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The Phytoplankton Biomass and Species Composition at Two Stations in Western Lake Erie, 1975/76

1980; Wiley; Volume: 65; Issue: 5 Linguagem: Inglês

10.1002/iroh.19800650512

0020-9309

David William. Gladish, M. Munawar,

Aquatic Ecosystems and Phytoplankton Dynamics

Abstract Integrated phytoplankton samples from two stations in the northern waters of western Lake Erie were analyzed by the Utermöhl technique for the period from June, 1975 to September, 1976, with weekly sampling in the summer of 1975. No consistent differences were observed between the two stations. Two annual peaks were found: the first was a vernal pulse (1.4 to 4.8 g/m 3 ) comprised primarily of diatoms (86.0–95.7% of total biomass; principal species were Tabellaria fenestrata (Lyngb.) Kg., Stephanodiscus hantzschii Grun., and Fragilaria capucina Desm.); the second peak (3.1 to 9.9 g/m 3 ) was in late summer – early fall. This latter peak consisted of initially diatoms ( Coscinodiscus rothii Ehr. Grun. and Melosira granulata (Ehr.) Ralfs being the chief components), later dominated by bluegreens ( Aphanizomenon flos‐aquae (L.) Ralfs and Chroococcus minutus (Keutz.) Naegeli), and finally diatoms ( Coscinodiscus rothii, Stephanodiscus spp., Fragilaria crotonensis (Edw.) Kitton, and Melosira granulata). The importance of phytoflagellates (25.5 to 93.4% of total biomass), especially Gymnodinium sp., Cryptomonas erosa Ehrb., and Cryptomonas erosa v. reflexa Marsson., in June – early July samples and the overwhelming dominance of diatoms during the remainder of the year are stressed. No patterns in biomass and composition could be observed in vertical phytoplankton profiles. The present study provides an important connecting link between past and future studies performed with the standard Utermöhl technique.