The crustacean zooplankton communities of three prairie lakes subject to varying degrees of anoxia

Abstract

The crustacean zooplankton communities in three small prairie lakes subject to varying degrees of anoxia were studied for 14 months from February 1976 to April 1977. Ten or twelve samples were collected with a tube in both the deep and shallow zones of each lake once weekly during summer, biweekly in spring and fall and monthly during winter. Local terrain was important to lake trophy and stratification. Physical and chemical observations indicated that shallow hypertrophic Lake 885 periodically stratified, exhibited winter and summer anoxia and had extreme nutrient and algal biomass levels. Shallow, meso-eutrophic Lake 255 was holomictic, displayed winter anoxia, and had lowest nutrient and phytoplankton amounts. Deeper, eutrophic Lake 019, stratified through summer, was not completely exhausted of oxygen and contained intermediate nutrient and algal concentrations. Dense populations of planktivorous fish Pimephales promelas and Culaea inconstans occurred in Lake 019 while Salmo gairdneri were stocked in Lakes 255 and 885... While large quantities of resting eggs were produced by D. siciloides in winterkilled Lake 255, considerably fewer eggs were carried by females surviving winter in oxygenated Lake 019. Relatively small differences in lake trophy and morphology appeared to effect considerable differences in oxygen conditions and seasonal crustacean plankton community composition and dynamics.