminal (adj). At or near the end. 

Trichome (n). A uniseriate row of cells in a filament; a filament exclusive of a gelatinous 

sheath. 
Truncate (adj). Terminating abruptly by a nearly straight edge or surface. 
Tvchoplankton (n). Organisms in the plankton, which were scoured from the bottom. 
Undulate (adj). Wavy. 
Uniflagellate (adj). Having one flagellum. 
Uniseriate (adj). In a single row. 

Vacuole (n). An area in the protoplasm containing cell fluid and sometimes granules. 
Valve (n). The silicified parts of a diatom cell. 
Verrucose (adj). Covered with wartlike elevations. 
Vesicule (n). A bladderlike structure. 
Zoospore (n). A flagellated, asexually formed spore. 
Zygote (n), zygotic (adj). A cell resulting from the union of two gametes or gametic 

nuclei. 

SELECTED REFERENCES 

Agardh, C. A., 1824, Systema algarum: Lund, v. 1, 312 p. 

Ahlstrom, E. H., 1937, Studies on variability in the genus Dinobryon (Mastigophora): 

Transactions of the American Microscopical Society, v. 56, p. 139-159. 
Ahlstrom, E. H., and Tiffany, L. H., 1934, The algal genus Tetrastrum: American 

Journal of Botany, v. 21, p. 499-507. 
Bigeard, E., 1933, Les Pediastrum d'Europe. Etude biologique et systematique: Trav. 

Lab. Bot., Univ. Cathol. Angers, no. 5, p. 1-192. 
Bold, H. C, and Wynne, M. J., 1978, Introduction to the algae -Structure and reproduc- 
tion: Englewood Cliffs, N.J., Prentice-Hall, Inc., 706 p. 
Bory (de St. Vincent), J. B., 1822-1831, in Dictionnaire d'histoire naturelle: Paris. 
Boyer, C. S., 1927a, Synopsis of the North American Dictomaceae, Part 1: Proceedings 

of the Academy of Natural Sciences of Philadelphia, v. 78, supplement, p. 1-228. 
1927b, Synopsis of the North American Diatomaceae, Part 2: Proceedings of the 

Academy of Natural Sciences of Philadelphia, v. 78, supplement, p. 229-583. 
Brunnthaler, J., 1915, Protococcales, in Pascher, A., Die Susswasserflora Deutschlands, 

Osterreichs, und der Schweiz, Heft 5, Chlorophyceae 2: Jena, p. 52-205. 
Chapman, V. J., 1962, The algae: New York, Macmillan, 472 p. 
Chodat, R., 1894, Materiaux pour servir a l'histoire des Protococcoidees: Bull. Herb. 

Boiss., v. 2, p. 585-616. 
1895, Uber die Entwickelung der Eremosphaera viridis de By: Bot. Zeitg., v. 53, 

p. 137-142. 
1897, Recherches sur les algues pelagiques de quelques lacs suisses et francais: 

Bull. Herb. Boiss., v. 5, 289-314. 
-1926, Scenedesmus. Etude de genetique, de systematique experimentale et 



d'hydrobiology: Revue d'Hydrologie, v. 3, p. 71-258. 
Cleve, P. T., 1894, Synopsis of the naviculoid diatoms: Kungliga Svenska Veten- 
skapsakademiens Handlingar, v. 26, p. 1-194. 



134 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Cleve, P. T., 1895, Synopsis of the naviculoid diatoms: Kungliga Svenska Vetenskap- 

sakademiens Handlingar, v. 27, no. 2, p. 1-219. 
Collins, F. S., 1909, The green algae of North America: Boston, Mass., Tufts College 

Studies, Scientific Series, no. 2, p. 79-480. 
Corda, A. J. C, 1835-1839, Observations sur les animalicules microscopiques qu'on 

trouve aupres des eau thermales de Carlsbad: Almanach de Carlsbad, 1835-1839. 
Crow, W. B., 1925, The reproductive differentiation of colonies in Chlamydomonadales: 

New Phytology, v. 24, p. 120-123. 
Daily, W. A., 1942, The Chroococcaceae of Ohio, Kentucky, and Indiana: American 

Midland Naturalist, v. 27, p. 636-661. 
1945, Additions to the filamentous Myxophyceae of Indiana, Kentucky, and Ohio: 

Butler University Botanical Series, v. 7, p. 132-139. 
Davis, C. C, 1955, The marine and freshwater plankton: Lansing, Mich., Michigan State 

University Press, 562 p. 
DeCandolle, A. P., 1805, Flore francaise: Paris. 

Deflandre, G., 1926, Monographic du genre Trachelomonas Ehr: Nemours, 162 p. 
Drouet, F., and Daily, W. A., 1939, The planktonic freshwater species of Microcystis: 

Field Museum Botanical Series, v. 20, p. 67-83. 
1956, Revision of the coccoid Myxophyceae: Butler University Botanical Studies, 

v. 12, p. 1-218. 
Ducellier, F.. 1915, Note sur un nouveau Coelastrum: Bull. Soc. Bot. Geneve, v. 7, p. 

73-74. 

Ehrenberg, C. G., 1832a, Beitrage zur Kenntniss der Organisation der Infusorien und 
ihre geographische Verbreitung besonders in Sibirien: Abhandlungen der konglische 
Akademie der Wissenschaften, 1830, p. 1-88. 

1832, Uber die Entwicklung and Lebensdauer der Infusionsthiere; nebst ferneren 

Beitaragen zu einer Vergleuchung ihrer organischen Systeme: Abhandlungen der 
konglische Akademie der Wiissenschaften, 1831, p. 1-154. 

1835, Dritter Beitrag zur Erkenntniss grosser Organisation in der Richtung des 

kleinsten Raumes: Abhandlungen der konglische Akademie der Wissenschaften, 
1833, p. 145-336. 

1837, Zusatze zur Erkenntniss grosser organischer Ausbildung in den klein- 
sten thierischen Organismen: Abhandlungen der konglische Akademie der 
Wissenschaften, 1835, p. 151-180 
-1838, Die Infusionsthierchen als vollkommene Organismen: Leipzig. 



Elenkin, A. A., 1924, De spec, duabus gen. Microcystis Kutz. notula: Bull. Jard. Imp. Bot. 
Pierre le Grand, v. 3, no. 1, p. 12-15. 

Ficke, J. F., and Hawkinson, R. O., 1975, The National Stream Quality Accounting Net- 
work (NASQAN)-Some question and answers: U.S. Geological Survey Circular 719, 
23 p. 

Fjerdingstad, E., 1950, The microfauna of the river Molleaa, with special reference to the 
relation of benthal algae to pollution: Folia Limnologiae Scandinavica, no. 5, 123 p. 

Forbes, S. A., 1913, Biological and chemical conditions of the upper Illinois River: Pro- 
ceedings of the Fifth Meeting, Illinois Water-Supply Association, Urbana. 

Fresenius, G., 1858, Beitrage zur Kenntniss mikroskopischer Organismen: Abhandlung 
Sench. Nat. Ges., Frankfurt, v. 2, p. 211-242. 

Fritsch, F. E., and Rich, F., 1929, Freshwater algae (exclusive of diatoms) from 
Griqualand West: Transactions of the Royal Society of South Africa, v. 18, p. 1-92. 

Geitler, L., 1927, Uber die Auxosporen von Meridion circulare und verwandten 
Diatomeen-Gattungen: Mikrokosmos, v. 21, p. 79-82. 



SELECTED REFERENCES 135 

— 1929, Uber den Bau der kerne zweier Diatomeen: Archiv Protestenk., v. 68, p. 
625-636. 
—1930, Cyanophyceae, in Rabenhorst, L., Kryptogamen-Flora von Deutschland, 



Osterreich, und der Schweiz: v. 14, p. 1-288. 
-1932, Cyanophyceae, in Rabenhorst, L., Kryptogamen-Flora von Deutschland, 



Osterreich, und der Schweiz: vol. 14, p. 673-1056. 
Gemeinhardt, K., 1926, Poren and Streifen in der Zellwand der Diatomeen: Berlin 

deutsch Botanisch Gesellschaft, v. 44, p. 517-526. 
Gerloff, J., 1940, Beitrage zur kenntnis der Variabilitat und Systematik der Gattung 

Chlamydomonas: Archiv Protistenk., v. 94, p. 311-502. 
Gomont, M., 1892a, Monographic des Oscillariees (Nostocacees homocystees), Part 1: 

Ann. Sci. Nat. Bot. VII, v. 15, p. 263-368. 
1892b, Monographie des Oscillariees. (Nostocacees homocystees), Part 2: Ann. Sci. 

Nat. Bot. VII, v. 16, p. 91-264. 
Greeson, P. E., 1970, Numerical taxonomy: The systematic categorization of the North 

American genera of freshwater algae: American Water Resources Association, Pro- 
ceedings of a Symposium on Hydrobiology, p. 150-161. 
ed., 1979, A supplement to methods for collection and analysis of aquatic biological 

and microbiological samples (U.S. Geological Survey Techniques of Water- Resources 

Investigations, book 5, chapter A4): U.S. Geological Survey Open-File Report 

79-1279, 92 p. 
Greeson, P. E., Ehlke, T. A., Irwin, G. A., Lium, B. W., and Slack, K.V., eds., 1977, 

Methods for collection and analysis of aquatic biological and microbiological samples: 

U.S. Geological Survey Techniques of Water- Resources Investigations, book 5, chap. 

A4, 332p. 
Grunow, A., 1860, Die Desmidiaceen und Pediastreen einiger Osterreichischen Moore, 

nebst einigen Bemerkungen uber beilde Familien im Allgemeinen: Ver. K. K. 

Zool.-Bot. Ges. Wein, v. 8, p. 489-502. 
Hansgrirg, A., 1892, Prodromus der Algenflora von Bohmen. Zweiter Theil welcher die 

blaugriien Algen (Myxophyceen, Cyanophyceen), nebst Nachtragen zum ersten 

Theile und einer systematischen Bearbeitung der in Bohmen verbreiteten 

saprophytischen Bacterien and Engleenen enthalt: Archiv fur Natural Landes von 

Bohm, v. 8, p. 1-268. 
Harper, R. A., 1961, On the nature of types in Pediastrum: Memoirs of the New York 

Botanical Garden, v. 6, p. 91-104 
1918, Organization, reproduction, and inheritance in Pediastrum: Proceedings of 

the American Philosophical Society, no. 57, p. 375-439. 
Hassall, A. H., 1845, A history of freshwater algae: London, 462 p. 
1850, A history of the freshwater algae, including descriptions of Desmidiaceae 

and Diatomaceae: London, 2 volumes, 462 p. 
Johnson, L. P., 1944, Euglenae of Iowa: Transactions of the American Miocroscopical 

Society, v. 63, kp. 97-135. 
Kolkwitz, R., and Marrson, M., 1908, Okologie der pflanzlichen Saprobien: Berichte der 

Deutschen Botanischen Gesellschaft, v. 262, p. 505-519. 
Kutzing, F. T., 1833, Algologische Mittheilungen. I. Uber Gloionema, Agh. II. Uber 

eine neue Gattung der Confervaceen: Flora, v. 16, p. 513-528. 
1843, Phycologia generalis, oder Anatomie, Physiologie, und Systemkunde der 

Tange: Leipzig, 458 p. 
1845, Phycologia germanica, d. i. Deutschlands Algen in biindigen Besch- 



reibungen: Nordhausen, 340 p. 
-1849, Species algarum: Leipzig, 922 p. 



Lackey, J. B., 1939, Notes on plankton flagellates from the Scioto River: Lloydia, v. 2, p. 
128-143. 



136 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Lagerheim, G., 1882, Bidrag till kannendomen om Stockholmstrakens Pediastreer, Pro- 

tococcaceer och Palmellaceer: Ofvers. Kgl. Svensk.-Ak. Forh, v. 39, no. 2, p. 47-81. 
Lefevre, M., 1932, Monographie des especes d'eau douce de genre Peridinium: Archives 

de Bot., v. 2, p. 1-210. 
Lemmermann, E., 1898, Beitrage zur Kenntnis der Planktonalgen. I. Golenkinia Chodat, 

Richteriella Lemm., Franceia nov. gen., Phythelios Frenzel. Lagerheimia Chodat, 

Chodatella nov. gen., Schroederia nov. gen.: Hedwigia, v. 37, p. 303-312. 

1899, Das Genus Ophiocytium Naegeli: Hedwigia, v. 38, p. 20-38. 

Lyngbye, H. C., 1819, Tentamen Hydrophytologiae Danicae: Kjobenhaun. 

Meister, F., 1912, Die Kieselalgen der Schweiz: Beitr. Kryptogamenfl. Schweiz., v. 4, p. 

1-254. 
Meneghini, G., 1837, Conspectus algologiae euganeae: Patavia, 37 p. 
Meyen, F. J., 1829, Beobachtungen uber einige niedere Algenformen: Nova Acta Acad. 

Caes. Leop.-Carol., v. 14, p. 768-778. 
1839, Jahresberichte uber die Resultate der Arabeiten im felde der 

physiologischen Botanik von dem Jahre 1838: Arch, fur Naturg., v. 2, p. 1-153. 
Morren, Charles, 1830, Memoire sur un vegetal microscopique d'un nouveau genre, pro- 
pose sous le nomme Microsoter, ou conservateur des petites choses: Annals of 

Science in Naturale Botonicae, v. 20, p. 404-426. 
1838, Recherches physiologiques sur les hydrophytes de la Belgique. Premier 

Memoire. Histoire d'un genre nouveau de la tribu Confervees, nomme par l'auteur, 

Aphanizomene: Memoire Akadamie Royale Belguque, v. 11, p. 5-20. 
Nageli, C. W., 1849, Gattungen einzelligen Algen, physiologische und systematische 

bearbeitet: Zurich, 137 p. 
1855, in Braun, Algarum unicellularum genera nova vel minus cognita: Leipzig, 

111 p. 
Office of Water Research and Technology, 1976, Algal abstracts- A guide to the 

literature, Volume 3: 1972-1974: New York, IFI/Plenum Data Company, 890 p. 
Office of Water Resources Research, 1973a, Algal abstracts- A guide to the literature, 

Volume 1: to 1969: New York, IFI/Plenum Data Corporation, 585 p. 
1973b, Algal abstracts-A guide to the literature, Volume 2: 1970-1972: New 

York, IFI/Plenum Data Corporation, 693 p. 
Pascher, A., 1913, Zur Gliederung der Heterokonten: Hedwigia, v. 53, p. 6-22. 
1927, Volvacales-Phytomonadinae, in Pascher, A., Die Siisswasserflora 

Deutschlands, Osterreichs, und der Schweiz, Heft 4: Jena, p. 1-506. 
1943, Zur Kenntnis verschiedener Ausbildungen der planktonischen Dinobryon: 



Inter. Rev. Gesamt. Hydrobiol. Hydrograph, v. 43, p. 110-123. 
Patrick, Ruth, 1948, Factors affecting the distribution of diatoms: Botanical Review, v. 

14, p. 473-524. 
1949, A proposed biological measure of stream conditions, based on a survey of the 

Conestoga Basin, Lancaster County, Pennsylvania: Proceedings of Academy of 

Natural Sciences of Philadelphia, v. 101, p. 277-347. 
-1973, Use of algae, especially diatoms, in the assessment of water quality: 



Philadelphia, American Society for Testing and Materials, ASTM STP 528, p. 76-95. 
Patrick, Ruth, and Reimer, C. W., 1966, The diatoms of the United States exclusive of 

Alaska and Hawaii, Volume 1: Fragilariaceae, Eunotiaceae, Achnanthaceae, 

Naviculaceae: Philadelphia, Monographs of the Academy of Natural Sciences of 

Philadelphia, number 13, 688 p. 
Prescott, G. W. 1962, Algae of the western Great Lakes area with an illustrated key to 

the genera of desmids and freshwater diatoms: Dubuque, Iowa, William C. Brown 

Co., 977 p. 
-1968, The algae: A review: Boston, Houghton Mifflin Co., 436 p. 



SELECTED REFERENCES 137 

Printz, H., 1913, Eine systematische Ubersicht der gattung Oocystis Nageli: Nyt. Mag. 

Naturvidensk, v. 51, p. 165-203. 
Purdy, W. C. 1922, A study of the pollution and natural purification of the Ohio River, I. 

The plankton and related organisms: U.S. Public Health Service Bulletin no. 131, p. 

1-78. 
Rabenhorst, L.. 1864, Florae Europaea algarum aguae delcis et submariane: Leipzig, 3 

volumes. 
Ralfs, J., 1848, The British Desmidieae: London, 226 p. 
Reinsch, P. F., 1867, Die Algenflora des mittleren Theils von Franken: Nuremberg, 238 

P- 

1888, Familiae Polyedriearum monographia: Notarisia, v. 3, p. 493-516. 

Rosenberg, M., 1944, On a blue-green cryptomonad, Chroomonas Nordstedtii Hansg.: 

Annals of Botany, v. 8, p. 315-322. 
Rosowski, J. R., and Parker, B. C, eds., 1971, Selected papers in phycology: Lincoln, 

University of Nebraska, 876 p. 
Schiller, J., 1933, Dinoflagellatae (Peridineae) und Verwandte, in Raberhorst, 

Kryptogamen-Flora Deutschlands, Osterreich, und der Schweiz: v. 10, Abt. 3, 1 Teil, 

p. 1-617. 
Schmidle, W., 1893, Beitrage zur Algenflora des Schwarzwaldes und der Rheinbene: Ber. 

d. Natur. Ges. Freiburg, v. 7, p. 1-45. 
Schmidt, P., 1923, Morphologie und Biologie der Melosira varians mit einem Beitrag zur 

Mikrosporenfrage: Internat. Rev. Gesamt. Hydrobiol. Hydrograph, v. 11, p. 114-147. 
Schiitt, F., 1896, Bacillariales. in Engler and Prantl, Die naturlichen Pfanzenfamilien: v. 

1 p. 31-150. 
Skvortzow, B. B., 1925, Die Euglenaceengattung Trachelomonas Ehrenberg. Eine 

systematische Ubersicht: Proceedings of the Sungari River Biological Station, no. 1, 

p. 1-101. 
1937, Diatoms from Lake Michigan. I: American Midland Naturalist, v. 18, p. 

652-658. 
Smith, G. M., 1916, A monograph of the algal genus Scenedesmus based upon pure 

culture studies: Transactions of the Wisconsin Academy, v. 18, p. 422-530. 
1920, Phytoplankton of the inland lakes of Wisconsin: Bulletin of the Wisconsin 

Geological and Natural History Survey, v. 57, p. 1-243. 
1926, The plankton algae of the Okoboji region: Transactions of the American 

Microscopical Society, v. 45, p. 156-233. 
1931, Pandorina Charkowiensis Korshikov: Bulletin of the Torrey Botanical Club, 

v. 57, p. 365-366. 

— 1950, The freshwater algae of the United States: New York, McGraw-Hill, 719 p. 
-ed., 1951, Manual of phycology-An introduction to the algae and their biology: 



New York, Ronald Press Co., 373 p. 
Stein, F. R. von, 1883, Der Organismus der Infusionsthiere nach eigenen Forschungen in 

systematischer Reinenfolge bearbetiet. III. Abteilung. II Halfe. Die Naturgeschichte 

der Arthrodelen Flagellaten: Leipzig, 30 p. 
Teiling, E., 1946, Zur Phytoplanktonflora Schwedens: Bot. Notiser, 1946, p. 61-88. 
Thienemann, August, 1939, Grundziige einer allgemeinen Okologie: Archives 

Hydrobiologica, v. 35, p. 267-285. 
Thompson, R. H., 1938, A preliminary survey of the freshwater algae of eastern Kansas: 

University of Kansas Science Bulletin no. 25, p. 5-83. 
Tiffany, L. H., 1934, The plankton algae of the west end of Lake Erie: Ohio State Univer- 
sity, Contributions of the Franz Theodore Stone Laboratory, no. 6, p. 1-112. 
Turpin, P. J., 1828, Apercu organographique sur le nombre deux: Memoir Museum 

d'Hist. Nat. par les Prof, de cet establissement, v. 16, p. 296-344. 



138 ALGAE IN PHYTOPLANKTON OF THE UNITED STATES 

Vaucher, J. P., 1803, Histoire des conferves d'eau douce: Geneva. 

Weber, C. I. 1966, A guide to the common diatoms of water pollution surveillance system 

stations: Cincinnati, Ohio, Federal Water Pollution Control Administration, 101 p. 
West, G. S., 1908, Some critical green algae: Journal of the Linnean Botanical Society of 

London, v. 38, p. 279-389. 
West, W., and West, G. S., 1905, A further contribution to the freshwater plankton of the 

Scottish lochs: Transactions of Royal Society of Edinburgh, v. 41, p. 477-518. 
1908, A monograph of the British Desmidiaceae, Volume 2: London, Ray Society, 

204 p. 
-1912, On the periodicity of the phytoplankton of some British lakes: Journal of Lin- 



nean Society of Botany, London, v. 40, p. 395-432. 

Whipple, G. C, Fair, G. M., and Whipple, M. C, 1948, The microscopy of drinking 
water, 4th ed.: New York, John Wiley and Sons, 586 p. 

Williams, L. G., 1962, Planktonic population dynamics: U.S. Public Health Service 
Publication no. 663, supp. 2, 93 p. 

1964, Possible relationships between plankton-diatom species numbers and water- 
quality estimates: Ecology, v. 45, p. 809-823. 

1966, Dominant planktonic rotifers of major waterways of the United States: Lim- 



nology and Oceanography, v. 11, p. 83-91. 



irU.S. GOVERNMENT PRINTING OFFICE: 1982-36 1 -6 1 4/3 1 I 



1, %$&•