Spring Phytoplankton Abundance and Productivity in Grand Traverse Bay, Lake Michigan, 1970
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SubjectGrand Traverse Bay; Lake Michigan; Phytoplankton; Elk River; Boardman River; Michigan Sea Grant; Sampling; Standing Crop; Productivity
In May 1970, phytoplankton abundance in Grand Traverse Bay ranged from 1455 cells/ml to 3355 cells/mi. Highest standing crop estimates were obtained from stations in the lower portion of the west arm. Lowest standing crop estimates were obtained from stations in the upper east arm. The same populations dominated the assemblages at all stations and estimated diversity of assemblages was relatively high and uniform, ranging from 2.3 to 2.6, Estimates of primary productivity from the same stations ranged from 3.8 mg C m3 hr to 9.1 mg C m3 hr1 and followed the same general pattern of areal distribution as the standing crop estimates. In June, standing crop estimates increased significantly, with values ranging from 2500 cells/ml to 6469 cells/ml. Highest standing crops again were found at stations in the lower west arm, in the vicinity of Traverse City. Similar dominant populations were present again at all stations, but estimated diversity of the assemblages at all stations decreased, with values ranging from 1.8 to 2.2. Estimates of primary productivity were more variable during the June sampling period, with values ranging from 2.7 mg C m hr- 1 to 13.4 mg C m~3 hr- 1 , with greatest differences again being between most productive stations in the lower west arm and least productive stations in the upper east arm. (Key words: Phytoplankton;, standing crop; productivity; Grand Traverse Bay).
FIG. 1. Outline of Grand Traverse Bay showing station locations., TABLE 1. Productivity related parameters measured at 12 stations in Grand Traverse Bay, Lake Michigan on 18 May and 20 June 1970. Bracketed values derived from samples taken 1 m above bottom; others are derived from samples taken at 5-m depth., TABLE 2. Relative frequency of dominant taxa in samples from 5 m depth, Grand Traverse Bay, Lake Michigan on 18 May and 20 June 1970. A = Synedra filiformis Grün B Unident. flagellates; C = Melosira islandica O. Mull.; D = Fragiaria crotnensis Kitton; E = Rhizosolenia gracilis H. L. Smith; F = Steplianodiscus minutus Grun.; G = Cyclotella stelligera (Grun. & CI.) V. H.; H = Tabellaria fenestrata (Lyngb.) Kütz.; I = Rhizosolenia eriensis H. L. Smith; J = Cyclotella michiganiana Skv.; K = Melosira italica subsp. subarctica O. Müll.; L = Asterionella formosa Hass.; Species = Total number of species in sample; Div. = Diversity; Tot. % = Percent of assemblage accounted for by dominants., TABLE 3. Relative frequency of pollution tolerant taxa in samples from 5 m depth, Grand Traverse Bay, Lake Michigan collected on 18 May and 20 June 1970.