Seasonal Distribution of Phytoplankton Biomass in a Nearshore Area of the Central Basin of Lake Erie, 1975-19761

SEASONAL DISTRIBUTION OF PHYTOPLANKTON BIOMASS IN A NEARSHORE AREA OF THE CENTRAL BASIN OF LAKE ERIE, 1975-19761

JOHN E. REUTER2, Great Lakes Laboratory, State University College at Buffalo, Buffalo, New York 14222

Abstract. Samples for the analysis of seasonal distribution of phytoplankton biomass were collected on 10 occasions between July 1975 and June 1976. Samples were taken from 3 depths in the euphotic zone at 5 nearshore stations in Lake Erie near Ashtabula, Ohio. A bimodal pattern of distribution was observed with fall and spring maxima and the dominance of Bacillariophyceae. Although the maxima were equal in magnitude, the fall peak was longer in duration and was dominated by Stephanodiscus niagarae and Pediastrum simplex. The spring biomass peak was observed on a single collection date and was composed principally of Stephanodiscus niagarae, Skeletonema subsalsum, Melosira italica and Cyclotella sp. The Cryptophyta were common throughout the study while representatives of the Cyanophyta and Pyrrhophyta were only abundant in a single collection. The occurrence and distribution of Skeletonema subsalsum (Bacillariophyceae) are discussed.

OHIO J. SCI. 79(5): 218, 1979

Increased attention has been given to MATERIALS AND METHODS the seasonal distribution of phytoplank- Phytoplankton samples were taken at ap- ton sampled from the nearshore area of proximately 4 week intervals from July to November 1975 and from April to June 1976 at the Central Basin of Lake Erie. Al- 5 stations (fig. 1). Water was collected with a though early studies date back to Vorce Van Dorn bottle at 3 depths in the euphotic (1881) and Burkholder (1929), compre- zone: 1 m below the surface and the depths cor- hensive research was sparse until Davis responding to 25% and 1% of the surface light transmission. Light transmittance was de- (1954a, b, 1962, 1964, 1965) began a termined using a Kahlsico #268WA310 Photo- series of investigations in the Cleveland metric Submarine Photometer. Due to natural Harbor area. More recent studies, which variations in solar illumination, changes in have focused on the American nearshore, cloud cover and water turbidity, the depth of 1% surface light tranmsittance ranged from include: FWPCA (1968), Hartley and 18 m (bottom) on 30 July to 3 m on 16 No- Potos (1972), Rietz (1973), Garlauskas vember. Composite samples were made for (1974), Great Lakes Laboratory (1974) each station by combining equal volumes of and Munawar and Munawar (1975, water from each of the 3 depths sampled for phytoplankton identification and enumeration. 1976). In addition, Michalski (1968) in- Samples were preserved in Lugol's solution vestigated the phytoplankton of the (Vollenweider 1969). Canadian nearshore. The present re- The laboratory procedure employed for port examines both quantitative and phytoplankton analysis was that of Utermohl qualitative aspects of phytoplankton (1958) as modified by Lorefice (1974). De- biomass seasonal distribution in the pending on algal and inorganic particulate density, 10-50 ml of unconcentrated lake water nearshore region (between 20 m isopleth was settled for 24 hours and phytoplankton and the shoreline) of Lake Erie in the taxa were counted at 300X with a Wild Heer vicinity of Ashtabula, Ohio. burg (M-40), Phase Contrast, Inverted Micro- scope. A minimum of 300 cells were enume- rated for each sample (Lund et til 1958). Algal Manuscript received 22 May 1978 and in re- biomass was calculated by taking the average vised form 14 March 1979 (//78-27). dimensions of individual organisms for each 2Present address: Department of Environ- collection period and computing the volume of mental Studies, University of California at the geometric form which best fit the shape of Davis, Davis, CA 9561 (>. the cells measured. This volume was subse- 218 Ohio J. Sci. LAKE ERIE CENTRAL BASIN PHYTOPLANKTON 219 quently converted to biomass assuming the den- certain; therefore, these organisms were sity of an algal cell to be similar to that of grouped together under the category unidenti- water, 1.0 g/ml (Willen 1959). When colonial fied flagellates. forms were encountered, the average number of cells/colony was calculated and multiplied by RESULTS the cell volume to obtain the volume/colony. Between 25 and 60 cells were measured to ac- Species composition. A total of 86 count for the natural diversity of size in indi- algal taxa were identified during the viduals comprising the phytoplankton com- investigation (table 1), a detailed listing munity. Biomass computations were made only on organisms that were found more than 3 which is presented in Reuter (1977). times in a single sample. The Chlorophyta represented the most To deal with the numerous problems associ- diverse division with 43 taxa encountered.

PW 1

FIGURE 1. Location of sampling stations in the nearshore area of the Central Basin of Lake Erie in the vicinity of Ashtabula, Ohio. ated with horizontal heterogeneity (patchiness) Within this division, the members of the of phytoplankton in Lake Erie (Verduin 1951, Davis 1962), estimates of biomass were reported Chlorococcales were most common (36 as a mean for the five stations sampled. Fur- taxa). The number of taxa representing ther attempts were made to reduce the sampling the Bacillariophyceae (19 taxa), Cyano- error due to patchiness by taking triplicate sam- phyta (10 taxa) and Cryptophyta (5 ples in 1975 and duplicate samples in 1976. These procedures would yield a more realistic taxa) was relatively moderate. The measure of actual phytoplankton populations Chrysophyceae, Pyrrhophyta and Eugle- because of the continual motion of water within nophyta contributed very little to the the nearshore lacustrine environment. total number of observed taxa. Diatom identification was facilitated by the use of permanent slides which were prepared by Seasonal variation of total phytoplank- heating a concentrated sample and a few drops ton. The investigation was initiated on of H2O2 on a glass slide followed by mounting in Hyrax (Munawar and Munawar 1976). The 10 July 1975 with the first 3 collection species identification of Skeletonema subsalsum dates occurring during what appeared to was kindly done by Dr. Grethe R. Hasle (Uni- be a period of summer minimum (fig. 2). versity of Norway). On each collection date, Total phytoplankton biomass steadily small (<10M) flagellated cells were found which decreased from 804 mg/m3 on July 10 to could not be positvely identified. Although 3 many of these cells may have belonged to the a minimum of 321 mg/m on August 19. class Chrysophyceae, identification was un- The distribution of the major algal groups 22 0 JOH N E . REUTE R Vol 7 9 TABLE 1 Seasonal Distribution of Total Phytoplankton Biomass and Associated Major Taxa.

1975 1976 Taxa Collection da te 7/10 7/30 8/19 9/14 10/19 11/16 4/9 4/20 5/15 6/10

BACILLARIOPHYCEAE 428(7)* 132(7) (5) 1146(11) 1005(11) 1178(9) 512(17) 54(13) 1562(15) (1) A sterionella formosa OK Cyclotella sp. 224 Fragilaria crotonensis 403 132 — 56 — — 40 — — — Melosira italica — — — — — — — — 289 Skeletonema subsalsum — — — — — 340 Stephanodiscus binderanus — — — — — — 217 22 56 — S. niagarae — — — 1025 836 1037 — — 613 — Surirella sp. — — — — — — 65 — — — Others — — — 65 169 141 134 32 — — CHLOROPHYTA 70(24) 365(33) 182(32) 430(29) 799(23) 354(26) 119(18) 139(18) 83(16) 29(6) Chlamydomonas globasa — — — — — 8 119 125 41 13 Coelastrum reticulatum — — 18 18 17 14 — — — — Oocystis spp. 38 272 22 37 19 11 — — 14 — Pediastrum simplex — 24 80 244 624 191 — — — — Scenedesmusbijuga var. flexuosas 10 26 19 144 29 69 — — — — Sphaerocystis schroeteri — 15 31 — — — — — — —. Others 22 28 12 17 110 61 — 14 28 16 CRYPTOPHYTA 270(5) 110(5) 100(5) 119(5) 255(5) 370(5) 47(4) 270(5) 383(5) 270(5) Cryptomonas erosa 197 45 46 77 142 247 — 98 179 155 C. marssonii 8 5 — 12 20 44 — — — 40 Katablepharis ovalis 6 3 7 4 9 8 13 7 8 33 Rhodomonas minuta 41 57 47 26 37 50 34 165 196 42 Others 18 — — — 47 21 — — — — CYANOPHYTA 15(3) 20(4) 14(7) 16(9) 114(5) 11(3) — — 14(2) 2(1) Anabaena spp. 4 8 6 2 29 .3 — — Aphanizomenon flos-aquae 8 12 8 14 85 8 — — 14 — Others 3 — — — — — — — — 2 CHRYSOPHYCEAE 2(1) 2(2) 5(1) 3(1) 1(1) 1(1) 10(2) 18(3) (1) 54(2) Chrysochromulina parva 2 2 5 3 1 1 — 9 54 Dinobryon spp. —• — — — — — 10 9 — — PYRRHOPHYTA (2) (1) (2) (2) (2) (3) (1) 265(1) — —. Peridinium aciculiferum —• — — 265 — — EUGLENOPHYTA — — — — — — (2) — (1) — Unidentified flagellates 19 26 20 35 96 41 49 147 154 105 TOTAL 804(42) 655(52) 321(52) 1749(57) 2270(47) 1955(47) 757(45) 893(43) 2196(40) 460(15)

* Values are mg/m3 and numbers in parentheses ( ) show the total number of taxa found on a given collection date. Ohio J. Sci. LAKE ERIE CENTRAL BASIN PHYTOPLANKTON 221 also differed during this period (fig. 2). mass was similar on April 20 (893 mg/m3), On July 10 the Bacillariophyceae and community composition changed (fig. 2). Cryptophyta were the most abundant The Cryptophyta and Pyrrhophyta domi- phytoplankters. By July 30 the Bacil- nated the phytoplankton, while the lariophyceae had declined and the Chlo- Chlorophyta and unidentified flagellates rophyta became the dominant algal contributed lesser numbers. The May group. In the August 19 samples, only 15 sample was characterized by a large the Chlorophyta were present in ap- increase in biomass (2196 mg/m3). The preciable quantities. Bacillariophyceae were by far the most

BIOMASS BACILLARIOPHYCEAE

CHLOROPHYTA

CRYPTOPHYTA

CYANOPHYTA

CHRYSOPHYCEAE

PYRRHOPHYTA

UNIDENTIFIED FLAGELLATES FIGURE 2. Seasonal distribution of total phytoplankton biomass and associated major algal groups.

During the fall collection dates (Sept. abundant group, but the Cryptophyta 14, Oct. 19, Nov. 16) a biomass maximum were again present in substantial quanti- was observed. Biomass values rose to ties. In what appeared to be a return to 1749 mg/m3 on Sept. 14 and remained the summer minimum, biomass dropped high during the two subsequent sampling to 460 mg/m3 on June 10 with the dates (2270 mg/m3 on Oct. 19 and 1955 Cryptophyta and unidentified flagellates mg/m3 on Nov. 16. Due to the limited dominating the biomass. sampling regime, the exact duration of Seasonal variation of the major algal the biomass maximum was impossible to groups and common species. The Bacil- determine. The Bacillariophyceae were lariophyceae were the most abundant the most abundant phytoplankters dur- phytoplankters and a definite bimodal ing the fall, and Chlorophyta biomass pattern of seasonal distribution was ob- was also high at that time. The com- served with maxima occurring in the fall position of the phytoplankton community and spring (table 1,2). On July 10, Bacil- remained relatively uniform on the 3 lariophyceae biomass was 428 mg/m3 of collection dates with the exception of an which Fragilaria crotonensis contributed increase of Cyanophyta on Oct. 19th. 403 mg/m3. A marked reduction in bio- On the first collection during the mass (132 mg/m3) was observed on July spring of 1976 (April 9) a phytoplankton 30 when F. crotonensis was the only biomass of 737 mg/m3 was observed of taxon encountered. By August 19 this which the Bacillariophyceae were domi- group was absent from the samples. nant taxa encountered. Although bio- During the fall collection dates biomass 222 JOHN E. REUTER Vol. 79 increased to approximately 1100 mg/m3. posed the Bacillariophyceae community This increase was singularly attributable with no single taxon dominating. On to Stephanodiscus niagarae obtaining bio- April 9, Stephanodiscus binderanus, Suri- mass values ranging from 836 to 1037 rella sp., A sterionella formosa and Fragi- mg/m3. The spring collections of 1976 laria crotonensis were the most common differed from the 1975 summer and fall taxa contributing 512 mg/m3 to the bio- collections in that a variety of taxa com- mass. Biomass decreased to less than 100 mg/m3 on April 20. A spring in- TABLE 2 crease was observed on May 15 when Seasonal Distribution of the Most Common algae Bacillariophyceae biomass dramatically Which Contributed 5% or More to the Total increased to 1562 mg/m3, the highest bio- Phytoplankton Biomass. mass value for any major algal group during the investigation. Stephanodiscus Collection Mean % niagarae, Cyclotella sp., Melosira italica Date Species Biomass and Skeletonema subsalsum were the 7/10/75 Fragilaria crotonensis 50.1 major constituents of the phytoplankton Cryptomonas erosa 24.7 during the biomass maximum. With the Oocystis spp. 5.4 exception of S. niagarae, the dominant Rhodomonas minuta 5.2 Bacillariophyceae observed during the 7/30/75 Oocystis spp. 42.4 Fragilaria crotonensis 20.0 spring were not encountered during the Rhodomonas minuta 9.8 other collection dates. The spring di- Cryptomonas crosa 6.7 atom increase was observed only on May 8/19/75 Pediastrum simplex 25.9 15 and, by June 10, no Bacillariophyceae Rhodomonas minuta 14.6 Sphaerocystis schroeteri 9.5 were found in the samples. Cryptomonas erosa 9.3 A unimodal pattern of distribution Oocystis spp. 7.3 with a definite fall maximum was ob- Scenedesmus bijuga var. flexuosus 6.0 served for the Chlorophyta (table 1). A Cryptomonas marssonii 5.7 number of taxa were abundant in the Coelastrum reticulatum 5.0 summer and fall collection; while very 9/14/75 Stephanodiscus niagarae 58.7 few were encountered during the spring. Pediastrum simplex 14.5 On July 10, biomass was low (70 mg/m3) Scenedesmus bijuga var. with Oocystis spp. as the dominant taxa. flexuosus 6.6 3 10/19/75 Stephanodiscus niagarae 36.9 Biomass increased to 365 mg/m on July Pediastrum simplex 27.6 30 due to a large increase of Oocystis spp.; Cryptomonas erosa 6.3 Aphanizomenon flos-aquae 5.1 Pediastrum simplex var. duodenarium, 11/61/75 Stephanodiscus niagarae 53.3 Sphaerocystis schroeteri and Scenedesmus Cryptomonas erosa 12.7 bijuga var. flexuosus were also present on Pediastrum simplex 10.1 this date but in lesser quantities. By 4/ 9/76 Stephanodiscus binderanus 28.7 Chlamydomonas globosa 16.1 August 19, total Chlorophyta biomass Stephanodiscus tennis 11.0 decreased as did that of Oocystis spp. Surirella sp. 9.9 The fall samples were characterized by A sterionella formosa 6.8 large increases in Pediastrum simplex var. 4/20/76 Peridinium aciculiferum 35.1 duodenarium and to a lesser extent, Rhodomonas minuta 18.0 Chlamydomonas globosa 14.5 Scenedesmus bijuga var. flexuosus. On Cryptomonas erosa 11.2 Oct. 19, a maximum biomass of total 5/15/76 Stephanodiscus niagarae 27.6 Chlorophyta (799 mg/m3) and Pedi- Skeletonema subsalsum 15.6 astrum simplex var. duodenarium (624 Melosira italica 14.4 3 Cyclotella spp. 10.2 mg/m ) was observed. Pediastrum sim- Rhodomonas minuta 8.8 plex var. duodenarium biomass decreased Cryptomonas erosa 8.3 on Nov. 16 and was associated with a Unidentified Flagellates 6.9 decline in total Chlorophyta biomass. 6/10/76 Cryptomonas erosa 32.1 The spring collections were quite different Unidentified Flagellates 26.4 in both quantity and composition. On Chrysochromulina parva 11.0 3 Rhodomonas minuta 8.8 April 9, biomass was only 119 mg/m Cryptomonas marssonii 7.7 with only Chlamydomonas globosa ob- Katablepharis ovalis 7.0 served. Chlamydomonas globosa re- Ohio J. Sci. LAKE ERIE CENTRAL BASIN PHYTOPLANKTON 223 mained the dominant taxon for the dura- 20 and remained fairly uniform at ap- tion of the spring collections but was proximately 120 mg/m3 for the remainder virtually absent from the summer and of the study. The only collection in fall samples. Oocystis spp. was again which the Pyrrhophyta were encountered observed on May 15 and June 10 but in was April 20 when a biomass of 265 reduced numbers. mg/m3 was observed with only Peri- Although 5 species of Cryptophyta dinium aciculiferum occurring in the were identified, only Rhodomonas minuta sample. and Cryptomonas erosa contributed ap- Chrysochromulina parva and Dino- preciably to the total biomass of this di- bryon spp. were the only Chrysophyccae vision (table 1). Cryptomonas erosa (197 taxa identified in the samples, with their mg/m;!) was the dominant species on biomass never greater than 60 mg/m3 on July 10, while total Cryptophyta biomass any collection date (table 1). Although was 270 mg/m:!. Values decreased to Chrysochromulina parva was observed in approximately 110 mg/m3 by July 30 and each of the summer and fall samples, its remained relatively uniform for the next biomass was negligable (<10 mg/m3). three collection dates. In these samples, Biomass values increased slightly on both Rhodomonas minuta and Crypto- April 9 and April 20 due to the occur- monas erosa occurred in nearly equal rence of Dinobryon spp. which was ob- numbers. Biomass increased to 255 served only on these two dates. The mg/m3 and 370 mg/m3 on Oct. 19 and two taxa were absent from the May 15 Nov. 16 respectively. This increase was samples. On June 10, Chrysochromulina attributed to an increase in biomass of parva biomass increased to nearly 55 Cryptomonas erosa which was the domi- mg/m3 during what appeared to be a nant cryptomonad found at that time. bloom condition. At that time, cell con- A decrease in biomass occurred during centrations were greater than 4000 cells/ the first spring sampling; and, for the ml, the highest values observed for a first time in the study, Cryptomonas erosa single species in this study. was not observed. On April 20 total Crypotphyta biomass increased to 270 DISCUSSION 3 mg/m and was associated with an in- Previous observations of phytoplank- crease of Rhodomonas minuta. Biomass 3 ton distribution in the Central Basin lack values again increased to 383 mg/m on uniformity of 1. sampling location, 2. May 15 at which time Rhodomonas minuta method of phytoplankton collection and and Cryptomonas erosa were present in concentration, and 3. method of calculat- nearly equal numbers. A biomass de- 3 ing standing crop abundance. In past crease to 270 mg/m was observed on studies, sampling location varied from June 10. Katablepharis ovalis and Cryp- water taken at a single fixed point such tomonas marssonii were the major con- as water intake systems (Davis 1964, tributors to the Cryptophyta population Michalski 1968, Rietz 1973) to synoptic during this sampling period. multi-station sampling (Davis 1954a, Except for the October 19 collection 1962, Great Lakes Laboratory 1974). when a biomass of 114 mg/m3 was ob- Earlier studies also differed with respect served, the Cyanophyta were virtually to sampling depth and geographic loca- absent from the samples (table 1). For tion. The results of studies based on the remaining collection dates, Cyano- various methods of phytoplankton col- phyta biomass never exceeded 20 mg/m3. lection (net samples and whole water Aphanizomenon flos-aquae was the most samples) and concentration (settling, common taxa encountered, while Ana- straining and centrifugation) are not di- baena spp. occurred less commonly. rectly comparable to the present study. Due to the small size of the unidentified Estimates of phytoplankton abundance flagellate cells, their biomass values were using microscopic techniques have been relatively small (table 1). For the sum- expressed in numerous ways, including mer and fall samples, biomass never ex- cell number, cell volume or biomass and ceeded 60 mg/m3. Biomass values of the cell surface area. Due to the great di- unidentified flagellates increased on April versity in phytoplankton size, the results 224 JOHN E. REUTER Vol. 79 of these studies are difficult to directly Individual phytoplankters as well as compare. Therefore, only the general major algal groups demonstrated pat- trends of phytoplankton abundance and terns of seasonal succession during this composition will be discussed in relation investigation. Fragilaria crotonensis was to past investigations. a dominant taxon during the summer The bimodal pattern of distribution collection periods as well as Oocystis spp. observed in my study was in agreement Large quantities of Fragilaria crotonensis with that reported by Davis (1954a, 1962) were found only on July 9 and 30 collection and the Great Lakes Laboratory (1974). dates. Munawar and Munawar (1976) Periods of maximum biomass were ob- found large amounts of this species in served by these investigators in the June-July 1970, but also observed F. spring (March-May) and fall (September- crotonensis in high numbers through the November). Other researchers, examin- month of September. ing the nearshore phytoplankton of the Following the summer biomass mini- Central Basin, have reported the occur- mum, a fall maximum was observed first rence of trimodal peaks. Munawar and on September 14. On the collection dates Munawar (1975) observed periods of from September 14 to November 16, both maximum phytoplankton abundance dur- phytoplankton composition and biomass ing April, July-August, and December; remained relatively constant. The domi- while periods of minimum concentration nant taxa observed during that period were observed in May and October. were, the diatom, Stephanodiscus niagarae Garlauskas (1974) observed a single peak and the green alga Pediastrum simplex in September composed primarily of the var. duodenarium. These taxa were also genus Ceratium. found to be dominant fall phytoplankters The seasonal succession of the major in previous years (Davis 1962). Muna- algal groups during the 1975-1976 sur- war and Munawar (1975) report that vey were similar to that previously re- Stephanodiscus niagarae contributed 56% ported by Davis (1962) and Munawar of the biomass in the fall, while the per- and Munawar (1975, 1976). During cent composition of Pediastrum simplex 1975-1976, the Pyrrhophyta were never was somewhat lower than that reported found to be important contributors to in this study. The abundance of the phytoplankton biomass. This was ob- Cyanophyta in the fall was also in agree- served by Davis (1954a, 1962) and the ment with past reports of the seasonal Great Lakes Laboratory (1974); while distribution of this group. Munawar and Munawar (1975) found this group to be relatively abundant in For both the summer and fall collec- July, September and November. tions a large number of taxa belonging to Quantitatively, the biomass values re- the Chlorophyta were important con- ported in the present study were contributors to total biomass; while, during siderably lower than those of other in- the spring collections, Chlamydomonas vestigations. The Great Lakes Lab- globosa was the single dominant species. oratory (1974) reported biomass values Also during the spring sampling period, a in the range of 900-5700 mg/m3 for the number of algae were observed that were nearshore area in the vicinity of Cleve- not encountered in the summer or fall land, Ohio; while Munawar and Munawar collections. These taxa included: Peridi- (1975) note values between 2000-8000 nium aciculiferum, Stephanodiscus bin- mg/m3 for the same geographic area. deranus, Skeletonema subsalsum, Melosira Glooschenko et al (1974) encountered italica, Surirella sp. and Cyclotella sp. higher values of chlorophyll a in the Along with Stephanodiscus niagarae, other vicinity of Cleveland than in most other algae that were abundant during the areas of the Central Basin and attributed May 15 biomass maximum were Melosira this to nutrient discharge into the sur- italica, Skeletonema subsalsum, Cyclotella rounding waters. This explanation pos- sp., Rhodomonas minuta and Crypto- sibly may be applicable for the differences monas erosa. It is interesting to note observed in phytoplankton biomass be- that the spring maximum was composed tween Ashtabula and Cleveland. of a number of abundant phytoplankters Ohio J. Sci. LAKE ERIE CENTRAL BASIN PHYTOPLANKTON 225 while only two species were prevalent B. Plankton and Benthos data. Ohio State during the fall maximum. University, Columbus, OH. 281 p. Davis, C. C. 1954a A preliminary study of The occurrence of Skeletonema sub- the plankton of the Cleveland Harbor area, salum in Lake Erie was recently reported Ohio. II. Distribution and quantity of (Hasle and Evensen 1975), and data on phytoplankton. Ecol. Monog. 24: 321-347. its seasonal abundance and distribution 1954b A preliminary study of the plankton of the Cleveland Harbor area, are limited. A related species, Skele- Ohio. III. The zooplankton, and general tonema potamos ( = Microsiphonia pota- ecological considerations of phytoplankton mos), was reported from the Western and zooplankton production. Ohio J. Sci. Basin of Lake Erie by the Center for Lake 54: 388-408. 1962 The plankton of the Cleveland Erie Area Research (1975); however, be- Harbor area of Lake Erie in 1956-57. Ecol. cause these two species are morphologic- Monog. 32: 209-247. ally similar and have been found to occur 19G4 Evidence for the eutrophication together in Lake Erie (Hasle and Evensen of Lake Eric from phytoplankton records. Limnol. Occanogr. 9: 275-283. 1976), no attempt was made during the 1905 The standing stock of phyto- present study to separate them taxo- plankton in Lake Erie at Cleveland, Ohio, nomically. According to Haslc, one rea- 1964. Info. Bull. Planktol. Japan 12: 51-53. son for the lack of published records for Federal Water Pollution Control Administra- tion (FWPCA) 1968 Lake Erie environ- freshwater species of the genus Skele- mental summary, 1963-1964. U.S. Dept. tonema might have been a possible con- Interior, Great Lakes Region. Cleveland fusion between this genus, Melosira and Program Office, pp. 112-120, 137-143. Stepahnodiscus. This may account for Garlauskas, A. B. 1974 Water quality base- the lack of observations of Skeletonema ment for the Cleveland area-Lake Erie. Vol. I. Synthesis. Office of the Great during previous investigations in the Lakes Coordinator. U.S.E.P.A. Region V, Central Basin. Chicago, 111. 158 p. Munawar and Munawar (1975, 1976) Glooschenko, W. A., J. E. Moore and R. A. Vollenweider 1974 Spatial and temporal stressed the importance of phytoflagel- distribution of chlorophyll a and pheopig- lates in Lake Erie. In the present study, ments in surface waters of Lake Erie. J. the distribution of the Cryptophyta was Fish. Res. Board Canada 31: 265-274. unique with respect to the other major Great Lakes Laboratory 1974 Airport feasi- bility study for the Lake Erie Regional algal groups in that members of this Transportation Authority. State University group were present throughout the in- College, Buffalo, NY. Report No. 6-5. pp. vestigation in relatively uniform quanti- 43-53, 229-240, 242. ties. This pattern of distribution is in Hartley, R. P. and C. P. Potos. 1972 Algae- temperature-nutrient relationships and dis- general agreement with that of Munawar tribution in Lake Erie, 1968. U.S.E.P.A. and Munawar as was the large biomass of Federal Water Quality Administration. Chrysochromulina parva observed in June. Great Lakes Region, Lake Erie Basin Office, Cleveland, OH. 87 p. Acknowledgments. This study was part of an Hasle, G. R. and D. L. Evensen 1975 Brack- M.A. thesis submitted to the Biology Dept., ish-water and fresh-water species of the State University College at Buffalo, Buffalo, diatom genus Skeletonema Grev. I. Skele- New York. I am grateful to R. W. Flint and ionema subsalsum (A. Cleve) Bethge. Phy- R. A. Sweeney for their advice and encourage- cologia. 14: 283-297. ment and to V. R. Frederick and R. A. Sweeney 1976 Brackish-water and fresh-water for reading and commenting on this manuscript. species of the diatom genus Skeletonema. II. I am also indebted to the staff of the Great Skeletonema potamos. J. Phycol. 1: 73-82. Lakes Laboratory for their assistance in the Lorefice, G. J. 1974 Phytoplankton biomass collection of samples. Funding for this research and the thermal bar for the surface waters of was provided through a contract to the Great Southwestern Lake Ontario, April to May Lakes Laboratory by the Waterways Experi- 1972. Unpublished M.A Thesis, Bio. Dept., ment Station of the U.S. Army Corps of En- State University College, Buffalo, NY. 68 p. gineers (Grant #21-6010-A). Lund, J. W. G., C. Kipling and E. O. LeCren 1958 The inverted microscope method of LITERATURE CITED estimating algal numbers and the statistical Burkholder, P. R. 1929 Microplankton stud- basis of estimating by counting. Hydro- ies in Lake Erie. Bull. Buffalo Soc. Nat. Sci. biologia9: 143-170. 14: 73-93. Michalski, M. F. P. 1968 Phytoplankton Center for Lake Erie Area Research 1975 levels in Canadian nearshore waters of the Aquatic ecology investigations of a potential lower Great Lakes. Proc. Conf. Great power plant site on Sandusky Bay. Appendix Lakes Res. 11: 85-95. 226 JOHN E. REUTER Vol. 79

Munawar, M. and I. F. Munawar 1975 The Utermohl, H. 1958 Zur Verlkommungder abundance and significance of phytoflagel- quantitatven phytoplankton. Methodik. lates and nannoplankton in the St. Lawrence Mitt. Int. Verein. Limnol. 9: 1-38. Great Lakes. I. Phytoflagellates. Verh. Verduin, J. 1951 A comparison of phyto- Int. Verein. Limnol. 19: 705-723. plankton data obtained by a mobile sampling 1976 A lakewide study of Phyto- method with those obtained from a single plankton biomass and its species composition station. Amer. J. Bot. 38: 5-11. in Lake Erie, April-December, 1970. J. Fish. Vollenweider, R. A. 1969 A manual on meth- Res. Board Canada 33: 581-600. ods for measuring primary production in Reuter, J. E. 1977 Studies of phytoplankton aquatic environments. IBP Handb. No. 12. seasonal distribution in a nearshore area of Blackwell Scientific Publications, Oxford. the Central Basin of Lake Erie, 1975-1976. 213 p. Unpublished M.A. Thesis, Bio. Dept., State Vorce, C. M. 1881 Forms observed in waters University College, Buffalo, NY. 78 p. of Lake Erie. Proc. Amer. Soc. Micros. 4th Rietz, R. D. 1973 Distribution of phyto- Annual Meeting, pp. 51-60. plankton and coliform bacteria in Lake Erie. Willen, T. 1959 The phytoplankton of Gor- Ohio E.P.A., Division of Surveillance, walm, a bay of Lake Malaren. Okios 10: Columbus, OH. 67 p. 241-274.