Ref ID : 6562
William B. Richardson; Seasonal dynamics, benthic habitat use, and drift of zooplankton in a small stream in southern Oklahoma, U.S.A. Can.J.Zool. 69:748-756, 1991
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Seasonal dynamics of zooplankton were examined in Rock Creek, a second-order stream in south central Oklahoma, U.S.A. Periodic samples were taken of zooplankton and environmental variables in a pool and in drift above and below the pool. A field manipulation was conducted to invesigate the role of benthic water movement and substratum angle of orientation as factors affecting microcrustacean densities on substratum in pools. Variation in densities of cyclopoid copepods and rotifers were best predicted by the product of pool retention time and water temperature (cyclopoids: r=0.91, P=0.0001; rotifer: r=0.90, P=0.001). Algal biomass was the best predictor of Cladocera densities (r=0.54, P=0.05). Pool retention time and water temperature had little direct effect on Cladocera densities. Microcrustacea and rotifers were imported into the pool during flooding and exported during low flow periods in the summer. Postflood pool densities decreased rapidly after flooding. Microcrustacea were most abundant on experimental vertical substrates in nonflowing areas (P(FxA)=0.0001). These substrates had the greatest epilithic biomass and chlorophyll a content. All microcrustacean and rotifers commonly occurring in the pool were associated with benthic and (or) littoral habitats. This habitat association is probably the primary mechanism for resisting downstream movement.