Ref ID : 1851
Arthur V. Brown, Robert L. Limbeck, and Mark D. Schram; Trophic importance of zooplankton in streams with alluvial riffle and pool geomorphometry. Arch.Hydrobiol. 114(3):349-367, 1989
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This study assessed the potential trophic significance of zooplankton in a stream ecosystem that has distinct riffle and pool geomorphology. Quantitative samples were taken in the first five orders of an alluvial gravel bed stream, the Illinois River, Arkansas, USA. A manipulative experiment was performed in a third order reach to determine if plankton resources were utilized by net-spinning caddisfly larvae, Cheumatopsyche. An abundant, diverse zooplankton community comparable to that of local reservoirs was present in the headwaters, especially where flow through pools was <0.02 m/sec. An inverse relationship between plankton density and flow rate was observed among pools where flow was >0.05 m/sec. Significant (p<0.05) quantities of plankters were produced within pools and then removed as the stream flowed across second and third order riffles. The instream experiment reveled that substrate colonized by Cheumatopsyche removed significantly (p<0.05) more of the plankton at midnight than substrate alone, but not at middlay. Both treatments removed considerable plankton. Fewer zooplankton were collected from downstream sites (orders three through five). This was partially attributed to increased predation by planktivorous fish. Zooplankton apparently increase the food quality of seston in streams, especially those have areas of sufficiently slow flow rates.