A FLORISTIC STUDY OF THE ATTACHED ALGAE OF LAKE MIZE, FLORIDA By HELEN DAVIS BROWN A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 1972 Copyright by Helen Davis Brown 1972 ACKNOWLEDGEMENTS For his continued encouragement and guidance, the author wishes to thank Dr. Dana G. Griffin, III, Chairman of the Supervisory Committee. The writer would also like to extend her sincere thanks to Dr. Richard Smith and Dr. Frank Nordlie for generously providing both advice and special equipment for certain portions of the study. Thanks are also due Dr. Leland Shanor , Dr. Henry Aldrich, Dr. James Kimbrough, and Dr. Frank Nordlie for critically studying this manuscript and for providing valuable suggestions for its improvement. The author would also like to express gratitude to Dr. Clark Cross for his help in various ways during the study and to A. Baker, Dr. Alan Brook, and Marilyn Lash for their assistance in devising some of the equip- ment and procedures used in this investigation. Acknowledgements and thanks are also accorded the following authorities, each of whom provided identifications of certain species critical to the study: Dr. William Daily, Dr. L. A. Whitford, Dr. Robert Bland, Dr. Hannah Croasdale, Dr. Alan Brook, and Dr. James Lackey. The use of Lake Mize, Florida, as a study area was graciously provided by Dr. John Gray, Chairman, Department 111 of Forestry, and by Mr. Don Post, Director, Austin Gary Memorial Forest. The facilities at Elk Lake, Minnesota, were made available by the Itasca Biology Station, Univer- sity of Minnesota (Dr. William Marshall, Director). Financial assistance for various portions of this study was provided by an assistantship from the Botany Department, University of Florida; by a Graduate School Fellowship from the University of Florida; and by NSF grant GB 3390 (Itasca Biology Station) . Finally, the writer would like to thank her parents, family, and friends for their encouragement and support during the course of this study. XV TABLE OF CONTENTS Page ACKNOWLEDGEMENTS iii LIST OF TABLES ix LIST OF FIGURES XV ABSTRACT xviii I . INTRODUCTION 1 II . LITERATURE REVIEW 3 Terminology 3 Growth Forms of Attached Algae 5 Substrates Used in Studying Attached Algae 5 Vertical Zones of Periphyton Distribution 9 Suocessional Tendencies in the Periphyton 10 III . DESCRIPTION OF THE STUDY AREAS 14 Lake Mize 14 Location 14 Morphometry 15 Chemistry and Physios 15 Recent History of Lake Mize 23 Aquatic Macrophytes of Lake Mize 24 Surrounding Vegetation of Lake Mize 25 Elk Lake 27 IV. MATERIALS AND METHODS 30 General Sampling 30 Use of Sub strates 30 Littoral Area Methods 31 Limnetic Area Methods 34 Collecting Procedures 36 Species Composition Method 36 Physical Measurements 39 V TABLE OF CONTENTS — Continued Page V. OBSERVATIONS AND RESULTS 4 0 Limitations of the Study 40 Lake Mize Studies 42 Colonization of Substrates by Algae 42 Spatial Variation in the Periphyton in Lake Mize 46 Seasonal Variation in the Periphyton in Lake Mize 49 Attached Algae Present in the Limnetic Area of Lake Mize, Winter^ 1968-1969 50 Vertical Distribution of Attached Algae on Glass Slides, December , 1968, to February, 1969 51 Variation in Algal Flora on Glass Slides with Time, Winter, 1968-1969 59 Attached Algae Present in the Limnetic Area of Lake Mize, August to September, 1969 63 Vertical Distribution of Attached Algae and Other Periphyton on Glass Slides, August to September, 1969 64 Changes in the Algal Flora on Glass Slides with Time, August to September, 1969 80 Adaptive Algal Forms Present , August to September, 1969 84 Attached Algae of the Littoral Area, August, 1969 85 Planktonic Algae, August to September, 1969 88 Attached Algae Present in the Limnetic Area of Lake Mize, August, 1970 88 Vertical Distribution of Attached Algae and Other Periphyton on Glass Slides, August, 1970 89 Variations with Time in the Algal Flora Present on Limnetic Area Slides, August, 1970 99 Vi TABLE OF CONTENTS — Continued Page Vertical Distribution Patterns of Attached Algae and Other Periphyton on Websteria submersa^ August^ 1970 100 Variations with Time in the Algal Flora Present on Websteria submersa, August, 1970 116 Comparison: Algal Flora of Glass Slides and of Websteria submersa, August, 1970 117 Planktonic Algae, August 13, 1970 123 Attached Algae of the Littoral Area, August, 1970 124 Attached Algae on Glass and Plastic Slides, Littoral Area, August, 1970 127 Other Littoral Studies, May, 1969; July, 1969; April, 1971; July, 1971; and September, 1971 138 Planktonic Algae, September , 1971 149 Elk Lake Studies 150 Vertical Patterns of Attached Algae and Other Periphyton on Glass Slides in Elk Lake, July to August, 1967 151 Variation with Time in the Algal Flora Present on Glass Slides, Elk Lake Limnetic Area, August, 1967 158 Attached Algae of the Littoral Zone, Elk Lake, Agusut , 1967 160 Comparison: Attached Algae of Lake Mize, Florida, and Elk Lake, Minnesota 161 VI. DISCUSSION 164 Losses Due to Peeling 164 Changes with Time: Colonization and Succession 165 Influence of the Sub strate 167 Vll TABLE OF CONTENTS — Continued Page Influence of Physical Factors — Current 172 Influence of Physical Factors — Light 173 Influence of Physical Factors — Temperature 174 Seasonal Influences 175 VII. SUMMARY 178 APPENDIX 181 LITERATURE CITED 199 BIOGRAPHICAL SKETCH 2 04 Vlll LIST OF TABLES Table Page 1. Secchi Disc Measurements in Lake Mize, October 2, 1968, to August 13, 1970 20 2. Temperature Measurements from the Surface Waters of the Littoral Zone of Lake Mize, August, 1968, to August, 1970 22 3. Representative Sampling Errors as Experienced in the Proportions and Frequencies of Mougeotia sp. , Diatoms, and Algae on Replicate Glass Slides Exposed at a Depth of 6 Inches for 4 Weeks During the 1968-1969 Winter Study 43 4. Dominant Algal Species Found on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 1 Week, December 7 to December 17, 1968 53 5. Proportions of Algal Divisions and Attached Protozoa Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 1 Week, December 9 to December 17, 1968 54 6. Dominant Algal Species Found on Glass Slides Suspended in the Limnetic Area of Lake Mize for 4 Weeks, December 17, 1968, to January 9, 1969 55 7. Proportions of Algal Divisions and Attached Protozoa Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, December 17, 1968, to January 9, 1969 56 a.x LIST OF TABLES — Continued Table Page 8. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Lake Mize for 1 Week, December 9 to December 17, 1968 60 9. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Lake Mize for 4 Weeks, December 17, 1968, to January 9, 1969 61 10. Dominant Algal Species Found on Glass Slides Suspended in the Limnetic Area of Lake Mize, for 1 Week, August 7 to August 14, 1969 65 11. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Lake Mize for 1 Week, August 7 to August 14, 1969 69 12. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, August 7 to August 28, 1969 70 13. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 6 Weeks, August 7 to September 11, 1969 71 14. Dominant Algal Species Found on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, August 7 to August 28, 1969 74 LIST OF TABLES — Continued Table ^^9^ 15. Dominant Algal Species Found on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 6 Weeks, August 7 to September 11, 1969 77 16. Proportions of Algal Divisions and Other Groups of Organisms Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 6 Weeks, August 7 to September 11, 1969 79 17. Proportions of Algal Divisions and Attached Protozoa Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, August 7 to August 28, 1969 82 18. Proportions of Algal Divisions and Attached Protozoans Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 1 Week, August 7 to August 14, 19 69 83 19. Dominant Algal Species Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 90 20. Dominant Algal Species Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 94 21. Proportions of Algal Divisions and Other Groups of Organisms Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 97 XI LIST OF TABLES — Continued Table Page 22. Proportions of Algal Divisions and Other Groups of Organisms Present on Glass Slides Suspended for 4 Weeks in the Limnetic Zone of Lake Mize, July 23 to August 20, 1970 98 23. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 101 24. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Lake Mize for 4 Weeks, July 23 to August 20, 1970 102 25. Number of Algal Species Present at Various Depths on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 103 26. Number of Algal Species Present at Various Depths on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 104 27. Proportions of Algal Divisions Present on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 108 28. Proportions of Algal Divisions and Attached Protozoa Present on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 109 Xll LIST OF TABLES — Continued Table Page 29. Dominant Algal Species Found on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 HO 30. Dominant Algal Species Found on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 HI 31. Comparison of Algal Flora Present on Vertically Positioned Glass Slides and on the Aquatic Plant, Websteria submersa, on August 13, 1970, after 3 Weeks' Suspension in the Limnetic Zone of Lake Mize, Florida (VA = Very Abundant, A = Abundant, C = Common, I = Infrequent, and R = Rare) .... 118 32. Number of Algal Species Present on Glass and Plastic Slides Exposed in the Littoral Area of Lake Mize at a Depth of 18 Inches, Collected August 15 and 20, 1970 128 33. Frequencies of Dominant Algal Species Present on Glass and Plastic Slides Exposed in the Littoral Area of Lake Mize at a Depth of 18 Inches, Collected August 15 and 20, 1970 129 34. Attached Algae Found on Glass Slides, Websteria submersa , and Sphagnum maarophyllum Placed in the Littoral Area of Lake Mize (Station 1) , 18 Inches Below the Surface for 4 Weeks, July 21, August 15, 1970 132 35. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 1 Week, July 21 to July 28, 1967 154 Xlll LIST OF TABLES — Continued Table Page 36. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 2 Weeks, July 21 to July 28, 1967 155 37. Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 3-1/2 Weeks, July 21 to August 14, 1967 156 38. Master List of the Attached Algae of Lake Mize, Florida, and Planktonic Species Associated with Communities of Attached Algae, December, 1968, to September, 1971 182 39. Master List of the Attached Algae and Planktonic Species Associated with Attached Algae in Elk Lake, Minnesota, August, 1967 192 40. The Algal Flora Present on Vertically Positioned Glass Slides Suspended in the Limnetic Zone of Lake Mize during January, 1969; August, 1969; and August, 1970 (VA = Very abundant , A = Abundant , C = Common , I = Infrequent, R = Rare) 194 xiv LIST OF FIGURES Figure Page 1. Bathymetric map of Lake Mize, showing sampling stations 1, 2, 3, and 4. (Courtesy of Dr. Frank Nordlie) 16 2. North-South view of Lake Mize, Florida 17 3. Light penetration in Lake Mize, Florida (Winter) 19 4. Light penetration in Elk Lake on August 14, 1967 28 5. Glass slide showing periphyton present after 3 weeks' exposure in Lake Mize (xl) 33 6. Plastic enclosure used in Lake Mize littoral studies (xl/lO) 33 7. Areas counted, indicated by lines, on glass slides in Lake Mize studies 37 8. Frequencies of 3 algal divisions present on glass slides suspended in the limnetic area of Lake Mize for 1 week, December 9 to December 17, 1968, and for 4 weeks, December 17, 1968, to January 9, 1969 52 9. Frequencies of 3 algal division and of the dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 1 Week, August 7 to August 14, 1969 67 10. Frequencies of the dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 3 weeks , August 7 to August 28, 1969 68 XV LIST OF FIGURES — Continued Figure Page 11. Frequencies of dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 6 weeks, August 7 to September 11, 1969 73 12. Frequencies of 3 algal divisions on glass slides suspended in the limnetic area of Lake Mize for 3 weeks, August 7 to August 28, 1969, and for 6 weeks, Agusut 7 to September 11, 1969 81 13. Frequencies of dominant algal species and the major groups of attached organisms present on glass slides suspended in the limentic area of Lake Mize for 3 weeks, July 23 to August 13, 1970 92 14. Frequencies of dominant algal species and the various groups of attached organisms present on glass slides suspended in the limnetic area of Lake Mize for 4 weeks, July 23 to August 20, 1970 93 15. Frequencies of dominant algal species present on Websteria submersa suspended in the limnetic area of Lake Mize for 3 weeks, July 23 to August 13, 1970 106 16. Frequencies of dominant algal species present on Websteria submersa suspended in the limnetic area of Lake Mize for 4 weeks, July 23 to August 20, 1970 107 17. Germlings of Bulhoohaete sp. on Websteria submersa (x400), Lake Mize 187 XV 1 LIST OF FIGURES — Continued Figure ^^9^ 18. Colony of Protoderma viride , a prostrate Chlorophyte , with diatoms, Nitschia palea and Frustulia rhomboides (xl,400), Lake Mize 187 19. Osaillatoria tenuis filaments (xl,300). Lake Mize 187 20. Anabaena osoillavioides (xl,000), Lake Mize 187 21. Closterium setaaeum (x320), Lake Mize 189 22. Closterium navicula (x600), Lake Mize 189 23. Oedogonium sp., showing holdfast (x400), Lake Mize 189 24. Branched filaments of Hapalosiphon fontinalis (x500), Lake Mize 189 25. Portion of the attached community of a glass slide, showing Cosmarium regnellii Eunotia sp. , and a filamentous Oomycete (x600) , Lake Mize 191 26. Frustulia rhomboides var. saxoniaa (x750) , Lake Mize 191 27. Rhipidodendron splendidum , a heterotrophic Chrysophyte (X300), Lake Mize 191 28. Epithemia zebra (x400), Elk Lake 191 XVI 1 Abstract of Dissertation Presented to the Graduate Council of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy A FLORISTIC STUDY OF THE ATTACHED ALGAE OF LAKE MIZE, FLORIDA By Helen Davis Brown August, 1972 Chairman: Dr. Dana G. Griffin, III Major Department: Botany A floristic survey from December, 1968, to September, 1971, provided a record of the communities of attached algae in Lake Mize, Florida. Counts and estimates of organism densities were used to determine the relative abundance of species. In all, 89 species were identified and monitored during the study period. Both quantitatively and qualitatively, desmids and filamentous Chlorophytes were usually an important part of the periphyton in Lake Mize. Several acidiophilic diatoms were abundant at certain times, while Cyanophytes generally reached high frequencies only during the July to September period. In the course of the investigation, it was determined that algal species employing particular modes of attachment were more abundant under some conditions than others. XVlll Generally, tightly adhering, resupinate forms attained higher densities on glass slides than filamentous and loosely associated metaplanktonic species. Conversely, the epiphytic flora of the filamentous sedge, Websteria suhmersa, contained a large number of both strong and weak attachers. Other broad-leafed macrophytes in the lake normally had an epi- phytic flora composed mainly of filamentous and/or resupinate species with somewhat fewer metaplanktonic algae than the flora of W. submersa. However, no absolute substrate speci- ficity could be shown for any one species or by any attaching form. A major observation to come from this investigation was that the attached flora varied not only with substrate type, but that different areas of the lake supported some- what different periphyton communities. In calmer areas of the lake or in protected enclosures, metaplanktonic and filamentous species were more abundant on all substrates than in areas subjected to currents and turbulence. When clean substrates (slides or plants) were submerged, the pioneering attachers were usually the most abundant resupinate and/or filamentous forms in the lake at that time. Debris became associated with the attached algae community for a period up to 5 weeks. The number of meta- planktonic species increased as well as total algal frequen- cies. In excess of 3 to 5 weeks, peeling ensued with a subsequent loss of debris and algae, especially debris- associated metaplanktonic forms. XIX Whereas the type of substrate and the amount of current appeared to be critical in determining whether weak attachers would be present in a given periphyton community, light was also important in governing the floristic compo- sition of the community in Lake Mize. Chlorophytes were generally abundant only in the upper 6 to 18 inches of the lake. Chrysophy tes , on the other hand, had a broader vertical range, frequently remaining common to a depth of 30 inches on glass and 42 inches on W. submersa. In the case of Cyanophytes, light requirements were variable. Some species were restricted to the upper 6 to 18 inches of the lake and others were common to a depth of 42 inches. A comparison of the attached flora in Lake Mize, Florida, a dystrophic lake, with that of the mesotrophic Elk Lake, Minnesota, revealed a number of differences. Taxonomically , the attached floras of the two lakes were almost completely different with only three species common to both lakes. Diatoms formed the major part of the attached flora in Elk Lake, while Chlorophytes were generally the dominant algal division in Lake Mize. In Lake Mize, light was a severely limiting factor with attached algae usually restricted to the upper 30 to 42 inches of the lake and with maximum algal frequencies occurring in the upper 6 to 18 inches. In Elk Lake, attached algae were common to a depth of 4 meters. Maximum frequencies usually occurred at a depth of 3 meters. XX I. INTRODUCTION The objectives of this investigation were: (1) to analyze the composition of the attached algae communities which appeared in Lake Mize, Florida, December, 1968, to September, 1971; (2) to observe the successional tendencies among the communities of attached algae in Lake Mize; (3) to compare the attached algae communities on glass slides with those on several aquatic macrophytes; and (4) to compare the attached algae of Elk Lake, Minnesota, with those of Lake Mize. Attached algae, which are part of the periphyton, have an important role in a lake's food web. However, studies of the periphyton in fresh-water lakes have not been as numerous as planktonic studies. To the author's knowledge, no study has been made of periphyton in a northern Florida lake. Thus, while the limno logical features and the plankton of Lake Mize have been studied (Harkness and Pierce, 1941; Nordlie, 1967), no prior study has been made of its nonplanktonic algae. As a monomictic, brown-water lake. Lake Mize holds considerable interest. This investigation, together with those already made, will add to our understanding of the lake as a functioning ecosystem. - 1 - 2 - A pilot study of attached algae was first carried out at Elk Lake, Minnesota, during the summer of 1967. Elk Lake is a dimictic, raesotrophic lake. The results of this investigation provide an interesting contrast with those obtained from the summer studies in Lake Mize. II. LITERATURE REVIEW Termino logy The term periphyton has been given several meanings in the literature (Cooke, 1956). In this study, periphyton is used to designate "that assemblage of organisms growing upon free surfaces of submerged objects in water," as defined by Young (1945). Aufwuchs , a German term, carries much the same meaning (Sladeckova, 1962). Algal members of the periphyton are termed phyao-periphyton (Foerster, 1963) or, attached algae (Brook, 1955; Castenholz, 1960). Phyco-periphyton may be classified according to the nature of the substrate upon which they occur; i.e., epiphytic algae, those found attached to plants and epilithic algae, those attached to rocks and stones. Epipelic algae are those algae associated with lake bottom sediments (Round, 1964). The members of the metaplankton were first considered to be the algae lying between aquatic plants (Behre, 1956). The meaning of this term has been broadened so that the metaplankton are considered to be those algae loosely associated with a substrate, but not sessile upon it (Round, 1964). In this study the metaplankton are considered to be part of the attached - 3 - - 4 - algal flora when found adhering to a substrate. It is recognized that these forms are also part of the "plankton" of the lake's littoral zone. A community is considered by Odum (1959) to be "any assemblage of populations living in a prescribed area or physical habitat." The term oommunity is often used to refer to various assemblages of attached algae. With reference to the attached algae, the term denotes a group of species found together on a certain type of substrate (Castenholz, 1957). Within a community distinct groupings of species called associations occur (Margalef, 1953). Succession is the orderly process of community change (Odum, 1959). With reference to the attached algae, a pioneer community occurs first on a given substrate. This pioneer community is replaced by a series of more mature communities. In most situations, whether the community of attached algae ever reaches what may be properly tearmed a otimax is debatable (Blum, 1956b) . In this study, when the terms succession or successional tendencies are used, reference is being made simply to the series of communities which follow each other in occupying a given substrate in the lake. - 5 - Growth Forms of Attached Algae While the raembers of the plankton are adapted to flotation, those of the periphyton are adapted to attach- ment on a substrate. Generally, organisms in a given community tend to have certain growth forms. Both Round (1964) and Fritsch (1929) report 2 main growth forms among the attached algae: (1) species appressed to the substrate, broad surface down; and (2) species which produce a small attachment disc from which either a single cell or a filament projects. Examples of the first form include numerous diatoms and some members of the Chaetophorales. Examples of the second form include green filamentous algae, as Oedogonium, and diatoms attached by a mucilaginous pedicel, as Synedra. A third growth form is sometimes considered to occur, that of filaments within a thick mucilage, as Nostoc (Round, 1964). A holdfast cell or mucilage is the mode of attachment for all forms. Substrates Used in Studying Attached Algae In the investigation of attached algae on natural substrates, certain difficulties are encountered. Epilithic algae must be removed from their rocky substrate in order to be studied microscopically. Removal of closely adhering forms is difficult so that an extremely - 6 - accurate assessment of the epilithic community is usually not possible. A method proposed by Margalef (1949a) holds promise of partially overcoming this difficulty. His method consists of applying a film of collodion to the rock or stone and then peeling the film off when it dries. To some degree, the difficulty imposed by the closely adhering forms is also met when the attached algal flora of aquatic macrophytes is studied. Sometimes, however, the epidermis of the plant may be peeled, or Margalef 's method may be used (Margalef, 1949b) . An additional problem in studying algal succession upon aquatic macrophytes is the problem of obtaining clean plants with- out epiphytes. To overcome this difficulty, Prowse (1959) grew plants in water containing silver ions. This solution acted as an algicide and a fungicide to suppress the growth of algal and fungal epiphytes on the plants. Whitford (1956) studied the succession of algal epiphytes by comparing growth on younger parts of an aquatic raacrophyte with that on older parts. Most investigations of attached algae have featured the use of artificial barren surfaces. Many different artificial barren substrates have been used: polyethylene tape (Neal , Patten, and DePoe, 1967), plastic, wood, slate, sheet metals, asbestos, and glass (Sladeckova, 1962) . The use of glass slides is especially widespread. - 7 - Sladeckova (1962) reports Kny (1884) as the first to use this method for the study of zoospore attachment in the laboratory. Hentschel (1916) was the first to use the glass slide method in the qualitative and quantitative determination of periphyton. The method has been modified many times since Hentschel ' s work. Both smooth and scratched glass slides have been used (Castenholz , 1957) . The glass slide method provides the advantage of making possible the direct microscopical observation of attached organisms. Several investigators have attempted to compare the attached algal community found on glass slides with that found on natural substrates. The species present on glass slides appear to be almost the same as those found on aquatic macrophytes and stones (Castenholz, 1957; Dor, 1970). Blue-greens, however, do not colonize glass slides as readily as natural substrates, according to several workers (Castenholz, 1957; Sladeckova, 1962). Numerical analyses of the species present frequently yield different results with slides as compared to natural substrates (Blum, 1956a; Dor, 1970). While differences exist between the attached algal flora of glass slides and of natural substrates, differ- ences also exist among various forms of natural substrates. - 8 - Among aquatic macrophytes , Carex and Chara have few attached epiphytes while Fontinalis and Myriophyllum are densely populated by algal epiphytes, according to Round (1966) . Some species of attached algae also grow much more readily on some plants than on others (Tiffany, 1951; Young, 1945; Prowse, 1959). Varying parts of a plant may have different attached communities (Tiffany, 1951). Also, while the epiphytic and epilithic communities share many species, stones tend to have more encrusting forms than do plants (Ruttner, 1963). Light and ease of attachment have been theorized to be the most important factors in the distribution of algal epiphytes (Tiffany, 1951). Other factors also may account for differences in the attached algal flora of various substrates. Substrates which contain irregu- larities seem to make attachment easier (Blum, 1956a). Current is probably very important (Ruttner, 19 63; Whitford, and Schumacher, 1963) . Castenholz (1957) theorized that 1 species of CZadophora did not appear on glass slides due to the timing of its dispersal mechanism (zoospore production) . He also found that when slides were exposed 6 weeks or longer, they developed encrusting blue-green forms not usually found on slides. A time differential may also explain some of the differences between the species composition of plants and of stones. - 9 - Many aquatic plants are short-lived and are probably populated mainly by quickly developing attached forms. Rocks allow the colonization by forms which develop slowly (Ruttner, 1963). Vertioal Zones of Periphyton Distribution Several workers have studied the vertical distribution of periphyton in lakes or reservoirs, using artificial substrates (Maciolek and Kennedy, 1964; Neal , Patten, and Depoe, 1967; Sladeckova, 1966). Maciolek and Kennedy (1964) report that in Laurel Lake, California, attachment on glass slides was greatest at the 5-meter level. Diatoms were the chief attaching forms. Neal, Patten, and DePoe (1967) used polyethylene tape as the substrate for attachment in a polluted lake near Oak Ridge, Tennessee. Maximum biomass development was found to take about 2 weeks in the euphotic zone (upper 50.8 centimeters) and longer below the euphotic zone. Biomass accumulation was greatest in the upper 38.1 to 54.7 centimeters. Species succession continued after maximum development of biomass occurred. Succession began with blue-greens and diatoms. These pioneers were succeeded by filamentous and adhering greens. In Polish reservoirs, Sladeckova (1966) considers periphyton distribution to be divided into 5 zones within the water column: - 10 - 1. A surface zone without periphyton • 2. Zone of producers (euphotic zone) , algae predominate ; 3. Transition zone (compensation layer) , mixture of producers and consumers present • 4. Zone of consumers, rotifers, sessile protozoans, etc. , predominate ; 5. Bottom zone, influenced by decomposition process in the sediments, bacteria and large benthic organisms present . The above vertical periphyton distribution probably holds true for most water bodies with sufficient depth. At any depth, growth of periphyton is a balance between income and loss processes. Gains occur through colonization and primary productivity. Losses occur through respiration, secretion, excretion, sloughing off of the periphyton film, and grazing by consumers (Neal, Patten, and DePoe, 1967). SuGcessi-onal Tendencies in the Periphy ton Ecological succession in general is characterized by a number of important features. By definition, it is an orderly process of community development that is reasonably predictable. Succession results from a modification of the habitat by the organisms present in the habitat. It is culminated by a climax community in equilibrium with the physical environment. The physical - 11 - environment determines the pattern of succession, the rate of change, and how far succession may proceed (Od\am, 1969) . Early stages of succession have been compared to later stages in a number of ways. Species with high rates of reproduction and growth are more likely to survive in early successional stages, while those species with capabilities for competitive survival are more likely to be present during later successional stages (Odum, 1969) . Pioneer species are also better adjusted to indiscriminate dispersal. During succession, there are increases in the proportion of inert or dead matter, in biomass , in the number of niches present, and in stratification. There is frequently an increase in species diversity. Or, diversity may increase and then decrease (Margalef , 1968) . Succession is a frequent occurrence. However, orderly unidirectional succession does not always occur in nature. When the physical environment is extreme or subject to large-scale fluctuations, succession either does not continue or is pushed backward (Odum, 1969; Margalef, 1968) . Several studies have been made that deal with successional tendencies in the periphyton community (Whitford, 1956; Yount , 1956; Brook, 1954; Whitford and Schumacher, 1963). The use of glass slides is common. - 12 - Colonization of bare substrates placed in a lake proceeds rapidly. Within a few hours to a few days, bacteria attach (Sladeckova, 1962). According to Brook (1967) the first algal colonizers on slides in the ponds of filter plants are generally small blue-green filaments and diatom members of the Monoraphidae. Both of these groups usually appear within a week. Later, large prostrate greens, especially members of the Chaetophoraceae , appear. Competition between closely adhering diatoms and the prostrate greens may be severe with the outcome sometimes influenced by grazing. In North Carolina Piedmont streams during early spring, Whitford and Schumacher (1963) found diatoms to form the first 2 successional stages on bare substrates. The third stage was a gelatinous mat of the blue-green, Phormidium subfuscum , with 2 associated diatoms. This was followed by filamentous greens, such as Miarospora and Stigeoolonium . As has been pointed out previously, the actual achievement of climax by the periphyton is questioned by some investigators for many situations. Blum (1956b) doubted that the climax concept should be applied to the ephemeral algal communities of streams. However, he also reasoned that the equivalent of a "permanent" climax may be reached by algae in a single season. In North Carolina streams, Whitford and Schumacher (1963) found no - 13 - perennial community of attached algae and questioned the use of such terms as climax, dominant, and succession for communities of attached algae. Within some Florida springs, a climax community of attached algae has been reported (Whitford, 1956; Yount , 1956). However, streams are recognized as being stable ecosystems with physical and chemical conditions rather uniform throughout the year except for light (Whitford, 1956). III. DESCRIPTION OF THE STUDY AREAS Lake Mize The major part of this study was carried out at Lake Mize, Florida. Several workers have conducted extensive investigations at Lake Mize (Harkness and Pierce, 1941; Nordlie, 1967; Brezonik and Harper, 1969; Brezonik, 1970). Some aspects of their studies will be utilized in this description of Lake Mize, as well as the observations of the writer. Lake Mize may be characterized as a limestone solution lake (Nordlie, 1967) . The sedimentary rock underlying much of Florida is composed chiefly of limestone. In a limestone area, depressions or "sinks" sometimes develop due to the dissolving of carbonate deposits along fault lines. These sinks may then fill with water during subsequent Florida wet seasons and a lake is produced (Nordlie, 1967) . Location Lake Mize is located in the Austin Gary Memorial Forest, 10 miles northeast of Gainesville, Florida, latitude 29° 44' north, longitude 82° 13' west (Harkness and Pierce, 1941) . - 14 - - 15 - Morphometry Lake Mize has a surface area of 0.86 hectare and a maximum depth of 25.3 meters (Nordlie, 1967). It is generally circular in outline except for a shallow bay on the north side of the lake (Figures 1 and 2) . Except for the bay area, the depth of the lake increases rapidly from the shoreline. The littoral zone is represented by a narrow band outlining most of the lake. When the water level is high, a temporary stream carries the overflow into Hatchett Creek , The water level of Lake Mize varies considerably during any one year as the rainfall fluctuates. Chemistry and Physios Lakes are generally classified as to nutrient level, i.e., eutrophic, mestrophic, oligotrophic, or dystrophic. Lake Mize is a dystrophic lake. Its brown water is so colored by the leachate from the surrounding pine forest (Brezonik, 1970) . According to Brezonik (1970), color values as high as 700 mg/ii , platinum scale, are common in the lake. The dissolved and suspended organic materials in the lake help to produce a distinctly acid pH . Nordlie (1967) found the median pH of Lake Mize to be 4.2 for 1965. Brezonik (1970) found the median pH to be 5.2 - 16 - LAKE MIZE JUNE 24,1954 (CONTOURS IN METERS) Figure 1. Bathymetric map of Lake Mize, showing sampling stations 1, 2, 3, and 4. (Courtesy of Dr. Frank Nordlie) - 17 - Figure 2. North-South view of Lake Mize, Florida. - 18 - for the period June, 1969 to June, 1970. Total acidity, as measured by Nordlie for the 1965 period, ranged from a low of 10.5 to a high of 30.0 ppm for the surface waters. Lowest values were obtained during the summer and highest values during the winter. This range in values shows that the waters of Lake Mize have a poor buffering capacity (Nordlie, 1967). Algae and other aquatic organisms in the lake are consequently exposed to fluctuations in pH and water chemistry. The dissolved and suspended organic matter also affects the penetration of light in Lake Mize. Secchi disc readings during the period October 2, 1968, to August 13, 1970, ranged from 1 foot to 4 feet (Table 1). According to Ruttner (1953) , secchi disc readings in lowland lakes generally range from a few decimeters to 10 meters. It can be seen that the secchi disc readings for Lake Mize fall in the lower part of this range. A secchi disc reading is considered to be a measure of the depth of visibility in a lake and to give some measure of the transparency of the water. Measurements made with a light meter showed light penetrating to around 3 feet December 9, 1968; to 6 feet on February 9, 1969; and to the 1 foot level on February 15, 1970 (Figure 3). - 19 - -p -p a 32 48 64 82 98 Percent of surface illumination Figure 3. Light penetration in Lake Mize, Florida (Winter) . - 20 - TABLE 1 Secchi Disc Measurements in Lake Mize, October 2, 1968 to August 13, 1970 Secchi Reading Date Hour in feet October 2, 1968 10:30 a.m. 2-1/4 October 13, 1968 1:00 p.m. 4 December 9, 1968 11:30 a.m. 2-1/4 December 17, 1968 11:30 a.m. 3-1/2 January 9, 1969 4:00 p.m. 2-3/4 February 20, 1969 4:00 p.m. 2-1/2 April 17, 1969 3:00 p.m. 1-3/4 April 23, 1969 3:00 p.m. 1-3/4 November 29, 1969 10:00 a.m. 1 February 15, 1970 3:00 p.m. 1 July 16, 1970 7:00 p.m. 1-1/2 August 13, 1970 5:00 p.m. 1-1/2 Phosphate measurements from the epilimnion of Lake Mize ranged from nondetectable to 0.1 mg i PO4 for 1965, according to Nordlie (1967) . And, for the time period of August 1, 1968, to June 12, 1970, Brezonik (1970) reported an upward trend in phosphate values with a range from 0.027 mg P/Z to 0.225 P/£. - 21 - Nitrate-nitrogen measurements in surface samples from Lake Mize ranged from a value not detectable to 0.40 mg N/£ during 1965 (Nordlie, 1967). In the deep water, values occurred up to 0.83 mg N/£ (Nordlie, 1967). Recently, Brezonik and Harper (1969) have shown that nitrogen fixation by bacteria occurs in Lake Mize. Brezonik (1970) reported organic nitrogen values ranging from 0.55 mg N/ii on August 1, 1968, to 125 mg U/l on June 12, 1970. Several studies (Harkness and Pierce, 1941; Nordlie, 19 67) have shown Lake Mize to be a monomictic lake, i.e., a lake having one period of circulation during the year. In Lake Mize constant circulation occurs during the winter season, generally from November through February (Brezonik, 1970). Temperature measurements by the author on December 9, 1968, showed the surface waters to be 15°C. At a depth of 1 foot, the water measured 14-1/2°C. From the 1-foot level to the bottom, the water temperature dropped only 1/4°, from 14-1/2° to 14-1/4 °C. Measurements taken on February 20, 19 69, indicated a slight stratification. The surface temperature was 17°C with a drop to 11.2°C at the bottom. (Surface tempera- tures generally ranged from 16° to 35°C throughout the year as indicated by Table 2.) 22 - TABLE 2 Temperature Measurements from the Surface Waters of the Littoral Zone of Lake Mize, August, 1968, to August, 1970 Date Hour Temperature, °C. August 16, 1968 4:00 p.m. 33 August 27, 1968 10:00 a.m. 31 September 3, 1968 1:00 p.m. 26 October 2, 1968 10:30 a.m. 24 November 8, 1968 10:00 a.m. 21 November 15, 1968 2:30 p.m. 20 December 2, 1968 2:00 p.m. 22 January 17, 1969 2:00 p.m. 16 February 20, 1969 3:30 p.m. 18 April 10, 1969 2:00 p.m. 23 May 9, 1969 2:00 p.m. 33 August 8, 1969 2:00 p.m. 35 November 29, 1969 10:00 a.m. 18 February 15, 1970 11:00 a.m. 16 February 15, 1970 3:00 p.m. 18 July 16, 1970 7:00 p.m. 35 July 21, 1970 10:00 a.m. 30 August 13, 1970 2:00 p.m. 29 - 23 - Without circulation of the lake's waters, a stable thermal stratification develops. In Lake Mize, thermal stratification persists from late February or early March to late October or early November, depending upon weather conditions (Brezonik, 1970) . During this period of stratification, anaerobic conditions occur below a depth of 3 to 5 meters from April or May until the end of stratification (Brezonik, 1970; Nordlie, 1967). During the period of circulation and homiothermy , oxygen is introduced into the deeper waters of the lake (Nordlie, 1967) , although oxygen depletion may still exist in the deepest waters of the hypolimnion (Brezonik, 1970) . Nordlie (1967) found the oxygen concentration at a depth of 70 feet to be 0.5 ppm on December 18, 1964. Recent History of Lake Mize The recent history of Lake Mize has included the introduction of a flock of mallard ducks for scientific study. During most of the period from August, 1968, until the present, the ducks have been confined to an enclosure on the north side of the lake in the bay area. During the spring and summer of 1970, a portion of the flock was free to roam on the lake. In a study to determine the influence of the ducks on Lake Mize, as well as to evaluate any possible potential - 24 - disruptive effects on the lake's ecosystem, Brezonik (1970) found a trend of gradually increasing phosphate and nitrate values during the period of August 1, 196 8, to June 12, 1970 (cf. p. 20). He also found chlorophyll a values during 1969 to be almost twice as high as the values Nordlie found for 19 65. Primary productivity values also increased (Brezonik, 1970; Nordlie, 1967). Brezonik theorized that from 50 to 90% of the duck food being added to Lake Mize was not utilized by the ducks. This unused duck food represents a significant portion of the nitrogen and phosphorus entering Lake Mize at present, according to his calculations and those of Shannon (1970). Aquatic Macrophytes of Lake Mize Some changes in the populations of aquatic macrophytes also occurred in the 1968-1970 period. During April, 1968, the following species of floating, submerged, and emergent aquatic plants were common in Lake Mize: Paniaum hemitomon , Leersia oryzoides , Websteria submersa , Utrioutaria olivacea , Sphagnum maarophyllum , and Mayaca aubletii. Potamogeton floridanus also occurred in the bay area of the lake, but was not common or widespread. Several of the common species gradually decreased over the 2-year period. A survey taken during April, 1970, showed the following to be absent: S. maarophyllum , L. oryzoides , and M. aubletii. The population of P. hemitomon had - 25 - increased greatly and surrounded the lake, growing both in shallow water and on shore. W. submersa was present in reduced amounts, as compared to the 19 68 survey. Some of the aquatic macrophytic species of Lake Mize occasionally grow both submerged and as shore plants. During periods of low water, submerged aquatic macrophytes are left stranded on the sloping shore. Such conditions usually bring desiccation to the aquatic plants. However, S. macrophyllum , W. submersa, and M. aubletii grow both as submerged plants in Lake Mize and as terrestrial plants on shore during low water. This is also a common occurrence at other soft-water lakes of northern Florida and Georgia. Sculthorpe (1967) comments that while it is common for floating aquatic plants to have land forms, few land forms of submerged plants have been described. Floating plants also occur to a limited degree in Lake Mize. Masses of W. submersa, usually mixed with U. olivaoea, are sometimes present on the surface of the lake. The floating plant Lemna minor is sporadically present in Lake Mize. Surrounding Vegetation of Lake Mize Besides the land forms of some of the submerged plants of Lake Mize, there are a number of herbaceous and shrubby plants around the lake. The herbaceous species include: Polygonum hirsutum , Hyperiaium myrtifolium , - 26 - Paniaum hemitomon, Fuirena scirpoidea, Rynahospora sp. , Cyperus sp. , Eriaaulon deaangulare , Xyris amhigua, Ludwigia atataj Rhexia mariana , Diodia hirsuta, Pluohea rosea, Potypremum prooumhens , Elephant opus tomentosus , Eupatorium oapilli folium, E. aomposiii folium , Osmunda cinnamonea, Pteridium aquilinum , Hydroootyle umhellata , Sagittavia graminea, Diodia virginiana, D. teres, Andropogon' sp. , Conyza canadensis , and Lyonia lucido. A number of woody plants, trees, shrubs, and vines border the lake on the south and west sides. These include: Diospyros virginiana , Magnolia virginiana , Myrica oerifera , Ilex glabra, Serenoa repens , Vaccinium stamineum , Cephalanthus oaoidentalis , Quercus hemisphaerioa , Q. geminata, Q. laevis , Q. inaana, Callioarpa amerioana, Smilax glauoa, S. laurifolia, and S. bona-nox . Lake Mize is situated within the body of a pine forest which surrounds the lake. Important tree species in the forest include: Pinus palustris , P. taeda, P. elliotii y Quercus nigra, and Q. laurifolia. The understory consists largely of Serenoa repens. Ilex glabra and Vaccinium spp. The forest, in addition to its influence on the lake's chemistry and coloring, also provides some measure of protection from wind. - 27 - Elk Lake In order to compare the perphyton of Lake Mize with a different kind of lake, a portion of this study was carried out at Elk Lake, Minnesota. Elk Lake is located at Itasca Biology Station, Minnesota. It has a single outflow stream, Chambers Creek, by which it is also connected to Lake Itasca. Several springs and streams run into Elk Lake. Elk Lake has a surface area of 102 hectares, a maximum depth of 29 meters, a volume of 1.13 x 107 cubic meters, and a shoreline length of 4.78 x 103 meters (Baker and Davison, 1966) . Elk Lake may be characterized as a mesotrophic lake. It is dimictic, having overturn periods in the spring and fall. During the winter season it is generally covered by ice. The water of Elk Lake is green in color. During the summer of 1967 light penetrated generally to a depth of around 10 meters (Figure 4). During the study period, tem- perature was fairly uniform for the top meters, 24 °C on July 24, 1967. Below the 4- meter level, there was a rapid decline in the thermocline to 8°C at the 10-meter level. At the 29- meter level, temperature registered around 6°C. - 28 - 16 32 48 64 82 98 Percent of surface illumination Figure 4. Light penetration in Elk Lake on August 14, 1967. - 29 - The littoral area of Elk Lake is populated by a number of aquatic plants, including several species of Soirpus . Except for the southwest corner, it is surrounded by deciduous forest, which provides some protection from winds . IV. MATERIALS AND METHODS General Sampling The attached algae of Lake Mize, Florida, were first studied during December, 1968. The study was concluded in September, 1971. During this study period, collections were made of the attached algae present in the littoral area during May, 1969; July, 1969; August, 1969; August, 1970; April, 1971; July, 1971; and September, 1971. Studies of the attached algal species present in the limnetic area were made during December, 1968; January, 1969; February, 1969; August, 1969; September, 1969; and August, 1970. Three stations were maintained in the littoral area and 1 in the limnetic area (Figure 1, p. 16). At Elk Lake, Minnesota, glass slides were used to study attached algal forms present in both the littoral and limnetic areas during August, 1967. This timing permitted comparison with the August studies in Lake Mize. At Elk Lake, 1 station was maintained in the limnetic area and 1 in the littoral area. Use of Substrates A number of substrates were used in studying the attached algal flora of Lake Mize. Among inert substances, - 30 - - 31 - glass slides were the most commonly used (Figure 5) . Pieces of plastic were also submerged in the lake tor attachment by the phyco-periphyton. The aquatic macrophytes which were sampled for epiphytic growth during the study included: Sphagnu„ macrophyllu^ , Webst.r-ia submersa, Famous h.„itomon, Leersia ory.oidee . Mayaoa auilM, Folyeonu. Ursutu.. and Vt.icula.ia oHva.ea. As previously mentioned, some of these aquatic macrophytes found at Lake Mize are amphibious , "i .e . , found growing at time of low water on the shore as well as submerged in the lake. The shore forms of these plants were gathered and grown in closed glass containers in the laboratory. These plants, assumed to be without epiphytes, were submerged in the lake in order to study the progressive growth of epiphytic communities. Because of its frequent occurrence and physiological hardiness, *'. subn,.vsa was the plant most commonly used in this way. Other amphibious plants so used were M. aubleti , S. .acvophyllu. , F. sclvpoidea . and Baoo^a aaroliniana . Littoral Area Methods in the littoral area of Lake Mize, slides and plants were submerged in rectangular plastic baskets at a depth of 18 inches (Figure 6). The baskets had a loosely woven framework. A few were lined with plastic screening Figure 5. Glass slide showing periphyton present after 3 weeks' exposure in Lake Mize (x 1). Figure 6. Plastic enclosure used in Lake Mize littoral studies (x 1/10) . - 33 - - 34 - to provide protected enclosures. Aquatic macrophytes were planted in sand at the bottom of the baskets. Vertically positioned glass slides were also placed in the baskets. The slides were placed in wooden slide boxes which had the bottoms removed and the boxes were then attached to the sides of the baskets. The basket enclosures with plants and slides were generally left in place for varying periods up to 6 weeks. Occasionally large glass jars were also used as enclosures for macrophytes. Outside the enclosures slides in boxes were sometimes attached to upright poles or to ropes secured by an anchor and buoy. Plants occurring naturally in the littoral area were also sampled. Specific methods, collection dates, and exposure periods differed in the various littoral studies. Details concerning aspects of each separate study are included in Chapter V. Limnetic Area Methods Comparative studies were made at Lake Mize, Florida, and Elk Lake, Minnesota, of the attached algae present in the limnetic areas. In August, 1967, the attached algal flora on vertical glass slides placed in the limnetic area of Elk Lake, Minnesota, was studied. Slides were attached to wooden blocks in which slits had been cut. The blocks were attached to a rope. The rope - 35 - was then attached to a buoy at the surface of the lake and to an anchor at the lake's bottom. Slides were suspended at the surface, at l-meter intervals to the 5- meter level, and at 2-meter intervals from the 7-meter level to the 15-meter level. In Lake Mize, 3 similar studies were conducted during the following time periods: December, 1968, to February, 1969; July to August, 1969; and July to August, 1970. Slides were placed in wooden slide boxes with the bottom sections removed. In an arrangement similar to that carried out at Elk Lake, the boxes were attached to a rope. The rope was then attached to a buoy and an anchor and suspended in the middle of the limnetic area of the lake near the deepest. Since Lake Mize is a brown-water lake with limited light penetration, slides were placed nearer the surface than at Elk Lake, Slide racks were generally attached to the rope at levels of 6, 18, 30, and 42 inches. In the 1968-1969 winter study and the August to September, 1969, study, slide racks were also placed at deeper depths (see p. 50 and p. 63) . In August, 1970, the sedge, Websteria suhmersa , was also suspended on a rope-buoy system during the same time as the suspension of glass slides. As indicated earlier, this macrophyte occurred naturally from time to time in the lake as floating mats, so that its retention - 36 - on an artificial rope-buoy approximated the floating state. Suspensions were made at levels of 6, 18, 30, and 42 inches with groups of the plants tied to the rope at these levels. The suspended plants remained alive throughout the study period. Considerable plant growth occurred at the first 2 levels. Various exposure periods were used for slides and plants during the study, ranging from 6 hours to 6 weeks. Exposure periods and collection dates are enumerated for each part of the study in Chapter V. Collecting Procedures After collecting, plants and slides (Figure 5) were placed in liquid preservative prepared according to the following formula.* Dioxan 50 cc Formalin 6 cc Acetic Acid 5 cc Water 40 cc This solution preserved most algae so that plastid color was retained. Algae which were alive at the time of collection could be distinguished from dead forms. Species Composition Method In the Lake Mize limnetic studies and in the August, 1970, littoral study, proportions and frequency of *McWhorter and Weier, 1936. - 37 - the various species present on glass slides and on some plants were calculated. With the glass slides, after 1 side of the slide was wiped clean, algae on the unwiped side were examined directly. Species were usually identi- fied before any cell counts were made. Counts were made in 2 prescribed areas of the slide, since observation indicated that algal populations were not evenly distributed on the slides. On most slides, heavier concentrations of algae were generally present near the edges of the slides. Counts were therefore made in 2 areas extending as lines, as indicated by Figure 7. Along these 2 lines, counts were made of the algae present in randomly selected fields, using a 43x objective and a lOx ocular. Figure 7. Areas counted, indicated by lines, on glass slides in Lake Mize studies. In his study of attached algae, Castenholz (1957) found that counting 300 individuals in randomly selected microscopic fields gave reasonable statistical accuracy. - 38 - In the writer's Lake Mize study, Castenholz ' s counting procedure was generally followed with the first 300 individuals recorded. Sometimes on sparsely populated slides, it was necessary to count only 100 individuals. And, on heavily populated slides, 500 to 1000 individuals were counted. Frequencies per square centimeter for individual species and for the total algae present were calculated. Relative abundance as presented in Table 42 of the Appendix was based on these calculations. Proportions of the various species among the 300 attached forms counted were also calculated. Among the aquatic macrophytes, it was possible to examine directly the attached flora of S. maorophyllum. However, the attached algae of most aquatic plants were observed by scraping off the epidermis with its attached organisms from a prescribed portion of the plant. Scrapings were placed on a slide, a drop of water added, and the mixture stirred. Counts were then made with the first 300 individuals recorded. Proportions of the various species among the 300 recorded were calculated. In the case of the linear plant, W. submersa , plant area was measured before the epidermis was scraped so that frequency could be calculated for comparison with glass slides. With the Elk Lake study and with some of the collections made from the Lake Mize littoral areas, species - 39 - proportions and frequency were not calculated. Identification was made of the species present and dominants were noted. Based on frequency calculations or estimates, several terms are used throughout this study in order to describe relative abundance of an algal taxon. These terms and the meaning ascribed to them by the writer are listed as follows: 1. VeTy Abundant: Over 5000 cells, filaments, or colonies per square centimeter 2. Abundant: 2000 to 5000 cells, filaments, or colonies per square centimeter 3. Common: 500 to 2000 cells, filaments, or colonies per square centimeter 4. Infrequent: 100 to 500 cells, filaments, or colonies per square centimeter 5. Rave: 10 to 100 cells, filaments, or colonies per square centimeter 6. Dominant : Algal species present in largest numbers (numerical dominance) Physical Measurements A Whitney light meter was used to measure light penetrance in Lake Mize. For temperature measurements, a precision oxygen analyzer was used in the limnetic area and a pocket thermometer in the littoral area. V. OBSERVATIONS Al^D RESULTS The results of the Lake Mize and Elk Lake studies are organized chiefly according to: (1) the period of the observation (month and year) and (2) the site of the observations in the lake, i.e., whether in the littoral or limnetic area of the lake. Data relating to the statistical reliability of the observations of this study are also presented. A master list of the species found in Lake Mize, Florida, is included in the Appendix (Table 38) as well as photographs of selected species identified during the study. A list of species identified from Elk Lake, Minnesota, is also included in the Appendix (Table 39) In addition, a third table (Table 40) is included which presents comparative frequencies of a number of algae identified during the limnetic studies. Limitations of the Study In determining the relative abundance of species of attached algae under various conditions in Lake Mize, 2 sources of error deserve consideration. One source of error in making comparisons is derived from the unavoidable loss of attached material from the substrate while collecting. This loss of material could be observed both - 40 - - 41 in the lake during collection and at the bottom of the collecting jar after preservation. In making this study, it was assumed that the amount of material lost from various substrates while collecting was the same. Precau- tions were taken while collecting so that the loss of material was minimal. The material at the bottom of the collecting jars was also periodically examined for species which might not appear in the material still attached to the substrate. Proportions of species in the material at the bottom of collecting jars were also checked. These proportions were similar to those proportions of species remaining attached to the substrate except for slightly higher losses of metaplanktonic species. The factors contributing to these losses are discussed in Chapter VI. Another source of error is the statistical error found in the counts which provide the basis for some of the comparisons in this study. Brook (1953) in a study of bottom-living algae of sand filter beds in waterworks, found that sampling error for 1 filter bed was around 23% when 10 collections were made. However, because changes in time were so marked, he still found it possible to make valid comparisons in his successional study. The sampling errors in the present study were also high. For a given algal species, counts made from replicate substrates frequently showed a variation as high as that of Brook's study. Occasionally the variation was - 42 - even higher (Table 3) . However, significant differences in frequencies and in proportions among species did commonly occur under different environmental conditions. Differ- ences with time were also sometimes marked. The variation present among counts from replicate substrates was due to a complex interaction of factors and will be elaborated upon in Chapter VI. Lake Mize Studies Eighty-nine species of algae were identified as part of the periphyton in Lake Mize or as planktonic forms associated with the periphyton. Thirteen other species were present but could not be identified to species, chiefly due to the lack of reproductive structures in the Zygnematales and Oedogoniales collected. Of the 102 species present, 63 were Chlorophytes , 2 were Euglenophytes , 22 were Chrysophytes, 2 were Pyrrophytes, 1 was a Xanthophyte, and 1 was a Chloromonadophyte. Colonization of Substrates by Algae Glass slides placed in the lake and removed after 6 hours were populated by a variety of forms. Many bac- teria were attached to these slides. Planktonic algae were common on those slides exposed for a short period of time. Epiphytic algae common natural substrates in the lake at the time were also present. - 43 - T! w C w (0 (0 r-1 tn o 0) C -G 0 OJ -P •iH 4-1 4-) 05 (T" M O C o •H •H iiiH 5-1 o CU 3 u (U a C^ « en 0) c ,^ ^ o (U +J a) 0) S C to •rH tn^ iH • T3 < v< >1 Q) 0 T3 U T3 M-l 13 C C -P (U to en cn •H (D M ^ j=: u m 0) en o QJ a. e c 4-1 W X 0 H G ^^ W -P •H m to »J3 S <: en •H EH fO Q 14-1 CTl O <-0 w ^ cn M • ^ nH 0 &.-P 1 u en DjCO u 0) U3 M C Q CT> •t^ -H iji 4^ to C O -H ca -P nH fa5 to Oj s g O TS (0 :§: Q) Ol en iW 0 Q) o 04 > X ■H en w ■P (U (C ■<-{ en -P o 0) c G 13 (U 0) •H en 3 rH (U tj-t/) i-i (U O^ H (1) Cn (^ 0) Id o\o U Q e/5 M tu N 0. ^ 1 0 >|4J 1 U (U c e 0) -H 3 4J tr C g; Q) >H U Cp en to oV> u Q i -G c &, lO -H •H J4 T3 (U QJ Ch S 14-1 0 44 en 0 0) 4-J * to 0 rH 1 2 (X, c 0 X to Eh (3^ r- O • • • cn (N in H •^ >X) a\ iH o LO in IT) >>D v£) ■=3' lO in "^ ■^ U3 in in iH r^ •r4 rH iH (j\ eviation t of variat 'd* •^ ■<* ndard d ff icien • to P -H O (U — ' a (M (U ^ (d m x: iJ e u w c ^ M-l •H •H 4J -- 0 c 1 aio\p (C -P V£> •H V£) < J a> rH HH Si QJ 0 U X^ nc; - C -P -^ +j ^ M •rH DjO\0 rH (D 1 (U ^ c X! "sT ^O •H (0 ^ in 13 Id 2 Q) tJI x: ^ :3 rH u x: C <; fl3 C -P -- O Q) 4-) •H OioXO <-t Qj 0 0 1 0) — W -p EH oj t3 M 13 ^ iJ CO Q) CQ r^ Xi < t/3 4J x; E-i (D +J U X! 13 w UH C 4J ^ ■H 0 o -H OjcfO iH ty 1 0) --- to 3 4J o 13 < c n W Q) tn w O fO ^ !h Xi iH 0) 0) u x: o 0) P^ C -P ^ IS •H Ojo\o c 1 OJ -- o rH CXD Xi T3 Sh G o Id m x: 0 u x: fa (0 1 0) — • 0) VD t3 •H o 0) cu w H (d 01 iH < ■p c rt c • •H g o Q 00 LO n VD in 00 in n (N en ro in 00 CN OM CN (N m a a 03 •ri w o Ss s m •^ !i Si-ri 4J t-^ s •^ 3 r^ O to >. --^ s e K a, o <» x: •r^ Q) s^ Q> o <» s cu O 401 o 4-i u f^ 0 OJ rs; 0 <^ c O fl4 <-\ rC x: >i u u 66 - slides exposed for 1 week (see Figures 9 and 10) . On slides exposed for 3 weeks highest frequencies occurred at a depth of 6 inches. G. vesiculosa was abundant at this depth and then common to rare at all other depths. Other Chlorophytes present included several species of Oedogonium, Ankistrodesmus falcatus , Cosmarium sp., Protoderma viride , Soenedesmus dimorphus , Closterium intermedium , and the planktonic Helicodictyon planatonicum . All were rare to infrequent. Most of these Chlorophytes were restricted to slides suspended at 30 inches or above (Tables 11, 12, 13). However, the desmid,. Cosmarium sp. , occurred rarely on slides to a depth of 20 feet, and germ- lings of Oedogonium sometimes occurred infrequently on slides to a depth of 10-1/2 feet. The planktonic alga, H. planatonicum , was also recorded, though rarely, to a depth of 20 feet. Among the three dominant Cyanophytes present were two shade-tolerant species, Phormidium tenue and Oscillatoria tenuis, which occurred to a depth of 5-1/2 feet. Both species displayed a broad limnological toler- ance, occurring on slides near the surface as well as at much greater depths. The highest recorded frequency for any alga on glass slides during the entire study period occurred in P. tenue. These exceptionally high counts were taken from slides submerged to a depth of 6 inches - 67 - Q) Xi o c •H c •H -a •J-l Q 18- 30 42 - 54 _ 66 o o H u n 0) -p o >1 u ^ — I— I — H- J — I — I — h -t- Frequency; 1 unit = 3,000 cells, filaments, or colonies per square centimeter CO 0) xi o a •H G •H J3 +) Oi 0) Q 18 30 42 54 66 s s ?^ o CO •^^ 3 a O « to o Frequency: 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 9. Frequencies of 3 algal division and of the dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 1 week, August 7 to August 14, 19 69. -68- Frequency ; 1 unit = 3,000 cells, filaments, or colonies per square centimeter Frequency: 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 10. Frequencies of the dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 3 weeks, August 7 to August 28, 19 69. -69 0) Xi 4J C -H 13 «^ (U VD T^ cr> C .H QJ &. - Ul ■^ 3 -H C/3 4J m tn Q) d Ti Cr> •H 13 .H < CO 0 cn +J en td rH r^ O A-> C w O 3 d^ tn ;3 ^ < 4J Cu - r-l Q) M rH Q QJ 0) M w ;s J 3 CQ 0 rH -i (fl O > iw -P Q) fO N •H ■P S C 0) 0) W X 0) rd Sh 1^ a, ^-^ in O Q) •H (0 U 0) (U u cu< Ui o rH -H (C 4J Cr« Q) rH C < e •H iw i-q O M (1) X! 0) ■H u U2 o u QJ X! 3 o c -H I O x: u -H I X! x; +j a, 0) oa T3 u x; c: 4J •H a, I 0) VD t3 x: u x; G -P •H Oj I QJ ^ Ti in x: o x: d -p •iH a. I 0) x; u x: c -p ■H Cl. 1 (U o tS n x: O X! c -p -H a. 1 (1) 00 ^ rH x; o x; c -p •H CL. 1 Q) UD ^d n VO CTN CTi 00 VO LO XI (d UJ XI (d in U UJ Q) Q) -p c QJ tn X! (d tn tn QJ w X! -H II (U (U U) 4J 0 e U 4-> +J QJ >i -P 3 0) • >i >i ■P x; >i 2 0. X) x: x: >i Oi X W (d 04 O4 x: 0 O4 rH 0 0 04 c 0 (d <4H u w 0 QJ x; ■P 0 •• o >1 c rH +j 0 QJ •-i 5h (d tP c E-" -P x; x: >i 3 (d 0 o u u w X a 7 0 0) xi +> c •H cr\ T( vo QJ cr> -a nH c a) ^ DjOO en CN :3 w 4-1 W m 3 (U Cn 'O 3 •H < .H CO O -P W W (C r^ rH O 4-> CO C Hi o en 3 m < Xi ■p «k Ol, m fN Q) X rH Q Q) m +J 0) m N ■H +J S c (U 0) to Ai Q) (13 5-1 i-q CM m W o 0 rH a < e ■H U-l v^ o M 0) ^ cn 0) •H U (U CO O u Q) Xi B x: u c x: •M -P 1 CI. o (U '^r TJ (N r" <— 1 O c ,c; •H -p 1 Q. KO dj (N t3 o -G c -P •H Ou 1 m UD T! >^ ^ u ^ c -P -rH Oj 1 i -p :3 0) • >1 >1 •P x; >. 2: Ol X! Xi x; >^ Q4 x^ CO (C3 i G rH +j 0 1 3 (0 0 u U CJ w X 2 -71- 0) x^ +J c •H o^ ^ >x) 0) Td iH a QJ •» a^H w rH 3 CO U OJ U5 X! QJ e n3 a) ■rH -p rH a. CO 0) CO w t/1 0 rO -p iH O r- C 0 +J w en d ^ en -P 3 Qjrt: n tu rH Q «• w w m ^ ^q d (D PQ 0 0) < -H & EH U (0 M +) 0 (d U-) •P (U C N (U •H Ul S QJ Sh JD VD 43 (d CN +J C (U to 43 s^ to (d w Q) Q) tn to CD to 43 -H II 0) Q) to -P (U g u -p +J 0) >i 4J 13 (U • >i >i -P 45 >1 2 ft 43 45 45 >. ft 45 CO (d ft ft 45 0 ft r-i 0 0 ft £5 0 (d 14H u m 0 0) 45 •P 0 • • 0 >i C nH -p 0 tu rH u m Cr> C Eh +J 45 45 >i d (d 0 0 U u w X 2 - 72 - and exposed for 3 weeks. (Higher frequencies for other algae were recorded on plants.) Frequencies of P. tenue were also comparatively high at other depths after the same 3-week exposure period. It was very abundant on slides exposed at a depth of 18 inches, although a decrease in numbers from the upper level did occur (see Figure 10). A gradual decrease of the frequency of this alga then occurred at lower depths. It was common on slides suspended at 30 inches, infrequent at 42 inches, and rare at 54 inches. On slides exposed for 3 weeks at a depth of 54 inches, P. tenue made up a large proportion of the periphyton (Table 14) . Although it was rare at this depth, the numbers of other organisms were compara- tively lower. The frequencies of this alga were not as high on slides exposed for either 1 week or 6 weeks as on slides exposed for 3 weeks. Slides exposed for 1 week on which colonization had recently begun had frequencies for P. tenue which ranged from common (6-inch depth) to rare (54-inch depth) . Losses of Phormidium filaments from slides exposed for periods in excess of 3 weeks accounted for its decreased frequency (see Figures 10 and 11) . 0. tenuis did not occur as frequently on slides during the 1969 summer study as P. tenue. In the case of slides exposed for 3 weeks, maximum frequency occurred - 73 - m QJ o c •H ■H cu 0) Q Frequency 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 11. Frequencies of dominant algal species present on glass slides suspended in the limnetic area of Lake Mize for 6 weeks, August 7 to September 11, 1969. - 74 - w pq EH 0) (d ^q o Q) fl O o ■H +J (U e •rJ 0) cr\ C 00 -rH (N T3 4-1 0) en C tr> Q) 0 tn :3 O w •H CO W 13 U5 -( O ^ 0) o +J +J <: o u 0) e 2 -P O 0) o -p c o 0) j:: u c ^ -H +J '-- 1 a,o\o o 0) — ^ Ti (N xi u c ^ •H 4J ^ 1 !:i4 0\o U3 0) — fN ^3 U -P '-- (D ^ MD T3 o x; c -p — •H CtjoVO in Si V -p ^ (D CM '^ x: o c •H I o n -P — Q) — u x: I (U ^ 00 n3 0 ^ C -P -- •H QjCP 1 OJ ^ VD T3 ^ X! in JQ ja in (U (0 'T Id Id in OJ CM in a\ OJ vo (0 XI (d X! X! (d in o CM «d Xi (d Id rr CN CM CN in Xi Id in CN 00 o CM OJ vo o CN CN s « • CO « CO (h « to •fi CO 0 a CO -^ !^ E U) •fi T~-i E tn U) ex. 4^ 0 3 Q) ■+-i 3 s <» 0) tn « « +i CO M +J CO 0 M E -p 0 0) 0 0 « •r^ "XS ca >i S^'r^ fn <» >1 •<^ X> 0 *^ t-~i 3 •<^ 3 4:; ID CO 0 S^H X. 4i >i S ^-^ »-i S E e a, 0 Q) E --^^ CU Ci X « Q> •v^ tfl !i< <» 0 CO » CO rQ 0 c a. t^S'tj 0 -w 0 +i u t-i 0 w 3 0 EX, to .« 0 Ci 1 fel c ■=1: 0 fX, ^ u (d x: Xi >i u u u - 75 - x: V c 4:; ■H +J ^ 1 Oj*o 0 0) -^ '^ tS OJ x: w 0 g C Xi U3 ■H -P ^ •H 1 QjoXO c VD Q) ^- (ti (N ^ Cr« rH M O ^ T3 U X 0) C -P — ^ •H OioXO U 1 0) ^ fO >X) T) -p VD 4J <: X M-l U X. 0 c: +J -- •H Dj o\o ^1 1 0) — 0) ^ Ti XJ in s X 0 X iH a -P ^ fO •H QjdC -P 1 0) ^ o CN T3 Eh '^r Q) s: X -P u ^ C +J -- IH •-H QjoNO o 1 dJ — 0 t3 +J n c (U u ^ M 0 4:^ Q) C -P -- Pn -H OioXO 1 (U ^ CO 'd iH x: U X C -P ^ ■H Qjoxo 1 Q) — v£> 13 in n in CN O (0 XI m 03 03 a X! i^ CO (tJ 0 -v^ U) Eu ?^ II 0) 0 0 +J S r^ • >1 a s X! ^ rs; cjj (13 Oi fX, Q) 0 Q) ^ x; +i • a +j CO QJ c -P m 0 X 2 - 76 - at the 6-inch depth, although this alga remained common at successively deeper levels (18, 30, and 42 inches). With slides exposed for 7 days 0. tenuis attained maximum frequencies at the 42-inch depth. When slides were left submerged for periods of 5 to 6 weeks, sloughing of the periphyton layer reduced the counts for most species. 0. tenuis, for example, was recorded only rarely from slides exposed for 6 weeks regardless of depth. Unlike P. tenue and 0. tenuis, Aphanoaapse delicatissima occurred only on slides suspended in the upper 18 inches of the lake with most of its growth on 6-inch slides. It was very abundant at 6 inches and rare at 18 inches on 3-week slides (Figure 10) . Maximum fre- quencies also occurred at 6 inches on 6-week slides (Figure 11) . Other Cyanophytes found on slides during August and September, 1969, included Calothrix epiphytioa and Anabaena oscillarioides . Both of these species occurred only on slides suspended at the depth of 6 inches. C. epiphytioa was common at this depth and A. oscillarioides was infrequent at the end of the 3-week exposure period. A number of Chrysophytes appeared on slides during the August to September, 1969, study. While not abundant on slides exposed for only 1 week, Eunotia peatinalis was a dominant species on slides exposed for both 3 weeks and 6 weeks (Tables 14 and 15). After both exposure periods. -11- in w pq < Eh 0 •H +) C e -H Q) * ■P -H c u ■r^ (1) 0) (D C CU Q) Q) en d o en +J CO in Hi Cn CO C) CO O 0) :s d o M h o (0 (U 0) •H N U -H CO QJ iH (C3 (C5 iJ Cn 1-1 4-1 S-l O Ti 0) u tT3 +J <: 14-1 o u Q) +J o 0) -p m o -p c; -- (D — n3 x; QJ U C -H I o U c •H I x: -p — 0) — n3 x: -p --- Q) — 00 Ti x: u c ■H 1 X5 -p -- OnoV VO Ti CO VO (C3 XX (C3 (N CN (0 (0 CN in ro in X! (C3 r-~ in CM X) ^ n (y» fN 00 00 (N sx in (N VD (N O (N 00 CM ca -p 3 c « s 0) E <» CO tj • CO +:» « XI CO Oa « CO •t^ (0 03 O 04 to ■*; CO'ri E ?H CO •fi v1 Sl'ri >i M E '^ -p o-^ •<^ (<> 3 >1 X! Si, 10 W ^ +:> Ci S >1 S^o s t-i S si. tc3 Vu O Q) Qj o Ki y x; a <» Sh •^i CB On 0 Q> P> 0 s r^ O Q^ rS^'TS o O +^ o ).l r~i Ul 3 (3 o EX. rs; CO si •• 0 x: u Ci U fel 5: (C3 u "^ ft. o ■p Q) -P 0 2 - 78 - frequencies of this diatom were highest on slides suspended 18 inches from the surface, although it was abundant on slides suspended near the surface at a depth of 6 inches. A dramatic drop in the numbers of E. peotinalis occurred between 18 and 3 0 inches. Very abundant frequencies were recorded on slides suspended at 18 inches while only rare occurrences were noted at a depth of 30 inches (see Figures 10 and 11) . While E. peotinalis was the Chrysophyte present in largest numbers, several other Chrysophytes were rare to abundant. These included Mallomonas caudata, Frustulia rhomboides , Navicula minima^ Gomphonema lanoeolatum, and Nitsahia palea. This period marked the only recorded occurrence of G. lanoeolatum on slides in Lake Mize. Except for M. aaudata, the vertical distribution of Chrysophytes was mainly limited to the upper 18 inches of the lake as was the case with E. peotinalis . A coccoid Xanthophyte, Stephanoporos regularis , was also present on the August to September slides. The vertical distribution of this alga was unusual in that it occurred chiefly on deeper slides. Attached protozoans made up a high proportion of the periphyton on slides exposed for 6 weeks during the 1969 summer study (see Table 16) . Maximum abundance occurred at the 6-inch level with a gradual decline in frequency occurring at greater depths. A maximum frequency - 79 - Vi) EH Q) T) •H H CO CO (0 (C O o o 4-) 4J m 0) en (^ " CO g 0) W 0) •H S C tn U U O O O w o u o 0) x: 4-) o c w o •H tn -H > N 0) M (U ^ X! O 6 (1) (D 4J c a O Q) ts] en u •H -P 0) e Q (D 4:: .H 4-> (0 en C U-l (U O T3 C CO Q) G 04 -P ro O Q« O P4 e V) -rH o 0) X^ O n3 4-> -P i -p >i >i -P >i x: 0 II x: X! >i x; a, !-l tn 0) O4 a, x; CL. 0 a, d H-l • 0 0 04 0 c 0 QJ X! u en 0 x: 0) 13 •P u (tJ 0 >i c 4-) iH i .H U nJ c en x; 0) e 0) x: Xi >i (0 :3 u e 0 • • ro u u u x; w m (0 0 (U rH •rH -p 0 2 - 80 - of attached algae for the 1969 summer study occurred on slides exposed for 3 weeks which were collected August 28. Vorticelloids occurred infrequently on these slides at most depths, although they were abundant on slides sus- pended at the depths of 42 inches (Table 17). Changes in the Algal Flora on Glass Slides with Time^ August to September , 1969 Glass slides collected on each of three dates during August to September, 1969, were populated by several Cyanophyte species. Slides collected on August 14 after 1 week's exposure were dominated by the green alga, Gleocystis vesiculosa (Tables 10 and 18). After 3 weeks' exposure the populations of G. vesiculosa showed a marked decrease. Instead, three Cyanophytes were dominant: Osaillatoria tenuis, Phormidium tenue , and Aphanoaapsa delicatissima (Table 14) . Debris covered parts of the slides, giving them a brown appearance. A significant increase in algal frequency occurred. Slides collected on September 11, 1969, after 6 weeks' exposure had lost most of the debris observed on August 21. Dominance also had shifted somewhat, so that Cyanophytes and Chrysophytes were present at upper levels in almost equal proportions (Tables 16 and 17 and Figure 12). In addition, a decrease in algal frequency since August 28 had occurred. - 81 - Sl8- xi o ^ 30- o ■p ^-42- Q 54-- ■ \ ■ /. (U tn 4J M >i 0) 41^ Q) CU^ 0 C n IT5 >1 U \ 1 I 1 I I I I I I I I I I I I I 1 I 1-1 I \ 1 I I Frequency : 1 unit = 3,000 cells, filaments, or colonies per square centimeter _ 1 6- 18- — V ' "1 - \ / p 1 . m 30- \ / 0) u U) tn c (U 0) m -^ 42- m ^ Q) x: a; a Q) 0 ^ >i 0) 1 o Qa Q) ^ QJ O ^ a. ^ x; ^ to o ■^,54- O VD >lU) (0 - 0) x; ^ >( Q u U u 66- - - 78- ■ J - 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 r 1 I 1 1 iL 1 1 1 1 1 1 r 1 — ' ' ' ' ' '. J 1 ' — r- 1 1 1 1' Frequency: 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 12. Frequencies of 3 algal divisions on glass slides suspended in the limnetic area of Lake Mize for 3 weeks, August 7 to August 28, 1969, and for 6 weeks, August 7 to September 11, 1969. -82- r-~ < Eh o ■H ISl Q u iH -H fO 4-> Cn Q) rH C < g -H o 0) to ^ C -P o •H G +J -H M O a o u tn e w •H c m tn U o 0) £! O fO -P -P <: o (D e :3 to ■p o EH QJ Si +J O -P G 0) U U Q) O •H 1 o Si -p ^ 0) ^ o •H -P ^ I CUdP O 0) ^^ (N XJ 1^ T3 -p ^ 0) ^ 0) ^ u S^ G -P -- •H CI, o\o I QJ -^ Xi U G •H I O n 4:^ ■P '^ Xi G -P ^ •rH CUtif 00 Ti 4:; U G ■H I Xi CiitAO (U -^ vo t3 £1 LO in XI X! XI (0 "^ in rt) (0 (d in n in o n 00 VD n in 00 m in o (N X! (0 X3 X! XI (0 in in CN o m X! (d X! CN O (N O CN O in CN •^ •^ 00 X! X! iH iH r-t VD (d tn c m 0 cn tn QJ CO N Q) QJ W 4J 0) 0 -p -p QJ >1 -P -p >i >1 -P ^ >i 0 jG ^ >i a x: u Q. Qj Xi 0 a* p^ 0 0 CL. C 0 U tn 0 0) Xi 'O 0 >i G rH -p QJ iH j-i n3 Cn c x: Q) J2 x; >i 3 (0 u (0 U 0 U W x: m < ■p -p -p c QJ tn X! (0 X! 0) -P O 2 -83- XJ O Ti c ^ 0) •rH -p — 13 1 Q^6P a o dJ — (U '^r ^ 04 CM U) :3 en CO VD ^ en u U) r-i en a xi 0) g -H 4J -^ T5 - en 1 OjoNO •H 'S' •H o (U — .H f-l a CN T5 CO rci rH -p tr> en en !-( en 3 O 4:: (« en CJ -C rH 13 Ti a -P -- o <: Q) •H aio\o ^ 1 (U — c o u CD ^ 0 -P 4-) vo +j -P d r^ <: x: 0) u .c tn 4J IW c; -p -- (U CO O •H PjO\0 S-l 3 1 Q) --- (ii en !-l •^ T! 3 (U in UJ < X! c a r« ^ 3 4d O M s 0 4:: N CD G ■P ^ CO 0 0) iH ■H a.o\o rH JJ S rO 1 cu ^ 0 -P CN ^ M MM O ^ 1^ (Ij Eh pq y< •< Ti 0 (U 4:; Eh (Dm jc: 0 Xi Xi -P C -p -- O (U -H Cl,o\o (C N m 1 (U -- +J -H 0 0 ^ +J s 00 < -P Q) c; 'O A^ (U 4:; C fO u 0 4:^ 03 hJ M C 4-) ^ (U -H a,o\o en iw Oh 1 (U --' C 0 00 Ti 0 rH -H (U en c ■H o Xi > ISl 0 x: -H c -p ^ Q U ■H CUdP •H I (U '-' nH +J vo Ti fd cu Cn C ■H e <■^^ h:] M-l o cu x; en -P C o c ■H -H +J u 0 04 0 u cu 00 CO o o (N C0 in "^ o CM o in 00 CM in 00 00 OM CM 00 X! (0 X! Xi 43 42 00 -^ X! 42 m 42 42 X! (e3 in in CO en 00 in 00 in 0 rH 42 42 00 r^ rH rH CQ (tj CO c 0 tn en CU en t. -p 4J >i >i 4J 4:: >^ 0 x: 4::; >i &1 x: M cu Q4 4:; 0 a, cu 0 0 Q. G 0 u en 0 (U Xi Ti 0 >i C M -p Q) iH J-) nJ Cn c 4:; OJ x^ Xi >i d (0 u m u u U W X rc5 rH < -P < -p c cu en 42 ro 42 (Cj (U -P O - 84 - Adaptive Algal Forms Present, August to September, 1969 Attached forms present during the August 14 to September 11, 1969, period on glass slides tended to be resupinate, firmly attached along their broadsides. These included sheathed filaments of Phormidium tenue, colonies of Aphanocapsa delicatissima, plus those of several other blue-greens. Some resupinate single-celled forms also occurred. These included the diatom, Eunotia pectinalis, and the desmid, Cosmarium bireme . All of these resupinate forms had a distinct tendency to occur in areas of the slides which were free of debris. Frequencies for these forms were also usually higher for the edges than for the middle portion of slides. (The slide edges were generally free of debris.) The tendency of the coccoid colony of A. deliaatissima to appear only on cleared edges of slides was especially notable. Whereas the resupinate forms were associated with cleared areas of slides, other forms were present which tended to float in the debris that was associated with slides submerged for several weeks or longer. Many desmids tended to be associated with this debris. The filamentous blue-green, 0. tenuis, was the most numerous of the debris-associated forms during the 1969 summer study, In his study of the communities of algae in a Michigan river, Blum (1957) also comments upon the tendency of 0. tenuis communities to be associated with silt, with - 85 - these communities generally occurring only on silted stream bottoms during the summer season. He also notes an apparent light sensitivity by 0. tenuis in that it occurred mainly in shaded areas of the stream. Attached Algae of the Littoral Area, August, 1969 On August 14 and 24, 1969, collections were made of aquatic macrophytes in the littoral area for determi- nation of their epiphytic flora. Fuirena scirpoidea. Polygonum hirsutum, and Panicum hemitomon were collected on the earlier date from a depth of 18 inches at station 2. On all macrophytes the epiphytic flora was dominated by several unidentified species of Oedogonium . On P. hemitomon a co-dominant was Oscillatoria tenuis. In addition, the following attached species were recorded from the leaf sheath: Pleurataenia subooronulatum, Gleocystis vesiculosa, Mougeotia sp . , Spirogyra sp., Phormidium tenue, Eunotia pectinalis , Frustulia rhomhoides , and Anabaena oscillarioides A fresh water sponge was also present on some areas of the sheath and leaves. In addition to Oedogonium spp., Coleoohaete irregularis was a common attached form on the vertical sheaths of F. scirpoidea. Present on this sedge, but not as common, were the following species: G. vesiculosa, Bulbochaete sp., Helicodictyon planctonicum, Stephanoporos regularis , E. peotinalis , A. oscillarioides , Oscillatoria tenius y and Hapalosiphon fontinalis . - 86 - The sheath of Polygonum hirsutum was populated mainly by Oedogonium spp. and Oscillatoria tenius with Oedogonium spp. the .more abundant of the two. Present also were: G. vesiculosa, F. rhomhoides , and A. oscil- lavioides . On August 24, 1969, collections were made from station 1 of S. maovophyllum and of Fuirena sairpoidea and from station 3 of W. submersa. S. maovophyllum and F. soirpoidea were collected from an open area of the littoral zone while W. submersa was harvested from a protected plastic enclosure (Figure 6) . All substrates were taken from depths of 18 inches. Little similarity was seen between the ephiphytic communities of the 3 macrophytes . Nor did the species composition of the communities of attached algae in the limnetic area resemble that of the aquatic macrophytes, although the seeding units which populated limnetic area slides undoubtedly came from epiphytic and epipelic communities in the littoral area. The dominant epiphytes present on S. maovophyllum were Spivogyva sp., Osoillatovia tenuis, A. osoillavioides , and Fvustulia vhomboides . Many aseriate packets of Cyanophyte cells, a morphological form assumed to be a number of the Nostocaceae, were also present. Other less numerous epiphytes present included: Oedogonium sp.. - 87 - Mougeotia sp. , Euastrum binale , Eunotia peatinalis , and H. fontinalis . Fewer species were present on Fuivena soirpoidea (station 1) than on S. macrophyllum (station 1). Scrapings from the sheath encircling the stem contained mainly the coccoid Chlorophyte, G. vesiculosa. Other epiphytes present were Oedogonium spp. , Mougeotia sp. , Coleoahaete irregularis , Staurastrum paradoxum , Staurastrum sp. , and Microspora tumidula. A fresh water sponge was also attached in some areas of the sheath. A number of species were present as epiphytes on W. submersa , many of which were desraids. Desmids, in fact, dominated the epiphytic flora and included: Cloeterium intermedium , Cl, intermedium var. hibernioum , and Cl. libellula var. angusticeps . In addition several desmids occurred which were not dominants. In this latter group were: Closterium incurvum , Cl. naviaula , Desmidium baileyi , Actinotaenium cruaiferum, Arthrodesmus incus, A. octocornis , Netrium digitus , Euastrum ciastonii , Xanthidium antilopaeum var. minneapoliense , Cosmarium ornatum , C. bireme , C. blyttii , C. pyramidatum and Pleurotaenium minutum . Besides desmids, other epiphytes on W. submersa were Bulbochaete sp. , Oedogonium spp., Co leochaete irregularis , G. vesiculosa , E. pectinalis , and Nitschia palea. 88 Planktonia Algae, August to September^ 1969 Two vertical plankton tows were made in the limnetic area of Lake Mize at station 4 during the 1969 summer studies. From a tow made on August 28, the following species were identified: Eudorina elegans , Peridinium westii , and Gonyostomum semen. P. westii was the most abundant of the three. On September 11, the most abundant planktonic species was G. semen. Mallomonas caudata and P. westii were also present. In addition to planktonic algae, a number of copepods , cladocerans, and rotifers were also present in the two plankton samples. Attached Algae Present in the Limnetic Area of Lake Mize, August, 1970 Glass slides and the aquatic macrophyte, Websteria submersa, were used to study the attached algae of the limnetic area of Lake Mize during August, 1970. Collec- tions of slides and plants were made on, August 13, after 3 weeks' exposure and on August 19, after 4 weeks' exposure. Seventeen species were identified on glass and 25 on W. submersa . On both substrates, the majority of species present were Chlorophytes. A desmid, Cosmarium vegnellii , and a diatom, Eunotia pectinalis , were the dominant species present on glass. These two species were also among the dominants present on W. submersa. - 89 - In addition, Mougeotia sp. , Oedogonium spp. , Anahaena oscillarioides , and Hapalosiphon fontinalis were abundant as epiphytes on W. suhmersa at one or more depths. Vertical Distribution of Attached Algae and Other Periphyton on Glass Slides, August, 1970 During the summer study, as in previous studies, the different algal divisions and species had different vertical ranges in Lake Mize. These vertical ranges were frequently overlapping, however, as was the case with Cosmarium regnellii and Eunotia pectinalis . These two algae were commonly found together on slides suspended at 6 and 18 inches, sometimes reaching abundant frequen- cies at these depths. The vertical range of E. pectinalis generally extended deeper than that of C. regnellii. Although it was either rare or absent in collections made during most of the study period, C. regnellii was one of the most abundant epiphytes in Lake Mize during August, 1970. Unlike most desmids , which are debris-associated forms of the metaplankton, C. regnellii attached broadside to the substrate. On slides exposed for 3 weeks, the highest frequencies of C. regnellii occurred on slides suspended at a depth of 18 inches. At this level, C. regnellii was abundant and made up a larger proportion of the periphyton than any other alga (see Table 19). C. regnellii occurred - 90 - TABLE 19 Dominant Algal Species Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 Percent of Total Attached Organisms 6-inch depth 18-inch depth 30-inch depth 42-inch depth Chlorophytes Cosmarium regne llii 15 ab. Chrysophytes Eunotia peatinalis 33 Rhipidodendron splendidum (heterotroph- ic) ab. 12 Pyrrophytes Peridinium westii Other Algae 6 6 6 7 9 3 11 1 Note; ab. = absent 91 - only infrequently on slides suspended at 6 inches, the depth at which maximum frequencies of Chlorophytes on glass slides usually occurred. This species was rare at 30 inches and absent at 42 inches on 3 -week slides. The frequency pattern of C. regnellii at various depths was altogether different on slides exposed for 4 weeks as compared to those exposed for 3 weeks. While maximum frequencies occurred at 18 inches on slides exposed for 3 weeks, the maximum occurred at 6 inches on slides exposed for 4 weeks (Figures 13 and 14) . Propor- tionally, C. regnellii also made up a large share of the periphyton on 6-inch slides. At other levels, it made up comparatively little of the periphyton (Table 20) . In addition to Cosmarium regnellii , six other Chlorophytes were also present. These included: Staurastrum setigerum , Closterium naviaula , Protoderma viride , Coleoahaete irregularis , Staurastrum sp. , and Oedogonium sp. All were rare on slides at 6 and 18 inches and were generally absent at depths below 18 inches. During August, 1970, E. peatinalis was the most frequently occurring Chrysophyte at most depths. On slides exposed for 3 weeks it was common at 6 and 18 inches, with its frequency dropping to rare at depths of 30 and 42 inches. The frequency pattern of E. - 92 - U3 (D o c •H P Frequency: 1 unit = 3,000 cells, filaments of colonies per square centimeter Frequency: 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 13. Frequencies of dominant algal species and the major groups of attached organisms present on glass slides suspended in the limnetic area of Lake Mize for 3 weeks, July 23 to August 13, 1970. - 93 - u •H -P Q 18-^ 30 42 T H ( 1 h E o s o o H h M « « o s 3 PCI H 1 1 V- Frequency ; 1 unit = 3,000 cells, filaments, or colonies per square centimeter -i — f- 0) u 18 4-) 0) Q 30 — 42 to n3 O N o -p o u u Frequency ; 1 unit ^ 3,000 cells, filaments, or colonies per square centimeter Figure 14, Frequencies of dominant algal species and the various groups of attached organisms present on glass slides suspended in the limnetic area of Lake Mize for 4 weeks, July 23 to August 20, 1970. - 94 - TABLE 20 Dominant Algal Species Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 Percent of Total Attached Organisms 6-inch 18-inch 30-inch 42-inch depth depth depth depth (%) (%) (%) (%) Chlorophytes Cosmarium vegneZlii 33 Chrysophytes Eunotia pectinalis 7 3 4 4 Dinobryon caloiforme ab. 22 17 4 Rhipidodendron sptendidum (heterotroph- ic) 1 11 <1 <1 Other Algae 2 8 12 8 Note: ab. = absent - 95 - peatinalis changed somewhat on slides exposed for 4 weeks where decreases in frequencies occurred at each of the 3 lower levels as compared to slides exposed for 3 weeks. E. peatinalis was infrequent on slides at each of these depths. At 6 inches beneath the surface E. peotinalis had a frequency comparable to that observed for the optimum period of 3 weeks (Figures 13 and 14). Other Chrysophytes present included Fvustulia rhomboides , Dinobvyon oalaiforme , Rhipidodendron splendidum, and Synura sphagnioola (planktonic) . Both the attached form, P. rhomboides , and the planktonic form, S. sphagnioola , showed comparable vertical distributions on slides in the upper 42 inches of the lake, tending to occur rarely on all slides at all depths. D. oalaiforme and R. splendidum had higher frequencies at some depths than at others. The heterotrophic alga, R. splendidum, had a distinctive frequency curve which showed maximum frequencies at 30 inches on slides exposed for 3 weeks and at 18 inches on slides exposed for 4 weeks. R. splendidum was infrequent on the former (30 inches/3 weeks) and common on the latter (18 inches/ 4 weeks) . In slide samples collected from other depths on both dates, this alga was only rarely present. These frequencies during August, 1970, were also the highest - 96 - recorded during the study period for R. splendidum. Only an occasional specimen was found in collections made at other times. D. calciforme was infrequent on slides exposed for 3 weeks at the 30-inch depth and was absent at other depths. However, by the end of the 4-week exposure period, D. calciforme had become abundant on 18-inch slides where it was present in greater numbers than any other alga (see Table 20). The individually attached cells of D. calciforme also occurred infrequently at 30 and 42 inches-. Proportionally, Cyanophytes were only a small part of the algal flora of limnetic area slides during August, 1970 (Tables 21 and 22). Two species were present, Anabaena oscillarioides and Hapalo siphon fontinalis . Both occurred rarely to infrequently on 6^ and 18-inch slides with 3 weeks' exposure. A few filaments of A. oscillarioides were also present at 30 inches. On slides exposed for 4 weeks, A. oscillarioides and H, fontinalis occurred infrequently at the 6-inch level. A. oscillarioides was also rare on 18- and 30-inch slides. A planktonic dinof lagellate, Peridinium westii, appeared on slides occurring commonly at all depths. Heterotrophs formed a conspicuous part of the periphyton on upper level limnetic slides during the - 97 - TABLE 21 Proportions of Algal Divisions and Other Groups of Organisms Present on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 Percent of Total Attached Organisms ( 5-inch depth (%) 18-inch depth (%) 30-inch depth (%) I 42-inch depth (%) Algae Chlorophytes 15 19 3 <1 Chrysophytes 36 7 11 3 Cyanophytes 19 4 1 ab. Pyrrophytes 5 6 9 11 Filamentous Oomycete 36 42 <1 ab. Attached Protozoans 1 20 56 70 Rotifers ab. 1 6 14 Note ; ab. = absent - 98 - TABLE 2 2 Proportions of Algal Divisions and Other Groups of Organisms Present on Glass Slides Suspended for 4 Weeks in the Limnetic Zone of Lake Mize, July 23 to August 20, 1970 :■-■ •■:■. ■ = ■■ " -: — ~ — : — Percent of Total Number of Attached Organisms 6-inch depth (%) 18-inch depth (%) 30-inch depth (%) 42-inch depth (%) Algae Chlorophytes 42 6 2 2 Chrysophytes 7 39 25 13 Cyanophytes 3 1 3 <1 Filamentous Oomycete 37 10 1 1 Attached Protozoans 11 42 67 81 - 99 - summer of 1970 (Tables 21 and 22) . An unidentified filamentous Oomycete was abundant on 6- and 18-inch slides exposed for 3 weeks. After the 4-week exposure period, it became very abundant on 6-inch slides, remaining abundant at 18 inches. On slides exposed for both 3 and 4 weeks it was rarely seen at 30 inches and was entirely absent at 42 inches. Several genera of Vorticelloids were also prominent on slides during this period. These generally had frequencies which increased with depth in the upper 42 inches of the lake with the largest increase occurring between 6 and 18 inches. Variations with Time in the Algal Flora Present on Limnetic Area Slides, August, 1970 When slides collected on August 13, 1970, after 3 weeks' exposure, were compared with those collected on August 20, 1970, after 4 weeks' exposure, the species present and the dominants were much the same . At some depths differences in proportions at the specific level occurred between the two dates. Generally, the frequency of Chlorophytes decreased between August 13 and August 20 on slides suspended at 18 inches or below, while Chrysophytes increased slightly at depths of 30 and 42 inches . - 100 - Vert-ical Distribution Patterns of Attached Algae and Other Periphyton on Websteria submersUj August^ 1970 Two general types of algal communities were present on Websteria submersa . The epiphytes on upper level W. submersa (6 and 18 inches) were organized into a complex, somewhat stratified community. In this community, closely adhering, resupinate forms made up the level closest to the raacrophyte. Filaments projecting above the resupinate forms made up the second level. Debris and debris-associated species were then intermingled with the filaments. The communities present at 30 and 42 inches were less stratified, dominated by resupinate forms and resembling the communities found on glass slides suspended at 6 and 18 inches. Generally, W. submersa was much more densely populated by attached forms than in the case of glass slides. Counts of individual organisms were 6 to 20 times higher on W. submersa than on glass slides at the same depth. Maximum frequency of organisms on W. submersa occurred on plants submerged at either 18 or 30 inches as compared to 6 to 18 inches for glass slides. Species diversity was greatest at the 6- and 18-inch levels for W. submersa, as with glass (Tables 23, 24, 25, and 26). A large variety of Chlorophytes , especially desmids , appeared as epiphytes on W. submersa (Tables 25 - 101 TABLE 2 3 Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 Number of Species 6-inch depth 18-inch depth 30- d( -inch 2pth 1 42- d( -inch 2pth Chlorophytes 1 5 1 Chrysophytes 4 5 4 4 Cyanophytes 2 2 1 0 Pyrrophytes 1 1 1 1 Total Algal Species 8 13 7 6 102 TABLE 24 Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Lake Mize for 4 Weeks, July 23 to August 20, 1970 Number of Species 6-inch 18-inch 30- -inch 42-inch depth depth d( 2pth depth Chlorophytes 7 6 2 3 Chrysophytes 4 5 5 6 Cyanophytes 3 1 1 1 Total Number of Species 14 12 8 10 - 103 TABLE 2 5 Number of Algal Species Present at Various Depths on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 Number of Species 6- -inch 18-inch 30-inch 42- -inch d( 2pth depth depth depth Chlorophytes 16 12 4 1 Chrysophytes 4 4 6 4 Cyanophytes 4 4 3 2 Total Number of Species 24 20 13 7 - 104 - TABLE 26 Number of Algal Species Present at Various Depths on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 Number of Spe( 3ies 6- -inch 18-inch 30- -inch 42- -inch d( epth depth d( -pth d( 2pth Chlorophytes 16 12 2 3 Chrysophytes 3 8 2 2 Cyanophytes 4 3 1 2 Total Number of Species 24 23 5 7 - 105 - share of the periphyton (Tables 27 and 28, Figure 15). The most abundant Chlorophyte was the desmid, Cosmarium regnellii (Tables 28 and 29). This desmid, also abundant on glass slides, had a tendency to form short chains while adhering closely to the substrate. Maximum frequencies of C. regnellii occurred at a depth of 18 inches after both 3- and 4-week exposure periods (see Figures 15 and 16). This alga was also very abundant in samples taken from the 6-inch depth on both August 13 and August 20. With plants exposed for 3 weeks, a sharp decline in the numbers of cells of C. regnellii occurred between 18 inches (point of maximum frequency) and 30 inches. Considerable growth of C. regnellii occurred at the 30-inch depth between August 13 and August 20 so that on W. submersa exposed for weeks at this depth, C. regnellii was very abundant. Frequencies then dropped to rare at 42 inches. A second desmid which was sometimes present as an epiphyte on W. submersa was Closterium navioula. While the frequencies of this alga did not approach those of Cosmarium regnellii , it was nevertheless abundant at some depths. Generally, highest frequencies occurred at 18 inches, as in the case of Cosmarium regnellii . At 6-inch depths, Closterium navioula was also abundant. - 106 - c •H c -H +j a. 0) Q 18 — 30 42 — Frequency; 1 unit = 3,000 cells, filaments, or colonies per square centimeter CO u Q 18+ g^ o 42-1-^ s •^ s •ri -5^ r~i ^ V~i a <» E e w ■s^ o Q) ^\ '^ ^ ^ ^ ' ' ' ' I — \ — I I I ' I I I I I I I I I I I I I I I — ' Frequency 1 unit = 3,000 cells, filaments, or colonies per square centimeter Figure 15. Frequencies of dominant algal species present on Websteria submersa suspended in the limnetic area of Lake Mize for 3 weeks, July 23 to August 13, 1970. - 107 - Frequency 1 unit = 3,000 cells, filaments, or colonies per square centimeter OJ u c •H 4-1 Oi QJ Q 18-- 30-- 42-- Frequency : 1 unit = 3,000 cells, filaments, and colonies per square centimeter Figure 16. Frequencies of dominant algal species present on Wehstevia submersa suspended in the limnetic area of Lake Mize for 4 weeks, July 23 to August 20, 1970. - 108 - TABLE 2 7 Proportions of Algal Divisions Present on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 ■ ■■: ; . : :=■■..= :: Percent of the Total Number Attached Organisms of 6-inch 18-inch depth depth (%) (%) 30-inch depth (%) 42-inch depth (%) Chlorophytes Chlorophytes 65 46 15 1 Chrysophytes 9 17 14 16 Cyanophytes 24 9 3 2 - 109 - TABLE 28 Proportions of Algal Divisions and Attached Protozoa Present on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 Percent of Total Attached Organisms 6-inch depth (%) 18-inch depth (%) 30-inch depth (%) 42-inch depth (%) Algae Chlorophytes 44 68 27 2 Chrysophytes 7 30 72 57 Cyanophytes 45 2 1 1 Attached Protozoans <1 <1 <1 1 -110- TABLE 29 Dominant Algal Species Found on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 3 Weeks, July 23 to August 13, 1970 Percent of the Total Number Attached Organisms of 6-inch depth (%) 12-inch depth (%) 30-inch depth (%) 42-inch depth (%) Chlorophytes Cosmarium regnel Hi 40 36 12 <1 Mougeotia sp. 11 3 <1 ab. Chrysophytes Eunotia peotinalis 5 13 14 7 Cyanophytes Anabaena osaillarioides 11 3 1 1 Hapalosiphon fontinalis 10 1 ab. ab. Other Algae 21 11 9 14 Attached Protozoans 2 25 62 75 Note: ab. = absent - Ill - TABLE 30 Dominant Algal Species Found on Websteria submersa Suspended in the Limnetic Zone of Lake Mize for 4 Weeks, July 23 to August 20, 1970 Percent of the Total Number of Attached Organisms 6-inch depth (%) 18-inch depth (%) 30-inch depth (%) 42-inch depth (%) Chlorophytes Cosmarium vegne ZZii- 27 48 26 Chrysophytes Eunotva ■peotinalis 5 27 72 52 Cyanophytes Anabaena Oscillarioides 33 <1 ab. ab. H ap at o siphon fontinalis 11 <1 ab. ab. Other Algae 12 11 1 9 Note: ab. = absent - 112 - At 30 and 42 inches, it was rare or absent (see Figures 15 and 16) . This desmid was usually a resupinate form which appeared to adhere closely to the substrate. Sometimes it was associated loosely with the substrate or with debris. In addition to Cosmariwn regnellii and Closterium naviaula, many other desmids were also present in the limnetic area on W. submersa. These included: Cosmarium amoenum , C. pyramidatum , C. bireme , Staurastrum setigerum , S. orbiculare , Closterium libeltula , Euastrum binale , Onahyonema laeve var. latum, and Bambusiana brebissonnii . All of these were metaplanktonic forms which were loosely associated with the substrate or with debris, rather than closely adhering to a surface. C. pyramidatum , S. setigerum , and S. orbiculare were all common epiphytes of VI. submersa at the 6-inch level, after 3 weeks' exposure of the macrophytes. Each of the three desmids was infrequent at 18 inches and rare or absent at deeper levels. The other desmids listed above were all rare to infrequent at depths of 6 and/or 18 inches. Filamentous Chlorophytes which attached to y. submersa included an undetermined species of Mougeotia and three undetermined species of Oedogonium. Numeri- cally, filamentous Chlorophytes did not form as large a - 113- proportion of the periphyton as did several of the single-celled desmids. However, the tangled mass of filaments had an important structural role in the epiphytic communities by providing a means of entrapment and reten- tion for loosely associated desmids and blue-greens. Mougeotia sp. was the most abundant of the filamentous Chlorophytes. It was very abundant at the 6-inch level after both 3 and 4 weeks' exposure. At other levels, Mougeotia sp. was rare to infrequent. Oedogonium spp. occurred infrequently at 6 and 18 inches after 3 and 4 weeks. These species of Oedogonium were totally absent at greater depths. Two large prostrate Chlorophytes, Protoderma viride and Coleochaete irregularis , also occurred rarely on W. submersa suspended at 6 or 18 inches. These algal epiphytes were never found to be abundant on the filamentous W. submersa, although high frequencies sometimes occurred on littoral area slides and on broad- leaved aquatic macrophytes. Eunotia peotinalis was the dominant Chrysophyte present on W. submersa during August, 1970. Maximum frequencies of this alga occurred at the 18-inch depth on plants exposed for 3 weeks with common frequencies recorded for 6, 30, and 42 inches. On plants exposed for 114 - 4 weeks, maximum frequencies were at the 30-inch depth. E. peotinalis was then very abundant at 18 and 42 inches and common at 6 inches. It was, by far, the dominant alga on plants submerged at 30 and 42 inches with a vertical range extending deeper than that of desmids, filamentous Chlorophytes , or blue-greens. Other Chrysophytes which were epiphytes or were associated with W. submersa included: Dinobryon oytindricum (planktonic) , Synura sphagnicola (planktonic) , Frustutia rhomboides , Dinobryon aalai forme , and Rhipidodendron sptendidum . D. aalaiforme and the planktonic S. sphagnicola occurred rarely throughout the entire vertical range of 42 inches. R. sptendidum was absent from all depths except 42 inches, where it was a rare epiphyte with frequencies much below those which had been recorded from glass slides. F. rhomboides occurred irregularly (rare to common) on W. submersa at all depths. Occasionally it was absent. The planktonic, D. cylindrioum , was associated with W. submersa exposed for 3 weeks at all depths. This species was rare to abundant. It was not unusual for planktonic forms to become associated with or trapped by communities of attached algae. For such planktonic forms, bimodal or "hourglass- type" frequency diagrams were representative. - 115 - e.g., Figure 15. (A few attached forms, as F. rhomboides, also sometimes had bimodal frequency diagrams.) Planktonic dinof lagellates , frequently found on submerged glass slides, were not usually associated with W. submersa and other aquatic macrophytes in Lake Mize. During August, 19 69, the vertical range of the dominant Cyanophytes on glass slides {Phormidium tenue and Oscillatoria tenuis) extended to a depth of 66 inches. During August, 1970, the vertical range of the dominant blue-green epiphytes of W. submersa was quite reduced in comparison. Both Hapalosiphon fontinalis and Anabaena osaillarioides occurred almost exclusively at the 6-inch depth on W. submersa. At the 6-inch depth they were each abundant to very abundant. At 18 inches, only a few specimens were found (Figures 15 and 16) . Both species were absent at 30 and 42 inches. (They also occurred mainly at the 6-inch depth on glass slides where they were much less abundant than on W. submersa, cf. . p. 94). The attaching forms of these two blue-greens were usually different. The branched filaments of H. fontinalis were tightly attached to the substrate. In contrast, the filaments of A. osaillarioides were usually locsely associated or intermingled with the vertical filaments of both Mougeotia sp. and other Chlorophytes. - 116 - A. osaillarioides was also observed at times adhering to the substrate in a prostrate position. Variations with Time in the Algal Flora Present on Websteria submersa^ August^ 1970 When the Websteria submersa collected on August 13, 1970 (3 weeks' exposure) was compared with that collected on August 20, 1970 (4 weeks' exposure), certain differences became apparent, particularly at the depths of 6 and 30 inches. At 6 inches, an increase in Cyanophytes occurred especially in the number of filaments of Anabaena osaillarioides . Many of the filaments on August 20 were short, the product of a recently germinated akinete. There were also a number of akinetes present. The increase in A. osaillarioides was accompanied also by an increase in Cosmarium regnellii . At 30 inches, an increase in populations of Eunotia peotinalis occurred between August 13 and August 20 (see Figures 15 and 16) . At other depths, frequencies and proportions of most algae showed little change over the 7-day period. Nor did frequencies of Mougeotia sp. and E. peatinalis change significantly at the 6-inch depth. The number of species at all depths was also similar on August 13 and August 20 (Tables 25 and 26) , although some of the rare - 117 - species were different. At the upper levels (6 and 18 inches), these rare species were mainly desmids. Comparison: Algal Flora of Glass Slides and of Websteria submersa, August, 1970 The community of attached algae on glass slides and on Websteria submersa during August, 1970, contained many of the same species. Some dominants were also the same. However, marked differences were observed in the proportions and frequencies of algal species on the two substrates. Higher frequencies were recorded for most species of algae on W. submersa than on glass slides. Desmids, filamentous Chlorophytes, and blue-green algae also formed larger proportions of the periphyton on W. submersa than on glass slides. 9 The desmid, Cosmarium regneltii , was a major component in the algal flora of both glass slides and W. submersa. At all depths higher frequencies of this desmid were recorded on W. submersa than on glass slides (Table 31) . These differences were especially evident on substrates submerged at depths of 18 and 3 0 inches. On August 20, 197 0, there were approximately 100 times as many cells of C. regnellii present on W. submersa, suspended at a depth of 6 inches, as on glass slides. And, at 30 inches, there were over 150 times as many cells of this alga on W. submersa as on glass slides. - 118 - Q) ^ +> fl 0 T} - G W (0 M (U in (U (U S ^3 •H n iH n5 to ^ 'd 0) -H U5 -P !-l W M-l O ^ (d nj rH c -H Pm O o - e o •» 6 fQ r- 0) 0 i tp 0 13 rH d c -id rH <; (U d C rO C X! m u c 0 «: •HON " +J II 4-1 M ^ 0 c 0) « -H < OJ > CO 4J d S^ Q) ^ rr C 03 C -P 0) 0 E g c; Sh rC! -H m HH +J S iJ Ti c fi W C M Q) (U d QJ -^ 4-1 ^ II u ?^ H & i +i -H !h (d to (U H t^ c > 0 ■» 0 rH 1^ -rl II fa w ^ c <: rH +J (0 c; D4^ tn (t3 in rH rH d <: CL, m MH u 0 ■r^ -p fl (0 0 d in w •H ri: Sh ni a, e 0 0 •vi !i. W m 4^ tt) CO J3 rCl 0 Ml C LS H CN M- 01 en rd o « •rJ !i< W in HJ Q) CO x; ^ 0 W c LS M 0 ro UI Ifl (C o « •t^ i^ W U) -U Q) CO s: ^ 0 w c ;s: H 00 •-t en CO ro o (» en CO u :^ c ^D tn en rH (>i Pi H u c; a; a: rt pi; cc: « > -< sC CO ^-^ ;:r^ & G <~-i « "TS 3 r~i ro s ii a, s !n Vi +i i--i jij 3 a • •<~i fi •t^ Ci s G ri. +i in a, ■H ;i K •r^ K cn a in w G) •^ U u « e in 4^ x; « tT> g , — « g rC U fiC H (X o s to -P rs Q) (0 -a u o 2 Si s to OJ u •^ U-l to <2 (0 to to to <3 Co > u i to U-l Co w to <3 CO m Q) 4J x: w >, u - 120 - « •r^ !^ ^ m •^ D [/) U) fO u u u q; 05 u « •XI T) M u «! 'TTJ 4J ca (d S" to to E -H « T) Q^ u C\i S H S >-i <3 t-^ to O '« ■rH ,0 -H 5 (0 r~-^ i~">, •^•§ •r^ C ^•H -W -H O to O « 0 •^ K to iH O « (U ri-) O H O SlH •^i s; M fO P M l-i ^^ !^ -H s o O S 0) a c S ffi CJ> ^ -w cc; .^ O TS ^ J^ (fl a ^-^ rs; s CO — , ^ ^~* s g 3 s • -d El, w a. • « to • « x; S « g to 'CI c N •tJ Xi S;) u tn s> 6 3 ^1 •H « -p I~-i u "3 ?H fO -< !^ 0) Fi O 'ti ^ ^ s S •f^ s 2 •t^ "ri 3^ A;" s JL o Cl CO u:; b) U^ to +J o u u >1 04 to <» 3 0) s ft. to 0) +J >i c >1 u -M c Q) O s e s; o x: en a 0) 2 - 121 - « •rJ ^ W tn -U 0) CO -C rQ t) w c IS M CN ■^ w tn ra o Q) V) +i Q) CO Xi rC) C) c\^ C IS H o n tn Ul (0 (J « •v-i Ss w m +:> OJ CO J= .Q C) W c rs M CO •H w m (0 o « •(^ i^H v« +i tn CO (1) rCl ,C w u Is c H 1^ tn tn ftJ o \D H t-~ H H rt cn u u o CM M « IN < < CN H \£> CO CO Q) •jJ ■13 »~-i § M M 1-1 tn ^ 0 (U t-i O 4-1 M U ti CO • (0 t» u O tr> -P « 0 t o o 4-) ip o o o >i o tj ^ C CN (U 3 M-l !J< O OJ u >, tp u a tn D^ ■P tu c s^ 0) ip tn 0) (TJ p Ot VI 1) -p tu tn i 3 >i o U rP c Q) IP o 3 ip (1) rfl p MH tn > (0 >1 u c 0) 3 D< OJ p ip -p G OJ tn tn rfl P Q) p tn a +J - c OJ tn 0) (U P s * ^ p a, -- tu H p --- ^ +i tn (U p ft (1) p O CO g ,!^ ca r*^ L^^ ^ to i-H cc; - 122 - A number of other desmids, rare or absent on glass, were also associated with W . submersa (Table 31) . Stauvastrum setigevum was a common epiphyte on 6-inch W. submersa on August 13. It was rarely present on glass slides. Also, on August 13, Cosmarium pyramidatum was abundant on W. submersa but was absent from glass. Altogether, 13 desmid species occurred as epiphytes on fv'. submersa while 5 species were associated with glass slides on August 13. Data for August 20 were similar. Filamentous Chlorophytes also occurred more frequently on W. submersa than on glass slides. Mougeotia sp. was absent on glass slides during August, 1970. Yet, on both August 13 and August 20, 1970, this species was very abundant on W. submersa at 6 inches. [Mougeotia sp. did occur on glass slides during January, 1969, cf. p. 57). Differences were also observed in the frequency of blue-green algae on glass slides and on W . submersa as has been mentioned previously. At 6 inches, blue- green algae were infrequent on glass slides; however, Hapalosiphon fontinalis was abundant and Anabaena oscillarioides was very abundant on W. submersa suspended at 6 inches. As with Chlorophytes and Cyanophytes, higher numbers of most Chrysophyte species occurred on W. - 123 - submersa than on glass slides (Table 31). These differences were especially obvious at depths of 18, 30, and 42 inches. One common species on both glass and on W. submersa was the diatom, Eunotia peotinalis . This species always had higher frequencies on W. submersa than on glass slides. This difference may be illustrated by two examples. On August 20, 1970, 65 times as many cells of E. peotinalis occurred on f/. submersa as on glass at 18 inches. And, at 30 inches, the difference in cell density, f/efcs terta/glass increased to 200/1. While higher diatom frequencies occurred on W. submersa, in contrast, the heterotrophic Chrysophyte , Rhipidodendron splendidum, reached a higher frequency on glass. This alga was only rarely found at 42 inches as an epiphyte on W. submersa. However, it was a common attached form on glass slides suspended at some depths. Several other categories of organisms were more abundant on glass slides than on W. submersa. Most planktonic algae were more abundant on glass, and a filamentous Phycomycete was abundant to very abundant on upper level slides (6 and 18 inches) but was rare on W. submersa . Planktonic Algae, August 13, 1970 Two algal species were identified from a vertical plankton tow in the limnetic area of Lake Mize - 12 4 - on August, 1970. These were Peridinium westii and Stephanoporos regularis , the former being more abundant than the latter. Both of these species were also some- times present in the periphyton during August, 197 0. As previously mentioned, planktonic species in Lake Mize were more commonly trapped by the periphyton of slides than that of aquatic macrophytes. Attached Algae of the Littoral Area, August, 1970 A study of the attached algae present in the littoral area of Lake Mize was undertaken during August, 1970, to parallel the limnetic area studies carried out at the same time. Slides and aquatic macrophytes were collected from glass and plastic enclosures at station 1 on August 15. On August 20, collections of slides and plants were also made from a glass enclosure at station 2. In each case, substrates were submerged at a depth of 18 inches and collected after an exposure period of 4 weeks. Plants and slides from open areas of the littoral zone were also gathered on these two dates. In addition, collections were made of glass and plastic slides suspended in an area of the littoral zone near station 1 which was exposed to currents. These slides were submerged at the depth of 18 inches from April 30, 1970, to August 20, 1970. - 125 - As during previous littoral studies, diverse coinmunities of attached algae were found on the different plants and slides collected during August, 1970. Floristic composition varied from one area of the lake to another and even from one slide to another in the same area. While some species were broadly distributed over the lake, others were confined to specific locations or were more abundant in some parts of the lake than in others. Although no substrate specificity by any algal species could be demonstrated, frequencies and relative proportions of various algae were dissimilar on different plants and on artificial substrates used, e.g., glass and plastic. (Some harvested plants were exposed for a measured period. For others, which grew naturally in the lake, recording of the exposure period was not possible.) Several differences were evident in comparing the periphyton on slides at stations 1, 2, and 4 submerged at the same depth (18 inches) . Slides in the littoral area (stations 1 and 2) showed a total organism frequency which differed little from the organism frequency on slides at the 18" inch level in the limnetic area (station 4) . However, 40% of the organisms on slides in the limnetic area were protozoans and fungi. In the littoral area, most attaching forms were algae. Proto- zoans and fungi together constituted less than 1% of the - 126 - attached biota. Other differences were also apparent. The spreading, prostrate alga, Protoderma vivide, was common on slides at both stations in the littoral area. It did not appear on glass slides in the limnetic area. Another prostrate alga, Coleochaete irregularis , was common on glass slides at station 2. It was rare to infrequent on plastic slides submerged in the limnetic area, but was not present on glass slides at either station 1 (littoral) or station 4 (limnetic) . Chlorophytes were generally more abundant on littoral area slides than on limnetic area slides, although many of the species present were the same. Cosmarium regnellii was a widely distributed attached species in Lake Mize during August, 1970. At 18 inches in the limnetic area, it was infrequent on glass slides. It was over 10 as times abundant on glass slides in a protected enclosure at station 1 than on 18- inch limnetic area slides. At station 2, frequencies of C. regnellii were not as high as at station 1, although it remained abundant. Blue-greens were also more abundant on littoral area slides than on limnetic area slides. As with the prostrate green species, differences also occurred between stations 1 and 2. One species, Anabaena oscillarioides , occurred rarely on 18- inch slides in the - 127 - limnetic area. This species was also rare at station 1. It did not appear on slides at station 2. At station 1, two closely adhering, filamentous forms, Lynbya novdgaardii, and Hapalosiphon fontinalis , were common on slides. At station 2, L. nordgaardii was rare while H. fontinalis was abundant. Both L. nordgaardii and H. fontinalis were absent on limnetic area slides at this depth. Dinobryon aalciforme and Rhipidodendron splendidum were rare on slides at both littoral stations. On 18- inch slides in the limnetic area the former was abundant and the latter common. Attached Algae on Glass and Plastio Slides, Littoral Area, August, 1970 The glass and plastic slides submerged at a depth of 18 inches in an exposed area of the littoral zone from April 30, 1970, to August 15, 1970, had a flora dominated by diatoms. Eunotia peotinalis , E. vanheurakia var. intermedia, and E. zygodon were the most abundant species. A significant difference occurred in the frequency of these 3 diatoms on glass and plastic. Collectively, they were 5 times as frequent on plastic as on glass. Total organism frequency, as well as the number of species, was also higher on plastic (see Tables 32 and 33) . However, species diversity on neither - 123 - W (U U) O Oj *• X M W (D w o Ti H -H iH 00 W rH U M-l •H O -P CO 'd c CO tn H O O o ^ r- 0 Q - o (0 (N -P TJ (0 C fO Q) N in ■H ,H in iM 0) S-l &4 O 'T3 (1) 0) <: •H O r-i C/3 O -P M +J IW -P -p o O U g 2 •H tn 0) •H o in o u Q) Xi w (1) (tJ xi 0) -H >-l rH en fO 'd u •H <: rH cn en tn o td Oj r-l X O w o O cr> -P .H o «- cn o CN nH •H -p s-l tn a, Hi o tn (U cTi (U S-l O rH T3 <; -p -H iH 13 00 IT) CO Q) iH rH ■P tn u >i-P tn (U rH cn (0 -P 3 3 O 1-0 Cr> 04 <: O ro »* CN CN ^ 00 in n CN CN cn Q) •H O CU cu cn U-l 0 tn cn tn u 0) (U tn 0) 0) +J -P 0) -P ^ >i >i 4J >i ^ ^ j:^ >i -C ^ Oi a ^ a. s 0 O Oi 0 M tn 0 x: rH 0 >i c -p rt3 rH U (0 c -P Xi Xi >. (t3 O u u o X B - 129 - o in in r- e Q) a o rH Q r^ tP CO TJ fN 0) tu ^ Sh O crv CO dJ rH O u (0 O ro iH w tn -H 4J C !^ W 0 M (fi o o o 0 -P ^ (U to ft ft 3 (N o o to o ft rH X <: in m o 4-) (N aw 0 - "• C i << in VD H 0 r-H t-P rH U rH •rl MH u o nH M t! tn Qj rH en O o O o (T5 < 0) (0 -P P p o o in o tJi -P rH 0 1^ tJ^ VD m vo n rH nH U O M 13 ^ •• ^ ^ < to (U CM < CM r^ rH n U rH r-t -POM C -P 0 to -P u C -H •^ >i •H ^q •v^ •l:^ U e r-i •^ C 0 0) f~i ^ 0) Q ^ (» ?s 13 -p S « cr IW <35 « 0) 0 C Q) • t35 Sh •H ?H ft '^ t, m ft S^ Q) s> to d X >1 S >i O -P rC! Cn cri w ^ tQ X S >i S U (U ft Q ft S X S) O M o H 0 rH Xi u tn >i u Xi o 0 to >1 rH to -P 0 - 130 - plastic nor glass in the area exposed to currents was as high as that on glass in protected areas at stations 1 and 2. Total organism frequency on glass in the 3 areas was similar. The macrophytes submerged in a plastic enclosure for 4 weeks at station 1 included W. submersa and S. maorophyllum . Several naturally growing plants were also collected on August 15 from a depth of 18 inches. These included Utrioularia olivacea , Panioum hemitomon and Polygonum hirsutum . The most abundant epiphytic species appearing on W. submersa at station 1 after 4 weeks' exposure were Cosmarium vegnellii , Ctosterium navicula, Mougeotia sp., and Eunotia pectinalis . Frequencies of the two tightly adhering dominants, C. vegnellii and E. peatinalis , and the filamentous Mougeotia sp. were comparable to those on 18-inch limnetic W. submersa while frequencies of the loosely associated CI. navicula and Anabaena oscillarioides were not the same on 18-inch limnetic and littoral f/, submersa . Cl. navicula was 5 times more abundant and A. oscillarioides was 20 times more abundant in the littoral area at 18 inches than in the limnetic area at the same depth. All five dominants had higher frequencies on littoral W. submersa than on vertically positioned glass - 131 - slides in the same enclosure. C. regnellii was over 10 times as abundant on W. submersa as on glass while Cl. naviaula was 70 times more frequent on W. submersa as on glass slides. A. oscillarioides and Mougeotia sp. were both abundant on W. submersa while occurring only rarely on glass. The other epiphytic algae present from the littoral area are listed in Table 34. Generally, the broad, prostrate greens common on glass were rare on W. submersa. Several other algae, including the small Chrysophyte, Peroniella planctonica , were also more abundant on glass than on the filamentous f/. submersa. Sphagnum maarophyllum had a reduced algal flora as compared to that of W. submersa in the same plastic enclosure. The number of algal species appearing on the two macrophytes, however, was about the same (see Table 33) . The most abundant species occurring on S. maarophyllum were Cosmarium regnellii , Closterium naviaula , Anabaena osaillarioides , and Eunotia peatinalis. These four species were also dominants on W. submersa where frequencies were several times greater than on S. maarophyl lum . During August, 1970, tangled masses of the bladderwort, Utriaularia olivaoea, occupied much of the - 132 - en en s Q) en X} •H ■H G nH S (0 n3 cn ^ s u !T> o\o 1-^ m U tn --' TO U-l O tn S5 S-l (0 ^ d 'd rH CuW QJ o o x: 5i^ OJ u O J3 tC G 4J -p E +j ^ < S 0 s <-\ UH S (U 0 o ti^cq •vi G « M ^ 03 rs; en o 0) Q) Sh -^ cu (L) r-~ J3 +i Q) o\o <^ x: a> g 03 S -' O nH 13 rii ^Cl Ti C s c» S C H - :s 03 (0 in i-H 00 rH (C ^r-l 4-) « -u 0 03 < W Eh ^ — 3 ca iH Cn (U E 3 JH ^Q fl Cd^ *o i-q s^ en >i a « a.'^' PQ CO ~— H (U .« O < +i IK o a, Sh E-f W 0) 1-0 M ^ M c: < -H n3 -13 (U 0) ^ u u m fO rH -P 04 4J <; to (N fN rH Xi A "^ X! (0 XI CN CO X! m 00 X) X! X( XI m (0 (d nj CN X! X! (0 fN a Pu CD M E S S G PU CD CD en en !^ rCl G •ri E •t-i e/i 03 G E E 4^ G +:> E ^Q 3 S^ •^ !^ 3 S Q) E CD G G E E E 3 ^ ta HH -K> O •ri •t^ G Sh G ?H •^ 3 3 3 •r5 E -W +i 0 en 03 fX S S rs; !» rs; Sj +i •t^ •t-^ •t-i ?L, 3 03 03 Q) ;s3 03 O o O ^ o C3^ O ^ ?^ ?H ^ ?H G G U 4-1 o o !3> G> o O o O CD G G G +i -p !^ •t^ 0) >i o ?H O O rCl 4^ Cfl ?H G> E E S 03 03 3 Ss jD x: 01 ly •^ '^ tO O to M 3 03 03 03 O G G y g Ck lO •ri Q) Q) s !^ O a, O O o o lO 3 +i M 3 0 U 0 <^ :§: O O Oq ft. Co Co 5: U W — O in (T3 T! iH (D o x: u m +1 -p < M-l O a •^ « ^1 Sh CO dj Q) Sh -— ^ +i ij) dvo g w E^ :3 rQ ^Q S Q) 3 ::s « .H (C 4-) 0 Eh (U ^ -P E 3 ^-^ s r-i O s r-^ s S> — -P (33r« cW C a Cu^ Q) r^ o U Cb i^ S-i Co o QJ o (X E -Q Si (t3 n3 -Q m Xi X! V V X! ^ ^ vo n^ iH in X! X! to (0 fC (0 (t3 (0 m cs ID X3 01 CM •^ E s « 'y E CO •ri CO CO M •^3 CO Q) ^-i i 0 0 3 Cu 0 to S to X! -P CJ rCl •r^ rCl CS XI X5 4:^ s; S s •ti c 3 S ■+i e >i rs; tj 0 S a, £ n3 Qa •ri M Si ^c 3 Sh •^ •^ d x: cu s CO 35 « 3 0 Cl C5 Co Dq Cq fi^ a, fe: s Qa ^ ^ 05 1^ a^ s m 0 I* >i c OJ M 14 -P x: >1 0 u 0 3 - 134 - littoral area at station 1, extending several feet below the surface and into the perforated plastic enclosure. Usually, this macrophyte was observed only in the floating state. Samples of this filamentous aquatic plant taken from outside the plastic enclosure had a flora unlike that of other macrophytes or of glass slides at station 1. The dominants present were Eunotia zygodon, E. pectinatis , Coleochaete irregularis , and Protoderma viride. During the study period, E. zygodon was recorded as abundant only on U. olivacea, although it was sometimes rare to infrequent on other substrates. Other epiphytes which occurred on U. olivacea were Aphanochaete repens, Oedogonium spp., Gleoaystis vesiculosa, Cosmarium regnellii , Mougeotia sp. , Stephanoporos regularis , Lynbya nordgaardii , and Hapalosiphon fontinalis . Samples of U. olivacea taken from inside the plastic enclosure had an aquatic flora similar to that of the W. submersa, also inside the enclosure. The most abundant species on U. olivacea were Cosmarium regnellii, CI. navicula, Mougeotia sp., and A. osaillarioides . The other species present were Euastrum binale^ Protoderma viride, G. vesiculosa, Microspora tumidula , Onchyonema laeve var . latum, Oedogonium sp. , Bulboohaete sp., and L. nordgaardii . Both leaf and stem sheaths of Paniaum hemitomon and Polygonium hirsutum were examined for epiphytes. - 135 Oedogonium spp. was a dominant on both areas of Taniaum hemitomon with Cosmarium regneltii also a common epiphyte on the leaves, but not on the vertical, hairy sheath where it was infrequent. Most algal species occurring on P. hemitomon were present on both leaves and sheaths. These included: CZosterium naviaula , S. regutaris , Mougeotia sp. , Bulbochaete sp. , Spirogyra sp., G. vesiculosa , Nitschia palea, Frustulia rhomboides , E. peotinalis , E. zygodon , and A. osaittarioides . The hirsute leaves of Polygonum hirsutum were covered by a mucilaginous layer containing L. nordgaardii and an unidentified filamentous Oomycete. The other epiphytes present on the submerged leaves of P. hirsutum were: Cl . naviaula , Staurastrum setigevum , Cosmarium vegnellii , G. vesiculosa, Bulbochaete sp. , E, peotinalis , and H. fontinalis . Sheaths ot _ Polygonum hirsutum , which are also hirsute, were not covered by the mucilaginous layer containing L. nordgaardii and the filamentous fungus, although a few specimens of L. nordgaardii were present. Oedogonium spp. and H. fontinalis were the most abundant epiphytes with the following also recorded: 0. laeve var, latum, Closterium navicula , Cosmarium regnellii , C. amoenum, G, vesiculosa, Euastrum binale, Bulbochaete sp. , - 136 - Frustulia rhomboides , Eunotia pectinalis , E. zygodon, N. palea, and H. fontinalis. At station 2, located in a protected area of the lake, the following macrophytes were submerged at 18 inches for 4 weeks in a glass enclosure: Sphagnum macrophyllum , Baaopa caroliniana , Mayaoa aubleti , and Fuivene sairpoidea. The floating angiosperm, U. olivacea , was also gathered from the surface of the lake near the glass enclosure. S. macrophyllum had an epiphytic flora at station 2 which was dominated by C. regnellii , Oedogonium spp., and A. oscillarioides . Two of these algae (C. regnellii and A. oscillarioides) were among the dominants on S. macrophyllum at station 1. The other epiphytes present also included a number of desmids as observed at station 1. These were: Cosmarium hireme , C. pyramidatum , Onchyonema laeve var . latum, and Closterium navicula. In addition, the following epiphytes were also present: Bulhoahaete sp. , Coleochaete irregularis , Protoderma viride, Mougeotia sp. , N. palea, E. pectinalis , A. oscillarioides , and H. fontinalis . The lower leaves of B. caroliniana at station 2 had an epiphytic flora not clearly dominated by any one alga. The most numerous species included Coleochaete - 137 - irregularis , Protoderma viride, Cosmarium regnellii , C. bireme , Oedogonium sp. , E, pectinalis , and H. fontinalis . Except for Oedogonium sp. , all were resupinate forms which adhered closely to the surface of the broad, horizontally oriented leaves of B. caroliniana. Nineteen species of algae were present. In addition to the above, records show the presence of Mougeotia sp. , Closterium navicula , Euastrum binale , Cosmarium amoenum , Staurastrum setigerum , Desmidium baileyi , N. palea, F. rhomboides , and L. nordgaardii . The upper leaves of B. caroliniana were sparsely populated with only a few attached forms present. No one species was dominant as a pioneering attacher on the new leaves. Seven species of attached algae were present on M. aubleti. Oedogonium spp. , and Coleochaete irregularis were the most common epiphytes. The other species present were Mougeotia sp. , Eunotia pectinalis , A. oscillarioides , and L. nordgaardii . The dominant epiphytes were Cosmarium regnellii , E. pectinalis , and A. oscillarioides on the vertical stems of F. sairpoidea at station 2. These were all common attached species at this time on many of the aquatic macrophytes present at stations 1 and 2 and on W. submersa - 138 - artificially suspended in the limnetic area. In addition, the following were recorded from F. sairpoidea: Cosmarium bireme , C. amoenum, Mougeotia sp. , Oedogonium sp. , Protoderma vivide^ E. pectinatis , F . rhomboidesj H. fontinalis , and A. osoillarioides . Other Littoral Studies , May, 1969; July, 1969; April, 1971; July, 1971; and September, 1971 In addition to the observations of littoral algae made during August, 1969, and August, 1970, collections of aquatic macrophytes and their epiphytes were also made during May, 1969; July, 1969; April, 1971; and July, 1971. In addition, glass slides were exposed at littoral stations during the periods April to May, 1969, and August to September, 1971. Collections were made on May 9 and May 20, 1969. On May 9, collections were made from two plastic enclosures at station 2 of glass slides, of Mayaaa aubletii , of Websteria submersa , and of Sphagnum macrophyllum . All were exposed at a depth of 18 inches for 2 weeks. In the first plastic enclosure, glass slides were covered by bryozoans. Attached to the bryozoans, but not directly to the slide, was the blue-green alga, Hapalosiphon fontinalis. The dominant alga present on - 139 - slides was Phormidium tenue which occurred mainly in areas of the slides near the bryozoans. In addition, a number of desmids were present. These included Cosmarium hiveme, C. o ma turn , C. pyramidatum , Euastrum ciastonii , E. affine, Micrasterias fimbviata, Tetmemorus bvebissonii , Closterium navicula , Cl . intermedium , and Netrium digitus. Other epiphytes included Protoderma viride , Oedogonium sp. , Neidium ladogense var . densestriatum , Eunotia pectinalis , E. vanheurokia var. intermedia , Nitsahia palea, and the planktonic dinof lagellate, Peridinium limbatum, S. macrophyllum was populated by seven algal species, none of which were abundant or dominant. These included: two unidentified species of Oedogonium; the desmids, Spirotaenia aondensata, Cosmarium regnelliij C. bireme, and Closterium intermedium', and the diatom, Eunotia pectinalis . The diatoms, E. pectinalis and E. vanheurokia var. intermedia were abundant on W. submersa at station 2. In addition, the following epiphytes were present: Cosmarium bireme, C. regnellii , Oedogonium spp., and Frustulia rhomboides . Glass slides taken from the second plastic enclosure at station 2 were more densely populated than those taken from the first enclosure. Also, bryozoans - 140 - were not present as in the first enclosure. The dominant species on slides taken from the second enclosure were N . palea (diatom) and Stephanoporos regularis (Xanthophyte) . On the edges of the slides, three resupinate species, Aphanocapsa deliaatissima , P. vivide , and E. pectinalis , were abundant. The other attached species recorded from the slides were Micrasterias fimbriataj Closterium intermedium J Cl. incurvum ^ Gleooystis vesiculosa, Oedogonium sp. , Spirogyra sp. , F. rhomboides, Pinnularia gibba, and Phormidium tenue. S. macrophyllum and M, aubleti removed from the second enclosure were sparsely populated with infrequent epiphytes. The following were recorded on S. maarophyllumi Oedogonium spp. , Bulboohaete sp. , Stephanoporos regularis , Closterium inaurvum , Cosmarium bireme ^ F. rhomboides ^ N. palea, E. pectinalis , and A. deliaatissima. M. aubleti was even more sparsely populated than Sphagnum macrophyllum , having Micrasterias fimbriata, Mougeotia sp., and Spirogyra sp. as the only epiphytes. In his study of the phyco-periphyton in several oligiotrophic lakes, Foerster (1964) observed that colonization of glass slides by attached algae proceeded faster in earlier successional stages than on aquatic macrophytes. In later stages production on aquatic macrophytes exceeded that on glass slides. The present writer's study tends to confirm - 141 - these observations. Algal frequencies were greater on slides after 2 weeks' exposure during April to May, 1969, than on macrophytes. Foerster's second observation was also confirmed for the filamentous aquatic macrophytes which were present. For example, substantially greater algal frequencies were found on Websteria submersa after 3 to 4 weeks' exposure than on glass slides (cf. p. 1L6 ) . On May 20, 1969, a number of collections were made from station 3. From a glass enclosure after 6 weeks' exposure at 18 inches, W. submersa , M. aubleti, and Sphagnum maorophytlum were collected. The following naturally growing species were also collected from a depth of 18 inches at station 3: Panicum hemitomon , M. aubteti , Leersia orysoides , and Utriaularia olivaoea. W . submersa, collected from the enclosure, had the following epiphytes: Oedogonium sp., Spirogyra sp., Bulbochaete sp. , Gleocystis vesiculosa, Coleoahaete irregularis , Mougeotia sp. , Cosmarium bireme , C. pyramidatum , Desmidium baileyi , E. peotinalis , and Rhipidodendron splendidum . None were abundant. M. aubleti, also collected from the enclosure, had a somewhat different flora from that of W. submersa. Several closely appressed forms were common to abundant: Cosmarium bireme, C. regnellii , Coleoahaete irregularis , and E. peotinalis . Other epiphytes included: Oedogonium - 142 - sp. , Bulbochaete sp. , Spirogyva sp., M. fimbriata, Onohyonema laeve var . latum, E. zygodon, and A. osaillarioides . The S. macrophyltum from the enclosure had a still somewhat different algal flora. The appressed species, Cosmavium hireme and H. fontinalis , and the filamentous Oedogonium spp. were abundant. Also present were: ^seriate packets of an unidentified member of the Nostocaceae, Cosmavium ornatum , Aotinotanium eruoiferum, Closterium intermedium, G, vesiculosa, Mougeotia sp. , Bulbochaete sp., R. splendidum, Eunotia pectinalis , and F. rhomboides . The small Chrysophy te , Lagynion soherffellii, was also present as an epiphyte on a single Oedogonium species. The leaves and stems of the naturally growing grasses, Panicum hemitomon and Leersia oryzoides taken ■from station 3 on May 20, 1969, were covered by a fila- mentous mat composed of several unidentified species of Oedogonium . The other epiphytes present on the leaves of P. hemitomon were: Pleurataenia subcoronulatuw , Cosmavium py rami datum , C. blylii, C. vegnellii , Clostevium intermedium, Cl. incuvvum , Cl. libellula , Cl. setaceum , Coleoohaete irregularis , Gleocystis vesiculosa , Mougeotia sp. , E. pectinalis, A. oscillarioides , and H. fontinalis. - 143 - In addition to the leaves, several of the adventitious roots of P. hemitomon were also examined for epiphytes. These roots were filamentous, extending into the water rather than anchoring the plant. The epiphytic community present was unlike that on the leaves. Oedogonium spp. remained dominant but was not as abundant as on the broad leaves of this macrophyte. The filamentous Moug eotia sp. and several closely adhering species, Cosmarium regnellii , C. bireme, Coleochaete irregularis , and H. fontinalis , were also abundant. The other species recorded were: Pleurataenia subcoronulatum and E. pectinalis . L. oryzoides had few epiphytes besides Oedogonium spp. The other species present were Coleochaete irregularis , Mougeotia sp. , and H. fontinalis . The floating macrophyte, U. olivacea , also had an epiphytic flora dominated by Oedogonium spp. The filamen- tous desmid , Pleurataenia suhooronulatum , was a subdominant. The other epiphytes recorded were: Mougeotia sp. , Coleochaete irregularis , and H. fontinalis . At station 3, the naturally growing M. aubleti had a unique epiphytic flora as compared with the other macrophytes sampled on May 20, 1969. Two closely adhering forms Protoderma viride (Chlorophyte) and Aphanocapsa deliaatissima (Cyanophyte) were co-dominants. Also present, but not as abundant were Oedogonium spp., - 144 - G. vesiculosa , Cosmarium hireme , Aphanoohaete repens , E. peatinalis , and E. zygodon. On July 26, 1969, Panioum hemitomon (natually growing) was collected from each of the three littoral stations. In each case the portion of the plant sampled was the vertical leaf sheath. Sheaths were collected from a depth of 18 inches. At station 1, the most abundant epiphytes on the leaf sheat of P. hemitomon were the metaplanktonic Pleura- taenia subcoronulatum and four unidentified species of Oedogonium . (Many Oedogonium gerralings were present.) Coteoahaete irregularis , Cosmarium regnellii , and Oscillatoria tenuis were common epiphytic species. Other species with rare to infrequent occurrences were Mougeotia sp., Cosmarium hireme, Netrium digitus , Onohyonema laeve var. latum, Hyalotheca dissiliens , Closterium inourvum , CI. navicula , Frustulia rhomboides , E. pectinalis , E. zygodon , Nitschia palea , Stephanoporos regularis , and Anabaena osaillarioides . At station 2, Panicum hemitomon also had an algal flora dominated by Oedogonium spp. Again, many of the specimens present were germlings. Two other filamentous greens, Mougeotia sp. and Spirogyra sp., were sub-dominants Additional epiphytes present were: Closterium incurvum , - 145 - Cl. navioula, Cosmavium hiveme , C. amoenum , G. vesiculosa, Bulboohaete sp. , F. rhomboides , and E. peatinalis . The filamentous desmid, Pleurataenia subcoronulatum , abundant at station 1, was absent at station 2. The Panicum hemitomon gathered from station 3 supported an epiphytic flora dominated by Oedogonium spp. , as observed at stations 1 and 2. As at station 1, Pleurataenia subcoronulatum was a co-dominant. The other members of the epiphytic community at station 3 were: G. vesiculosa, Staurastrum paradoxum , Cosmavium ornatum , Closterium incurvum , and Onchyonema laeve var. latum. On April 30, 1971, spring winds had uprooted a portion of the aquatic macrophyte, W. submersa, so that it was present both in the rooted and floating states. Collections were made of this plant from stations 1 and 2 and at several intermediate points between the two stations. At station 1, collections were made of rooted plants from a depth of 6 inches. At station 2, floating plants were gathered as well as rooted plants from depths of 6 and 9 inches. Macrophytes collected from intermediate points were taken from depths of 6 or 9 inches. At station 1, a microscopic examination of W. submersa (depth of 6 inches) showed the macrophyte to be covered by the Xanthophyte, Stephanoporos regularis , and - 146 - by the diatom, E. peatinalis . Both of these epiphytes were very abundant. A limited number of other species were present including: Cosmarium pyramidatum , Helicodiatyon planatoniaum , E. zygodon , and Neidium ladogense . E. peatinalis was also the dominant epiphyte on W. submersa at station 2 (6-inch depth) with Aphanooapsa deliaatissima as a sub-dominant. The other epiphytes included: Closterium intermedium , Cl. naviaula , Spondylosium pulchetlum vslIC . bambusinoides , Staurastrum paradoxum , C. regnetlii , Oedogonium sp. , Protoderma viride , Scendesmus dimorphus , and E. zygodon. The desmid, Spondylosium pulohellum ■vbli:. bambusinoides , was present only in the collections made on April 30, 1971. The floating W. submersa at station 2 had presumably drifted into the area from other parts of the lake. On these plants the epiphytic community was not the same as that on the W. submersa rooted at a depth of 6 inches. G. vesiculosa was the dominant species present. Sub- dominants (frequency "common") were: Mougeotia spp. , Phormidium tenue , Closterium naviaula , E. vanheurakia var. intermedia , and E. peatinalis . Other species with rare to infrequent occurrences included: Cosmarium bireme , C. regnellii , Spondylosium pulahellum var. bambusinoides , Mierasterias fimbriata , Staurastrum paradoxum, Oedogonium - 147 sp. , Coleoohaete irregularis , F. rhomboides , Nitsahia palea, and Peridinium limbatum (planktonic) . E. peatinalis (diatom) and Closterium navicula (desmid) were the dominant species on W. submersa collected from a depth of 9 inches between stations 1 and 2. A number of desmids other than Cl. naviaula were also present. These included: Cosmarium bireme , C. regnetlii , C. blyttii , C. pyramidatum , C. amoenum , Closterium intermedium , Arthrodesmus incus, and Spondylosium pulahellum var. bambusinoides . Epiphytes, other than desmids, were Oedogonium sp. , Mougeotia sp. , Saendesmus dimorphus , Stephanoporos regularis , F. rhomboides , E. peatinalis , E. vanheurckia var. intermedia , E. aurvata , Dinobryon euryostoma , Osoillatoria tenius , and Aphanoaapsa de lioatissima . W. submersa was collected from a depth of 6 inches at a second intermediate point between stations 1 and 2. As on most samples of this macrophyte gathered on April 30, 1971, E. peatinalis was abundant. Co-dominant with E. peatinalis were two other species, Protoderma viride , and A. delioatissima. Other epiphytes were: Staurastrum paradoxum , Cosmarium pyramidatum, C. bireme, C. blyttii , Closterium naviaula, and Spondylosium pulahellum var. bambusinoides . - 148 - On July 31, 1971, W. submersa , gathered from a depth of 12 inches at station 1, was densely populated by epiphytes. Both Mougeotia spp. and Anabaena osaillavioides were very abundant. Micvospora pachyderma was common. Other species with densities ranging from rare to infre- quent were: Spirogyra sp. , Bulboahaete sp. , Aphanochaete repens , Staurastrum paradoxum , G. vesiculosa , Closterium intermedium , Ct. setaaeum , Dinobryon bavarioum , E. peatinalis , Osoillatoria tenius , and H. fontinatis . For 5 weeks, from August 6 to September 3, 1971, 6-inch slides were exposed at station 2. At the time of collection approximately 50% of the slide area was covered by a fresh-water sponge, Spongilla sp. The remaining areas of the slides were thickly populated by attached algae, especially blue-greens. Several Cyanophy- cean species appeared for the first time in collections on September 3, 1971. The blue-green, Anabaena osaillarioides , was one of the dominants on slides. Filaments of this alga were attached directly to the substrate. Such a manner of attachment in this species contrasts sharply with that observed at other times during the period of study when A. osoillatarioides was part of the raetaplankton. Other blue-greens present included aseriate packets of an - 149 - unknown member of the Nostocaceae, Anabaena lapponiaa, A. variabilis , Aphanocapsa delioatissima , Lynbya nordgaardhii , 0. tenius , and H. fontinalis. The small diatom, Naviaula minima, was very abundant on slides during September, 1971. This alga showed a distinctly clumped distribution, covering some areas of a slide while being absent from other portions. Other attached diatoms were Neidium ladogense , Nitsahia palea, E. pectinalis , and F. rhomboides . Attached members of the Chrysophyceae were Dinobryon bavariaum and D. aalci forme . The most abundant Chlorophyte present was the loosely associated desmid, Staurastrum leptoaladum . Other Chlorophytes included S. pavadoxum , Euastrum binale , Cosmarium regnellii , C. biveme , Closterium navicula , Protoderma viride , Coleoahaete irregularis , Charaaium ambigium , Sahoederia setigera, Mougeotia sp. , Oedogonium sp. , and Spirogyra sp. A Xanthophyte, Stephanoporos regularis , which sometimes appeared in the attached flora of Lake Mize, was also present on slides during September, 1971. Planktonio Algae , September 2^ 1971 On September 3, 1971, a bloom of the green alga, Heliaodiotyon planotonioum , occurred in some areas of - 150 - the lake. This alga occasionally appeared in the plankton. At times it was also trapped by the periphyton, although it did not appear on slides during September, 1971. Elk Lake Studies The attached algae of Elk Lake, Minnesota, were studied during a 6 -week period in the summer of 1967, from July 1 to August 4. Results differed from the July to August studies at Lake Mize, Florida, and are presented here for comparative purposes. Twenty-five species of algae were identified during the study period. Several other species present could not be identified, due, in some cases, to a lack of reproductive structures. Of the 34 species present, 19 were diatoms, 7 were Cyanophytes, and 8 were Chlorophytes. Generally, diatoms dominated the attached flora in both the limnetic and littoral areas, although a few Chloro- phytes and Cyanophytes were sometimes abundant. This domination by diatoms was in striking contrast to Lake Mize, where desmids and other Chlorophytes generally dominated the attached flora. The majority of the species present in Lake Mize were also Chlorophytes. Collections of slides were made from littoral and limnetic stations on July 28 after one week's exposure, on - 151 - August 4 after 2 weeks' exposure, and on August 14 after 3-1/2 weeks' exposure. Collections were also made of some slides in the limnetic area on August 14 after 6 weeks' exposure and of Sairpus sheaths from the littoral area. As in the Lake Mize limnetic studies , colonization patterns that appeared on slides were studied from a comparative view with regard to: {l)time — ^the succession of attached forms that appeared from week to week at a given depth in the lake; (2) spaae — differences in the types of attached algae that appeared on slides in the different vertical layers of the lake. Dominance on slides was determined by counts and estimates. One slide from each level per week was examined. Vertiaal Patterns of Attached Algae and Other Periphyton on Glass Slides in Elk Lake, July to August, 1967 On each of the three collections dates, the greatest number of organisms attached to slides suspended at depths of 1 and 3 meters. Organism frequency was also high on slides suspended at the depth of 2 meters. A substantial reduction in organism frequency occurred on slides submerged at a depth of 4 meters. Below the depth of 4 meters, organism frequency was low on slides. At these lower levels, most attaching algae occurred on that protected portion of the slides near the wooden rack. - 152 - Fourteen diatom species, 1 Chlorophyte species, and 1 Cyanophyte species appeared on limnetic area slides on July 28. Several attaching diatoms had high frequencies on slides collected on July 28, 1967, after 1 week's exposure. Colonization patterns were similar on slides submerged at each of the upper 4 levels. The diatoms, Aahnanthes minutissima and Cocaoneis plaoentula , were the most abundant species present. Other diatoms which were somewhat numerous included: Synedra radians , Epithemia zebra, Epithemia turgida , Gomphonema tanaeolata , and Cymbella affinis. At meter 4, the blue-green, Oscillatoria quadripunatulatai ^as also an important component of the algal flora. Slides collected on July 28, 1967, below the depth of 4 meters had a sparse algal flora. The algae present in limited numbers at these lower levels were chiefly Tabellaria flocculosa , A. minutissima, a.nd C. placentula. The algal flora of slides collected on August 4, 1967, after 2 weeks' exposure, was dominated by the diatom, A. minutissima at the upper 3-meter levels. Large numbers of this small diatom were present, attached broadside to the slides. Sixteen diatom species, 2 Chlorophyte species, 5 Cyanophyte species, and 1 species of Euglena were present on slides in the limnetic area. - 153 - On slides at the 1-meter level, A. minutissima made up 90% of the attached flora. At meter 2, dominance was shared by A. minutissima and G. lanaeblatum. At a depth of 3 meters, A. minutissima and 0. quadripunctulata were the most abundant algae. At a depth of 4 meters, the diatom, C. placentula , and the green algae, Mougeotia sp. , Oocystis sp. , and Radiococcus nimbatus , were the most important components of the algal flora. A. minutissima , abundant at the upper levels, was present only in limited numbers. Below meter 4, algal frequency was low with Tabellaria floaculosa and Cyolotella bodin present in low frequencies. The communities of attached algae present on slides at the 3-meter depth in the limnetic area of Elk Lake on August 14, 1967, after 3 weeks' exposure, showed more variation than on earlier dates (Tables 35, 36, and 37). At the upper two levels, species diversity was comparatively low and A. minutissima continued to be a dominant, making up 51% of the attached flora on slides at meter 1 and 86% at meter 2. 0. quadripunatulata was also abundant on slides at the 1-meter level. Both of these algae attached broadside to the slides, adhering closely to the substrate. - 154 - TABLE 35 Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 1 Week, July 21 to July 28, 1967 Numb^ er of Spec ies 1-Meter depth 2-Meter depth 3-Meter depth 4-Meter depth 6-Meter depth Chlorophytes 1 ab. ab. ab. ab. Chrysophytes 9 11 13 11 8 Cyanophytes ab. 1 ab. 2 ab. Total Number of Species 10 12 13 13 8 Note: ab. = absent - 155 - TABLE 36 Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 2 Weeks, July 21 to July 28, 1967 Numb^ er of Species 1-Meter 2-Meter 3-Meter 4-Meter 6-Meter depth depth depth depth depth Chlorophytes ab. ab. ab. 2 1 Chrysophytes 13 11 11 9 6 Cyanophytes 1 ab. 5 1 ab. Euglenophytes ab. ab. ab. 1 ab. Total Number of Species 14 11 16 13 7 Note; ab. = absent - 156 - TABLE 37 Number of Algal Species Present at Various Depths on Glass Slides Suspended in the Limnetic Area of Elk Lake, Minnesota, for 3-1/2 Weeks, July 21 to August 14, 1967 Numb er of Spe :;ies 1-Meter depth 2-Meter depth 3-Meter depth 4-Meter depth 6 -Meter depth Chlorophytes ab. ab. 2 2 1 Chrysophytes 10 8 14 8 2 Cyanophytes 3 ab. 5 2 ab. Euglenophytes ab. ab. 1 1 ab. Total Number of Species 13 8 22 13 3 Note: ab. = absent ma - 157 - Two protozoans, Vorticella and Actinophyrs, \fere numerous on slides at the upper two levels. Slides submerged at a depth of 3 meters were covered by a thick film of brown debris. Dominance was shared by four algal species. Two of these, A. minutissi and 0. quadripunctulata , were forms which attached directly to the substrate. Two others, Gomphosphaeria laaustvis and Synedra radians, were associated with the debris and did not adhere closely to the slides. Species diversity was also higher on slides at meter 3 than at other levels (see Table 37). The attached protozoan, Vortiaella , was the chief grazer present. Slides at the 4-meter level did not have the thick film of debris which had been present on slides at meter 3. A. minutissima and S. radians were the most abundant algae on slides. The protozoans, Vorticella and Aatinophyrs , vjere abundant on slides at the 4-raeter level. Again, slides suspended at levels below 4 meters were only sparsely populated by algae and other attached forms. Slides were also collected from the 3-meter level on August 14, 1967, after 6 weeks' exposure. These slides were covered by a thick coat of debris. The dominant - 158 - algae were forms which tended to drift in the debris rather than attach firmly to the substrate. Gomphosphaeria lacustris made up 46%, Rhopalodia gibba made up 30%, and Cymbella affinis made up 18% of the algae associated with meter 3 slides after 6 weeks' exposure. At this time, the blue-green, G. lacustris , and one of the diatoms^ R. gibba, were also present in the plankton (Baker, 1967). Both were also found on the sediments and as epiphytes on Soirpus in the littoral area. Variation with Time in the Algal Flora Present on Glass Slides, Elk Lake Limnetic Area, August , 1967 Resupinate forms were the pioneers in colonizing glass slides at the upper 4 levels. The diatoms, A. minutissima and C. plaoentula, were prominent on slides after 1 week's exposure. Both of these species were examples of the resupinate type. Prostrate forms continued to be abundant on slides after 2 weeks' exposure during August, 1967. At 3 of the 4 upper levels, ^4. minutissima continued to be abundant. A closely adhering blue-green, 0. quadripunctulata , became abundant also on slides at a depth of 3 meters. And, the colonial greens, Radiococcus nimbatus and Oocystis sp., became abundant on slides at the 4-meter level. Both of these colonial algae were embedded in mucilage which also adhered to the substrate. - 159 - On slides at each of the upper 3- meter levels, Gomphonema lanoeolatum became abundant. This alga represented a second attaching form to become abundant on slides in Elk Lake. Cells of G. lanoeolatum attached vertically to the substrate via a button of mucilage on one end of the cell. The green filamentous species, Mougeotia sp. , also became abundant on slides at a depth of 4 meters. This species attached vertically to the substrate as did G. lanoeolatum. Attachment for Mougeotia sp. was by means of a holdfast. After 3 weeks' exposure, resupinate forms remained dominant on slides at meter levels 1 and 2. At meter 3, a thick film of debris had formed. Two of the prostrate species remained abundant. However, 2 other abundant species, Gomphosphaeria laoustvis and Synedra radians, were forms associated with the debris on slides. S. radians was also the most abundant species at meter 4. Slides exposed for 6 weeks at meter 3 carried the successional tendency further. Three species, G. laoustris , Rhopalodia gibba, and Cymbella af finis, ^ere abundant. All 3 were species which loosely associated with the substrate, tending to float in debris rather than attach directly to the slide. Round (1964) in commenting upon the communities of attached algae which make up successional stages on glass - 160 - slides, states that slides primarily attract a mixture of species from epiphytic and epilithic habitats. After this initial colonization, he observed that slides secondarily trap species from the epipelic and planktonic habitats. Slides exposed at the depth of 3 meters in Elk Lake during August, 1967, for 3 or 6 weeks, did secondarily trap planktonic species. This trapping occurred after the accumulation of debris on the slides. Attached Algae of the Littoral Zone, Elk Lake ^ August, 1967 Colonization of slides placed at depths of 5 meters and 1 meter in the littoral area of Elk Lake was similar to the colonization of slides placed in the limnetic area at the upper 2-meter levels. Aohnanthes minutissima was a dominant on slides at each weekly collection period. Other major species, Cooooneis placentula , Gomphonema lanaeolatum , Cymbella af finis , Synedra radians, and Epithemia zebra, were also found on limnetic area slides. The differences which did exist between littoral area slides and upper level limnetic slides included the appearance of a prostrate green alga, Coleoahaete orbioularis . Grazers were also more diverse on slides in in the littoral zone. Aatinophrys appeared on slides during the first week with hypotrichs , attaching rotifers, ciliates, and gastrotrichs appearing the second week. - 161 - Gastrotrichs and rotifers were also present during the third week, moving easily about in the debris attached to slides. Except for the hypotrichs, which fed on Achnanthes minutissima , the feeding habits of these invertebrates were not observed. The epiphytic algae of the aquatic macrophyte , Scirpus sp. , in the littoral area of Elk Lake were also examined. Epiphytes which were present on both Scirpus and on glass slides included E. zebra, E. turgida, Ehopalodia gibba, Amplipleura pellucida , Cymbella af finis , Nitschia palea , Amphora ovalis , Gomphosphaeria laaustris , and Radiooooous nimbatus . The chief epiphyte, not present on glass slides, which was present in large quantities on Scirpus was a species of Oedogonium. Achnanthes minutissima , Cocconeis placentula , and Oscillatoria quadripunctulata were not detected on Scirpus. However, this was probably due to the difficulty of obtaining the closely adhering forms in scrappings from Scirpus , not to their absence. Comparison: Attached Algae of Lake Mize, Florida, and Elk Lake, Minnesota Few of the species of attached algae found in the dystrophic Lake Mize, Florida, and the mesotrophic. Elk Lake, Minnesota, were the same. Two diatoms, Nitschia palea and Gomphonema lanceolatum , and 1 Chlorophyte, - 162 - Tvotoderma viride , were the only species common to both lakes. The chemical differences in Lake Mize and Elk Lake were reflected in an almost completely different alga flora in the two lakes. Some of the floristic differences in the two lakes may be elaborated on as follows: 1. A large number of desmids were present in Lake Mize whereas only single specimens of a few species were found in Elk Lake. 2. Diatoms formed the majority of the attached flora in Elk Lake while diatoms were generally subdominant to Chlorophytes in Lake Mize. 3. The most common diatoms in Lake Mize were several species of the genus, Eunotia. In contrast, Aahnanthes minutissima was the most frequently appearing diatom in the flora of Elk Lake. General similarities between the attached flora of the two lakes should also be cited. Closely adhering filamentous Cyanophytes appeared on the slides of both lakes during the month of August, although the species were different. In Elk Lake, Oscillatovia quadripunatulata was sometimes abundant on limnetic area slides, while the closely adhering Phormidium tenue was abundant in Lake Mize during August, 1969. Large, prostrate Chlorophytes appeared on littoral area slides in both lakes. In Elk Lake, Coleoohaete orbioularis was common on slides while Protoderma viride and Coleoohaete irregularis were frequently common to abundant on littoral area slides in - 163 - both lakes. Prostrate greens were also absent or rare on limnetic area slides in both Elk Lake and Lake Mize. In both lakes, closely adhering, resupinate forms made up many of the pioneering species which attached to recently submerged substrates. In Lake Mize, filamentous species were also sometimes included among the first attachers to a bare substrate. These were rare on Elk Lake slides except at the depth of 4 meters. Conversely, few stalked diatoms appeared in Lake Mize while such forms were common on Elk Lake slides. In Elk Lake, a large film of debris collected on slides submerged at the depth of 3 meters after 3 weeks. A number of metaplanktonic and planktonic species became associated with this debris, becoming more abundant than the closely adhering and stalked diatoms. The layer of debris on 6- to 30-inch slides in Lake Mize never became as thick as that in Elk Lake. (Because most of the light was absorbed by upper layers of the lake, slides submerged at 3 meters in Lake Mize had a very sparse flora.) Fewer metaplanktonic species were also associated with Lake Mize slides in the latter stages of succession than on the 3-meter Elk Lake slides. VI. DISCUSSION As could be anticipated, the species composition and relative frequencies of organisms within the communi- ties of attached algae in Lake Mize were dependent upon a number of factors. Losses Due to Peeling Losses due to peeling from an established periphyton community had a major influence upon the species diversity and the relative abundance of species within the community. Peeling — the detachment of portions of the periphyton from a substrate — may be caused by current, by decomposition gases (Neal, Patten, and DePoe , 1967), or by movements of fish and other animals. Examination of periphyton dislodged from the substrate by slight movements in the water and of species falling to the bottom of collecting jars indicated that losses of individual species were not in proportion to the relative frequencies of the species within the part of the community left adhering to the substrate. Slightly greater losses of the loosely associated species of the meta- plankton occurred than of tightly appressed species. Most of these metaplanktonic species in Lake Mize were desmids - 16 4 - - 165 - which were frequently rare species in the periphyton. Two blue-greens, Osaillatoria tenuis and Anahaena oscil- lavioides, at times were also part of the loosely associated metaplankton. At such times, losses by peeling were accom- panied by substantial decreases in frequencies of these two algae. Peeling was responsible for the frequency decrease in 0. tenuis on glass slides between August 20 and September 11, 1969. Peeling due to decomposition gases within the debris or to currents was of rather irregular occurrence on a given substrate with respect to time. Nor did peeling take place at the same rate on replicate substrates subjected to the same limnological conditions. This peeling and subsequent recolonization by tightly adhering forms on portions of the substrate undergoing peeling sometimes caused a great deal of variation between closely situated periphyton communities on replicate substrates. Such variation, however, was not nearly as large as that encountered in different seasons, at different localities in the lake, on different substrates at a particular time, or at different depths. Changes with Time: Colonization and Succession Although metaplanktonic species have a slightly higher rate of loss from the periphyton than tightly adhering forms , the members of a given attached species of 166 - any form in the open waters of the lake may be presumed to be a function of the relative abundance of the species within the periphyton and of the turbulence in the lake at that time. Such species when present in plankton samples are generally referred to as tychoplankters. Colonization of a clean substrate introduced into the lake was initiated within hours by drifting tycho- plankters. Most pioneer attaching species were not the same at different seasons or during the same year. Instead, pioneer attachers on a bare substrate were generally those species which were the most abundant in the lake (or area of the lake) at the time that the substrate was submerged. After attachment to a substrate by an individual cell or other unit of dispersal, subsequent cell divisions occurred if environmental conditions were suitable. A scattering of single-celled forms then developed from the original point of attachment while filament or colony formation took place for those forms. Microscopic examination of slides exposed for 7 days in the upper 6 to 18 inches of the lake generally showed considerable variation in the frequencies of attached species which were capable of rapid divisions, e.g., diatoms, Chance apparently dictated the numbers of such tychoplank- ters which made contact with a clean substrate during the first days after submergence. Subsequent rapid divisions on a substrate to which many tychoplankters chanced to - 167 - attach resulted in higher frequencies of the species than on replicate substrates where fewer tychoplankters made contact. Pioneering attaching species in Lake Mize were generally either tightly adhering, resupinate forms or filamentous and secured to the substrate by a holdfast. With the passing of time (up to 3 to 5 weeks generally) debris collected on the substrate. This accumulation of debris was accompanied by an increase in the number and frequency of metaplankters present. Metaplanktonic forms also occurred intermingled with filamentous forms, apparently requiring an association with either debris or filaments if they were to be retained on a substrate subjected to light currents. This retention of the metaplankton was by no means absolute. After a period of time, generally exceeding 3 to 5 weeks, the layer of debris accumulated was usually great enough so that peeling ensued with a loss of many members of the periphyton. Secondary succession then proceeded to take place on cleared areas of the substrate. Influence of the Substrate Authorities are of divergent opinions regarding the degree and nature of the selectivity exerted by - 168 - different types of substrates for various attached species (Godward, 1937; Castenholz, 1957; Sladeckova, 1962). In Lake Mize no absolute substrate specificity by any species of attached algae could be observed. However, the epiphytic communities on various macrophyte species at the same depth in the same area of the lake were usually significantly different. These differences existed with both naturally growing plants and those submerged for identical submergence periods in plastic or glass enclosures. The macrophytes involved were apparently exposed to the same environmental conditions so that substrate differences would appear to be the cause of variation in the epiphytic communities. However, if the same macrophytic species was collected at the same littoral station over a period of several years, the epiphytic species which were prevalent on it in time disappeared or sometimes appeared on another vascular aquatic species at the same or different littoral stations. It follows logically that the influence of the substrate is part of a complex interaction of factors acting upon the epiphytic communities. A few references exist in the literature to this interaction of the substrate and other environmental conditions. After reviewing several papers by Pearsall (1917, 1920, 1921, 1933) on rooted - 169 - vegetation and the distribution of animals in English lakes, Macan (1970) concluded that on any one type of substrate, conditions for attachment by algae are different in different areas of a lake. Current and its interaction with different types of substrates seem to be of critical importance in Lake Mize. During August, 1970, the filamentous sedge, Webstevia submevsa , was placed in the limnetic area of the lake, a part of the lake which is subject to currents. A stratified community of epiphytes with many meta- planktonic species soon developed. Limnetic area glass slides, however, had few metaplanktonic species and lower overall frequencies of all attached species. In littoral areas of the lake, the filamentous macrophytes, W. suhmersa and Utviaulavia olivacea , were generally more densely populated than the broader leaf blades and leaf sheaths of other macrophytes. The greatest differences existed when epiphytic communities on filamentous macrophytes were compared with the periphyton of glass slides. At least one reference has been made in the literature stating that aquatic macrophytes with finely divided leaves tend to be more heavily populated by many epiphytes, including desmids, than macrophytes without such leaves (Sculthorpe, 1967). It may be hypothesized - 170 - that the morphology of finely divided leaves makes for easier attachment and/or more protection for epiphytes. The filamentous morphology of W. suhmersa and U. oliVaoea appears to do likewise. Glass slides are a convenient means of studying attached algae and are commonly used for such research. Regarding the effectiveness of this method, the point has been made earlier that both population density and the number of species were lower on glass slides than on the aquatic macrophy te , W. suhmersa , in Lake Mize. This was the case both in the open waters of the limnetic area and in protected enclosures in the littoral zone. However, inside protective enclosures, the periphyton communities of glass slides and W. suhmersa more nearly resembled each other quantitatively and qualitatively. On littoral area slides, frequencies of most species of both firm attachers and metaplankters were greater than on limnetic area slides at the same depth. Comparisons between the attached communities on glass slides and on nonf ilamentous macrophytes such as Sphagnum maarophyllum and Mayaaa auhleti showed somewhat comparable frequencies of attached algae. However, macrophytes of any morphological form were more likely to support metaplanktonic forms and certain species of adhering blue-greens than were glass slides. Conversely, other blue-green species were more likely to appear on glass. - 171 - Except for some inetaplanktonic desmids, all species of attached algae which were present in Lake Mize appeared at some time during the study on glass slides. Both Castenholz (1967) and Sladeckova (1962) have commented upon the relative absence of blue-greens recovered from glass slides. In Lake Mize, blue-greens did occur on glass slides, especially in more protected portions of the littoral area. During August, 1970, the blue-greens, Hapalosiphon fontinalis (prostrate, filamentous) and Anabaena osoillarioides (loose, filamentous), were rare and infrequent, respectively, on glass slides submerged 6 inches in the limnetic area. In contrast, these same species were very abundant on W. submersa submerged to a comparable depth in the limnion of the lake. These two blue-greens were also common to abundant on other aquatic macrophytes during August, 1970. While this observation tends to agree with those of Castenholz and Sladeckova, other observations from Lake Mize do not. Under certain conditions, blue-greens had high frequencies on glass slides. Both H. fontinalis and A. osoillarioides were sometimes abundant on slides submerged at station 2. This station was located behind a projecting arm of the shoreline which protected it from - 172 - north-south and south-north currents. During August, 1969, two blue-green species, Osoillatoria tenuis and Phormidium tenue , were also coininon and very abundant, respectively, on limnetic area slides. It seems likely that some blue-greens, e.g., H. fontinalis and A. osoillarioides , are weak attachers, especially as compared to the diatom, Eunotia. Lake Mize is surrounded by trees which act as a wind buffer. This added protection from the wind, which diminishes the magnitude of currents, probably allows weakly adhering blue-greens to attach to glass, although losses of blue- greens from glass were higher than from most macrophytes. In quieter areas of the lake (station 2) , even glass slides had a diverse and abundant blue-green flora. Influence of Physical Factors — Current The influence of the current in Lake Mize has already been alluded to in the discussion of substrates. One additional observation about current should be made. When slides were placed in an area subject to the fastest currents (just above the outflow ditch during a time of high water) , the slides became covered by several species of the diatom, Eunotia, i.e., Eunotia pectinalis , E. vanheurckia, and E. zygodon with few other algae present (Table 33) . - 173 - In Lake Mize, therefore, only firmly attaching, resupinate forms were able to remain attached to slides in relatively fast currents, and, 95-98% of these were diatoms. Due to the absence of filamentous and metaplanktonic species, diversity was low. Unlike Lake Mize, Elk Lake, Minnesota, was only partially surrounded by trees and as such was more exposed to wind. In Elk Lake, when slides were submerged at meter intervals in the top 4 meters of the lake, most of the attached species found in the upper 2 meters were tightly adhering, resupinate forms, e.g., Achnanthes minutissima . Surface currents presumably did not penetrate to the depth of 3 meters where slides supported a number of planktonic and metaplanktonic species. Influence of Physical Factors — Light Light was a severely limiting factor for attached algae in Lake Mize due to the darkly colored waters. Only in the upper 6 to 30 inches of the lake was light not reduced to a critically low level. The degree of huraolimnic acid coloration of the water fluctuated from time to time, so that the vertical range of the producers varied somewhat as a function of the amount of coloration. The vertical range of producers also varied with different - 174 - substrates, extending deeper on Websteria submersa than on glass slides. The depth of maximum algal frequencies was also different on these 2 substrates, generally occurring at 6 inches for glass and at 18 inches for W. submersa. An interaction of several factors probably accounted for these differences. Losses due to peeling from both plants and slides were probably greatest at 6 inches due to surface currents in the lake. At all depths, losses were presumably greater from slides than from W. submersa. Only near the surface of the lake was photosynthesis sufficient to maintain a rapidly increasing algal density while also replacing losses from slides. With fewer losses on W. submersa at 18 and 30 inches than at 6 inches, greater population growth occurred despite the decreased photosynthesis. In the green-colored waters of Elk Lake, light became limiting for the attached flora of slides only below a depth of 3 meters. Influence of Physical Factors — Temperature An increase in temperature in Lake Mize during late summer and early fall was accompanied by an increase in the frequency of Cyanophytes among the attached flora during the 3 years of the study period. In late July or early August, 2 Cyanophyte species generally became - 175 - abundant to very abundant on some substrates in the lake. These species were not always the same from year to year. In 1969, high frequencies were recorded for Oscillatoria tenuis and Phormidium tenue while Anabaena osaillarioides and Hapalosiphon fontinatis became abundant in both 1970 and 1971 during the warmer months. Seasonal Influences The seasonal variation in the periphyton of Lake Mize was not as great as that reported for lakes in the state of Washington (Castenholz, 1967) or for plankton (Fogg, 1966), Other than the influence of high temperatures associated with summer and fall, the effect of wind and storms seemed to be the chief seasonally related factor influencing the diversity and abundance of the attached algae. Slides placed in the limnetic area of the lake during the comparatively calm 1968-19 69 winter season had a flora characterized by a number of species of metaplanktonic desmids and by high frequencies (abundant) of filamentous greens. Slides placed in the limnetic area during the periods August to September, 1969, and July to August, 197 0, when the lake's waters were occasionally turbulent from the action of summer storms, had a flora dominated by tightly adhering, resupinate forms. Few filamentous or metaplanktonic forms were present. - 176 - An exception was Osoillatoria tenuis which in August, 1969, was common on limnetic area slides. Large losses from slides of this alga occurred between August 20 and September 11. In July, 1970, similar losses from slides of the metaplanktonic Gleooystis vesioulosa also occurred. At these times, summer thunderstorms were common and probably accounted for the large losses of algae from slides. Conversely, many filamentous and metaplanktonic forms were abundant in some areas of the littoral zone during the summer and fall months where waters were presumably calmer and the area more protected. There the periphyton persisted through turbulent periods caused by rains and wind. This relatively restricted occurrence and frequent losses of filamentous and metaplanktonic forms during the summer and fall seasons may be contrasted with the winter season when such forms were widespread in all parts of the lake. Losses during December, January, and February (1968-1969) were also minimal. A number of algal species were sporadically abundant in the periphyton of Lake Mize. Except for warmer summer and fall months, one or more Chlorophytes were dominant components of the periphyton. However, the pulses of individual species could not be predicted as to - 177 - month or season. The occurrence of particular species in the periphyton during the December, 1968, to September, 1971, was noncyclic. VII. SUMMARY A floristic survey from December, 1968, to September, 1971, provided a record of the communities of attached algae in Lake Mize, Florida. Eighty-nine algal species were identified and monitored during the study period. Thirteen other unidentified species were also present. Of the 102 species distinguished, 63 were Chlorophytes, 2 were Euglenophytes, 22 were Chrysophytes , 2 were Pyrrophytes, 11 were Cyanophytes, 1 was a Xantho- phyte, and 1 was a Chloromonadophyte. Both quantitatively and qualitatively, desmids and filamentous Chlorophytes were usually an important part of the periphyton in Lake Mize. Several acidiophilic diatoms were abundant at certain times while Cyanophytes generally reached high frequencies only during the July to September period. Counts and estimates were used to determine the relative abundance and frequencies of the species present under different environmental conditions. Such analyses indicated that at any given time, and place, a number of factors influenced the composition of the periphyton. The most important conclusions drawn from this study regarding the influence of certain seasonal and environ- mental factors upon the phyco-periphyton are: - 178 - - 179 - Algae employing particular modes of attachment were more abundant under some conditions than in others. Generally, tightly adhering, resupinate forms attained higher densities on glass slides than filamentous and loosely associated metaplanktonic species. Conversely, the epiphytic flora of the filamentous sedge, Websteria submersa, contained a large number of both strong and weak attachers. Substrates of any type exposed to a moderate current were populated almost exclusively by tightly adhering, resupinate forms. At any given time, different areas of the lake supported somewhat different periphyton communities. In calmer areas of the lake or in protected enclosures, metaplanktonic and filamentous species were more abundant on all substrates than in areas subjected to currents and turbulence. Light was an important environmental factor in determining the taxonomic composition of the periphyton community, Chlorophytes were generally abundant only in the upper 6 to 18 inches of the lake. Attached Chrysophytes had a broader vertical range, frequently remaining common to a depth of 30 inches on glass and 42 inches on Websteria submersa. Light requirements for Cyanophytes were variable with some species restricted to the upper 6 to 18 inches of the lake and other remaining common to a depth of 42 inches . Seasonal influences upon the attached algae of Lake Mize were not as pronounced as those reported for northern lakes. During the study period pulses of individual species occurred in the periphyton but their occurrence could not be predicted as to month or season. Desmids and filamentous Chlorophytes were generally abundant throughout the year while maximum frequencies of Cyanophytes occurred during the warmer summer and fall months. The lack of turbulence from winds and storms during the winter season also influenced the periphyton, permitting metaplanktonic and filamentous species to become widespread in the lake. - 180 - When clean substrates (slides or plants) were submerged in the lake, the pioneering attachers were usually the most abundant resupinate and/ or filamentous forms in the lake at the time. With time, frequencies of the early attachers increased. Under proper conditions, species diversity also increased as metaplanktonic forms became associated with the substrate. Peeling and a loss of metaplanktonic and other attached species generally occurred with exposure periods exceeding 3 to 5 weeks or under conditions of sudden turbulence, e.g., storms. The attached flora of the dystrophic Lake Mize, Florida, was very unlike that of the mesotrophic Elk Lake, Minnesota. Whereas Chlorophytes were the most important component of the periphyton in Lake Mize, diatoms formed the majority of the attached flora in Elk Lake. APPENDIX - 182 - TABLE 38 Master List of the Attached Algae of Lake Mize, Florida, and Planktonic Species Associated with Communities of Attached Algae, December, 1968, to September, 1971 Chlorophyta Volvocales Eudorina elegans Ehrenberg* Tetrasporales Gleoaystis vesiculosa Naegeli Ulotrichales MioTospora tumidula Hazen Miorospora pachyderma (Wille) Lagerheim Protoderma viride Kutzing Aphanoohaete repens A. Braun Helioodiatyon planatonioum (Whit.) Whitford & Schumacher* Coleochaete irregularis Pringsheim. Diaranoohaete reniformis Hieronymus Oedogoniales Oedogonium reinschii Roy Oedogonium spp. Bulboohaete spp. Chlorococcales Charaoium amhiouum Hermann. Schoederia setigera (Schroed.) Lemmermann Coelastrum sphaerioum Nageli Ankistrodesmus falcatus (Corda.) Ralfs Soenedesmus dimorphus (Turp. ) Kutzing. Zygnematales Spirogyra spp. Mougeotia spp. Spirotaenia condensata Breb. Netrium digitus (Ehren.) Itzigsohn and Rothe - 183 - TABLE 38 — Continued Closterium incurvum Brebisson Closterium intermedium Ralfs Closterium libellula Focks Closterium navicula (Breb.) Lutkem. Closterium setaceum Ehrenberg Pleurotaenium minutum (Ralfs) Delponte Pleurotaenium subcoronulatum var . detum (Turner) West & West Triploaeras gracile Bailey Tetmemorus brebissonii (Menegh. ) Ralfs Euastrum affine Ralfs Euastrum binale (Turp. ) Ehrenberg Euastrum ciastonii Racib. Micrasterias fimbriata Ralfs Aatinotaenium cruoiferum (De Bary) Telling Cosmarium amoenum Ralfs Cosmarium bireme Nordstedt Cosmarium blytii Wille Cosmarium ornatum Ralfs Cosmarium pygaeum Archer Cosmarium pyramidatum Brebisson Cosmarium regnellii var. pseudoregnellii (Messikommer) Krieger & Gerloff Arthrodesmus incus (Breb.) Hassall Arthrodesmus octoaornis Ehrenberg Xanthidium antilopaeum var. minneapoliense Wolle Xanthidium subhastiferum var. towerii (Cushman) G. M. Smith Staurastrum leotocladum Nordstedt Staurastrum paradoxum Meyen Staurastrum pyramidatum West Staurastrum spp. Onahyonema taeve var. latum West & West Hyalotheaa undulata Nordstedt Hyalotheaa dissiliens (Smith) Brebisson Desmidium baileyi (Ralfs) Norstedt Bambusiana brebissonii Kutzing Spondylosium pulahellum var. bambusinoides (Wittr.) Lundell Euglenophyta Euglena sp. Phaous lemmermannii ($wkr. ) Skvortzow - 184 - TABLE 38 — Continued Xanthophyta Stephanoporos regularis (Pasch.) Bourrelly Chrysophyta Chrysophyceae Dinobryon bavaricum Imhof Binobryon oalci forme (Bachmann) Hilliard & Asmund Dinobryon cylindricum Imhof* Dinobryon euryostoma (Leram. ) Hilliard & Asmund Mallomonas oaudata Conrad* Mallomonas sp* Synura sphagniaola Korsch* Lagynion scherffellii Pascher Ehipidodendron splendidum Stein Bacillariophyceae Asterionella formosa Hassal.* Eunotia ourvata (Kutz.) Lagerheim Eunotia pectinalis (Kutz.) Rabenhorst Eunotia vanheurokia var . intermedia (Kras. ex. Hust. ) Patrick Eunotia zygodon Ehrenberg Frustulia rhomboides var. saxoniaa (Rabh. ) de Toni Neidium ladogense var. dens estriatum (Oestrup) Foged Navicula minima Grunow Gomphonema lanoeotatum Ehrenberg Nitsahia patea (Kutz.) W. Smith Surirella biseriata var. constriata Grunow Surirella robusta var. splendica (Ehr.) Van Heurck. Pinnularia gibba Ehrenberg Pyrrophyta Peridinium limbatum (Stokes) Lemmermann* Peridinium westii Lemmermann* Chloromonadophyta Gonyostomum semen (Ehr.) Diesing.* - 185 - TABLE 38 — Continued Cyanophyta Chroococcales Aphanoaapsa delioatissima West & West Oscillatoriales Osaillatoria tenuis Ag . Phormidium angustissimum West & West & West Phormidium tenue (Meneg.) Gomont Lynhya nordgaardii Wille Anabaena osoillavioides Bory Anabaena variabilis Kuetzing Anabaena lapponica Borge Anabaena flos- aquae (Lyngh.) Brebisson* Hapalosiphon fontinalis (Ag.) Bornet. Calothrix epiphytiaa West & West *Planktonic species. Figure 17. Germlings of Bulhoahaete sp. on Wehsteria submevsa (x400) , Lake Mize. Figure 18. Colony of Protoderma viride , a prostrate Chlorophyte , with diatoms, Nitsahia palea and F.rustulia rhomboides (xl,400). Lake Mize. Figure 19. Osoillatovia tenuis filaments (xl,300), Lake Mize. Figure 20. Anabaena osoillavioides (xl,000), Lake Mize. - 187 - Figure 21. Closterium setaceum (x320) , Lake Mize. Figure 22. Closterium naviaula (x600) , Lake Mize. Figure 23. Oedogonium sp. , showing holdfast (x400) , Lake Mize. Figure 24. Branched filaments of Hapalosiphon fontinalis (x500) , Lake Mize. - 189 - Figure 21 Figure 22 ■ ir^r o^H^^^fH^^^H w v.. ^Jj^ K Jft. '^ ^J^? E m . .T-^^ ^ I^K_*!iA. . • >r- • |. ^W -vT[ M) J| -^ ■vJ 1 /yi'- •^ J 1 fl 1 ^^M^^^^BKB 1-1 Figure 23 Figure 24 Figure 25. Portion of the attached coimnunity of a glass slide, showing Cosmarium vegnellii Eunotia sp. , and a filamentous Oomycete (x600) , Lake Mize. Figure 26. Frustulia rhomhoides var. saxonica (x750) , Lake Mize. Figure 27. Rhipidodendron splendidum , a heterotrophic Chrysophyte (x300) , Lake Mize. Figure 28. Epithemia zebra {x400) , Elk Lake. - 191 - Figure 26 Figure 27 Figure 28 - 192 - TABLE 39 Master List of the Attached Algae and Planktonic Species Associated with Attached Algae in Elk Lake, Minnesota, August, 1967 Chlorophyta Ulotrichales Protoderma viride Kutzing Coleoohaete orbicularis Pringsheim Chlorococcales RadiocoGcus nimbatus (de Wild.) Schmidle Ooaystis sp. Oedogoniales Oedogonium sp. Bulbochaete sp. Zygnematales Mougeotia sp. Spirogyra sp. Euglenophyta Euglena sp. Chrysophyta Bacillariophyceae Cyctotella bodin var. affinis 0. Mull. Tabellaria flocculosa (Roth.) Kutzing. Synedra radians Kutzing. Synedra ulna (Nitz.) Ehrenberg Synedra aatinastroides Lemmerman Achnanthes minutissima Kutzing CooQoneis placentula Ehrenberg Amplipleura pelluoida Kutzing Gomphonema lanoeolatum Ehrenberg Gomphonema acuminatum var. coronata (ehr.) W. Smith - 193 - TABLE 39 — Continued Gomphonema intriaatum var. pumila Grun. Amphora ovalis Kutzing. Cymhella affinis Kutzing Cymhella cistula (Hemprich) Grun. Epithemia turgida (Ehr. ) Kutzing Epithemia zebra (Ehr.) Kutzing Rhopalodia gibbia (Ehr.) 0. Muller* Nitsahia palea (Kutz.) W. Smith Nitschia gracilis Hantzsch. Cyanophyta Chroococcales Merismopedia sp. Coelosphaerium sp. Gomphospaeria aponina Kutzing Gomphospaeria laaustris Chordat* Osc ilia tor iales Osaillatoria quadripunatulata Bruhl & Biswas Lyngbya sp. Spirutina sp. *Planktonic species. - 194 - TABLE 4 0 The Algal Flora Present on Vertically Positioned Glass Slides Suspended in the Limnetic Zone of Lake Mize during January, 1969; August, 19 69; and August, 19 70 (VA = Very abundant, A = Abundant , C = Common , I = Infrequent, R = Rare) January August August 1969 1969 1970 Chlorophyta Protoderma viride Kutzing Coleoahaete irregularis Pringsheim Ankistrodesmus fatcatus (Corda.) Ralfs Heticodiotyon ptanatonicum Oedogonium spp. Bulboohaete sp. Spirogyra spp. Mougeotia spp. Closterium setaaeum Ehrenberg Closterium intermedium Ralfs Closterium navicula (Breb. ) Lutkem. Pteurotaenium subcoronu- latum var. detum (Turner) W. & G. S. West Triploaerus graoile Bailey Euastrum affine Ralfs R R R R R R I R I I R R R R A R R P R R R R R - 195 - TABLE 40 — Continued January August August 1969 1969 1970 Euastrum oiastonii Racib. R Euastrum binale (Turp. ) Ehrenb. Micrasterias fimbriata Ralfs R Cosmarium amoenum Ralfs R Cosmavium ornatum Ralfs R R Cosmarium regnellii var. psuedoregneltii (Messikoinmer) Krieger & Gerloff R I Cosmarium pygmaeum Archer R Cosmarium hireme Nordstedt R A R Cosmarium pyramidatum Breb. Xanthidium antilopaeum var. minneapoliense Wolle R Staurastrum leptoaladum Nordstedt. Staurastrum gladiosum Turner R Staurastrum orbiaulare Ralfs Staurastrum paradoxum Meyen R R Staurastrum sp. 1 R Staurastrum sp. 2 R Arthrodesmus incus (Breb.) Hassall R 196 - TABLE 40 — Continued January August August 1969 1969 1970 Avthvodesmus octocovnis Ehrenberg R Hyalotheaa dissiliens (Smith) Brebisson R Hyalotheaa undutata Nordst. R Desmidium haileyi (Ralfs) Nordstedt. R Chrysophyta Dinobryon calciforme (Bachmann) Hilliard & Asmund I Dinobryon eury stoma (Lemm. ) Hilliard & Asmund R Mallomonas aaudata Conrad R I Rhipidodendron sptendidum Stein I Eunotia curvata (Kutz.) Lagerheim I Eunotia peatinatis (Kutz.) Rabenhorst I A C Eunotia vanheruckia var . intermedia (Krasske ex. Hustedt) Patrick Frustulia rhomboides var. saxonioa (Rabh. ) de Toni I R R Neidium ladogense var. densestriatum (Oestrup) Foged R R - 197 TABLE 40 — Continued January August August 1969 1969 1970 Pyrrophyta Cyanophyta Naviaula minima Grunow. R C Gomphonema lanaeotatum Ehrenberg C Nitssahia palea (Kutz.) W. Smith I C Surirella biseviata var. aonstricta Grunow. R Asterionella formasa va.i:. graaillima (Hantz.) Grunow. R Peridinium limhatum (Stokes) Lemmermann R Peridinium westii Lemmermann R Anacy stis marina Crouet & Daily A Osailtatoria tenuis Ag. A Phormidium angustissimum West & West I Phormidium tenue (Menegh.) Gomont I VA Phormidium tenue (Meneg.) Gomont R R Anabaena Osoillarioides Boay R I Hapalosiphon fontinalis (Ag. ) Hornet. R Calothrix epiphytiaa West & West R - 198 - TABLE 40- '^ontinued January 1969 August 1969 August 1970 Euglenophyta Euglena sp. Total Number of Species VA 40 27 15 Note: Frequencies given here represent the maximum population occurring on glass slides placed in the limnetic zone of Lake Mize. This maximum frequency may have occurred on slides at any of the following levels: 6 inches, 18 inches, 30 inches, or 42 inches. Depending upon the species, cells, filaments, or colonies may have been counted. Very Abundant (VA) represents a frequency of over 5,000 per square centimeter. Abundant (A) represents a frequency of 2,000 to 5,000 per square centimeter. Common (C) represents a frequency of 500 to 2,000 per square centimeter. Infrequent (I) represents a frequency of 100 to 500 per square centimeter. Rare (R) represents a frequency of 10 to 100 per square centimeter. LITERATURE CITED Baker, Al , and Don Davison. 1966. Elk Lake — Routine Samples Correlated with Quantative Phytoplankton Samples. Itasca Biol. Station, Minn, (miraeo.). 1967. Personal Communication. Behre, K. 1956. Die Algenbesiedlung einiger Seen um Bremerhaven. V ev . Inst. f. Meeresforsah. Bremerhaven. 4: 221-283. Blum, John L. 1956a, The Ecology of River Algae. Bot. Rev. 22 (5) : 291-340. . 1956b. The Application of the Climax Concept to Algal Communities of Streams. Ecology. 37(3): 603-604. . 1957. An Ecological Study of the Algae of the Saline River, Michigan. Hydrobiol. 9(4): 361-408 Brook, Alan L. 1954. The Bottom-living, Algal Flora of Slow Sand Filter-Beds of Waterworks. Hydrobiol. 6(3) : 333-351. . 1955. The Attached Algal Flora of Slow Sand Filter Beds of Waterworks. Hydrobiol . 7:103-117. 1967. Personal Communication. Brezonik, P. L. , and C. L. Harper. 1969. Nitrogen Fixation in Some Anoxic Lacustrine Environments. Saience. 164: 1277-1279. 1970. Recent Limnological Conditions in Lake Mize, Florida. Report to School of Forestry, Univ. Florida. Castenholz, Richard W. 1957. Seasonal Changes in the Algae of Freshwater and Saline Lakes in the Lower Grand Coulee, Washington. Ph.D. Thesis, Washing- ton State Univ. - 199 - - 200 - . 1960. Seasonal Changes in the Attached Algae of Freshwater and Saline Lakes in the Lower Grand Coulee, Washington. Limnol. and Ooeanogr. 5(1): 1-28. Cooke, William B. 1956. Colonization of Artificial Bare Areas by Microorganisms. Bot. Rev. 22(9): 613- 638. Dor, Inka. 1970. Production Rate of the Periphyton in Lake Tiberias as Measured by Glass-slide Method. Israel Jour. Bot. 19(1): 1-15. Foerster, John W. 1964. The Synecology of Phyco-periphyton in Oligotrophic Lakes. Master's Thesis, North Texas State Univ. , and Harold E. Schlichting. 1965. Phyco- periphyton in an Oligotrophic Lake. Trans. Amer. Micros. Soa. 84(4): 485-502. Fogg, G. E. 1966. Algal Cultures and Phytoplankton Ecology . Univ. Wisconsin Press, Madison. Fritsch, F. E. 1929. The Encrusting Algal Communities of Certain Fast-flowing Streams. New Phytol. 28 (3) : 165-197. Godward, Maude. 19 37. An Ecological and Taxonomic Investigation of the Littoral Algal Flora of Lake Windermere. Jour. Ecol. 25(2): 496-568. Harkness, William J. K. , and E. Lowe Pierce. 1941. The Limnology of Lake Mize, Florida. Proa. Florida Acad. Sai. 5: 96-116. Hentschel , E. 1916. Biologische Untersuchungen iiber den Tierischen und Pflanzlichen Bewuchs in Hamburger Hafen. Mitt. Zool. Mus. Hamburg. 33: 1-172. Kny, L. 1884. Das Wachsthum des Thallus von Coleoohaete scutata in seinen Beziehungen zur Schwerkraft und zum Lichte. Ber. Deutsoh. Bot. Ges. 2: 93-96. Macan, T. T. 1970. Biological Studies of the English Lakes. Longmans Group Ltd., London. - 201 - Maciolek, J. A., and H. D. Kennedy. 1964. Spatial Variation in Periphyton Production in a Mountain Lake at Fall Overturn. Vevh. Internat. Verein. Limnol. 15: 386-393. Margalef, Ramdn. 1949a. A New Limnological Method for the Investigation of Thin-layered Epilithic Communities. Hydrobiol . 1: 215-216. . 1949b. Une Nouvelle Methode Limnologique pour L'dtude du Periphyton. Verh. Internat. Verein. Limnol. 10: 284-285. . 1953. Materiales para la Hidrobiologia de la Isla de Mallorca. Inst, de Biol. Applicada Barcelona. 15: 5-11. 1968. Perspectives in Ecological Theory. Univ. Chicago Press, Chicago. McWhorter , F. P., and E. Weier. 1936. Possible Uses of Dioxan in Botanical Microtechnique. Stain. Tech. 11:107-119. Neal, Ernest C, Bernard C. Patten, and Charles E. DePoe. 1967. Periphyton Growth on Artificial Substrates in a Radioactively Contaminated Lake. Ecology . 48 (6) : 918-923. Nordlie, Frank G. 1967. Chemical and Biological Dynamics in Two Solution Lakes. Final Report to the United States Department of the Interior, Federal Water Pollution Control Administration (mimeo.). Odum, Eugene P. 1959. Fundamentals of Ecology (2nd ed.). W. B. Saunders Co., Philadelphia. . 1969. The Strategy of Ecosystem Development. Science. 164: 262-270. Pearsall, W. H. 1917. The Aquatic and Marsh Vegetation of the English Lakes. Jour. Ecol. 5: 180-202. . 1920. The Aquatic Vegetation of the English Lakes. Jour. Ecol. 8: 163-201. - 202 - 19 21. The Development of Vegetation in the English Lakes, Considered in Relation to the General Evolution of Glacial Lakes and Rock Basins. ProG. Royal Soc. (B) 92: 259-284. , and T. Hewitt. 1933. Light Penetration into Fresh Water. 2. Light Penetration and Changes in Vegetation Limits in Windermere. Jour. Exp. Biol. 10: 306-312. Prowse , G. A. 19 59. Relationships Between Epiphytic Algal Species and Their Macrophytic Hosts. Nature. 186: 1204-1205. Round, F. E. 1964. The Ecology of Benthic Algae, pp. 138- 184. In Jackson (ed.). Algae and Man. Plenum Press, New York. . 1966. The Biology of the Algae. Edward Arnold Ltd . , London. Ruttner, Franz. 1963. Fundamentals of Limnology (3rd ed.), Univ. Toronto Press, Toronto. Sculthorpe, C. D. 1967. The Biology of Aquatic Vascular Plants. St. Martin's Press, N. Y. Shannon, E. E. 1970. Eutrophication-trophic State Relationships in North and Central Florida Lakes. Ph.D. Thesis, Univ. Florida. Sladeckova, Alena. 19 62. Limnological Investigation for the Periphyton ("Aufwuchs") Community. Bot. Rev. 28: 286-350. . 1966. The Significance of the Periphyton for Theoretical and Applied Limnology. Verh. Internat. Verein. Limnol. 16: 753-758. Tiffany, L. H. 1951. The Ecology of Fresh-water Algae, pp. 293-311. In G. Smith (ed.). Manual of Phycology. Chronica Bot. Co., Waltham, Mass. Whitford, L. A. 1956. The Communities of Algae in the Springs and Spring Streams of Florida. Ecology. 37 (3) : 433-442. - 203 - and G. J. Schumacher, 1963 Communities of Algae in North Carolina Streams and their Seasonal Relations. Hydrobiol. 22: 133-196. Young, Whitney. 1945. A Limnological Investigation of Periphyton in Douglas Lake, Michigan. Trans. Amer. Micros. Soc. 64(1): 1-20. Yount, James L. 1956. Factors that Control Species Number in Silver Springs, Florida. Limnol. and Oaeanogr. 1(4): 286-295. BIOGRAPHICAL SKETCH Helen Davis Brown was born in Charlotte, North Carolina, on March 23, 1934. She graduated from North Mecklenberg High School in 1952. Her undergraduate eduation was obtained at Mars Hill Junior College (A.A. , 1954) and Appalachian State Teachers College (B.S., 1956). The M.A. degree was also awarded her in 1959 by Appalachian State Teachers College after study during successive summers from 1957 to 1959. During the 19 66-19 67 academic year, graduate study in botany was begun at the University of Minnesota. A doctoral program in botany with a specialization in phycology was then initiated at the University of Florida in 1967, continuing through 1972. As a teacher in secondary schools prior to the majority of her graduate work, Helen Davis Brown held the following positions: Arlington Junior High, Gastonia, North Carolina (1956-1962) ; Woodbridge Junior High, RAF Woodbridge, England (1962-1964); and DeLaura Junior High, Satellite Beach, Florida (1964-1966). While at the University of Florida, she held a graduate assistantship from the Botany Department during the years 1967-1968 and 1971-1972 and a Graduate School - 204 - - 205 - Fellowship during the 1968-1969 academic year. From 1969- 1971 she also served in an interim appointment as an assistant professor of biology at Augusta College in Augusta, Georgia. I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. 'i^ ^L a:il. Chairman D/. Dana G. Gri'jniin, Assistant Professor of Botany I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Dr. Leland Shanor Professor and Chairman, Botany I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Hemry C. Aldrich Dr. Associate Professor of Botany I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Dr. yJames'lW. Kimbroughy As^ciate /Prof essor or Botany I certify that I have read this study and that in my opinion it conforms to acceptable standards of scholarly presentation and is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. )r. Frank G. Nordlie Associate Professor Zoology This dissertation was submitted to the Dean of the College of Agriculture and to the Graduate Council, and was accepted as partial fulfillment of the requirements for the degree of Doctor of Philosophy. August, 1972 of Agriculture Dean, Graduate School \t'