Size distribution of planktonic autotrophy and microheterotrophy in DeGray and West Point reservoirs: a comparative study. Final report

Particle size is an important determinant of food resources available to planktonic consumers and of the efficiency of energy transfer through planktonic foodwebs. Thus, the environmental factors controlling the size distributions of planktonic autotrophy (algal photosynthesis) and microheterotrophy (bacterial heterotrophic activity) are of considerable ecological interest. To examine hypotheses regarding their environmental control, we compared the size distributions of planktonic autotrophy and microheterotrophy within and between oligotrophic DeGray Reservoir (Arkansas) and eutrophic West Point Reservoir (Alabama-Georgia). Naturally occurring assemblages of reservoir phytoplankton and bacterioplankton were radiolabeled with sodium /sup 14/C-bicarbonate and sodium /sup 3/H-acetate and were size fractionated by filtration through polycarbonate membrane filters. 92 refs., 12 figs., 7 tabs.