Phytoplankton abundance in Florida lakes: Evidence for the frequent lack of nutrient limitation

A survey of the phytoplankton communities in 165 Florida lakes during 1980 indicated 27% of 308 samples collected had phytoplankton populations that were at or very close to their maximal achievable densities. This finding suggests that nonnutrient constraints including self-regulation by the algal community may be playing an important role in regulating phytoplankton biomass in many Florida lakes. Algal populations that were close to their maximal achievable densities had algal biomass values >10 mg liter−1 and Chl a concentrations >10 mg m−3. As nonnutrient constraints became more important, algal communities shifted from small-celled, diatom-green algal communities to communities dominated primarily by large, blue-green bacteria.