Publications Search - Publication Abstract, Illinois State Water Survey

Publication Abstract

Algae in Selected Illinois Streams, 1971-1976 Lin, Shundar, Ralph L. Evans, and Davis B. Beuscher, 1978  Illinois State Water Survey, Champaign, IL,  ISWS RI-86    Full Text Available

During the 5-year period, October 1971 through September 1976, samples of water from 21 Illinois streams at 26 locations were collected monthly and examined to determine the concentration and genera of algae. Data have been evaluated for algal composition, density, diversity indices, and seasonal succession for each stream location. At most sampling locations, algal densities ranged from 500 to 2000 cts/ml. The 5-year geometric means extended from 880 to 1500 cts/ml. From 24 to 30 different algal genera were recovered from each station and, in all, 56 genera were detected. The average diversity index for each station ranged from 1.11 to 1.36 bits per individual. The highest density of 60,000 cts/ml occurred on July 11, 1975, in the Fox River at Algonquin. The diatoms Navicula and Cyclotella were the most frequently observed algae. In addition to these, the green algae Scenedesmus and Crucigenia and the diatom Melosira were often dominant. From sample to sample, season to season, and year to year, the genera found at any sampling station varied considerably. Generally, the annual maximum population occurred in the spring. However, the experience gained from this study supports the conclusion that it is impossible to predict algal density, composition, or succession in the flowing streams of Illinois.

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