ABSTRACT
Planktonic communities The diversity of protozoa and the numbers of or ganisms in the water column of bodies of fresh water are usually a function of the amount of available organic matter. Oligotrophic lakes and over wintering lakes typically have a sparse community of organisms, but this gets richer during the pro ductive seasons and/or in richer eutrophic lakes. In enriched lakes, aggregates of bacteria and detritus may form in the water as a result of microbial activity; these aggregates may support a more diverse community which resem bles that found in and on the benthos.
