The effect of soluble phosphorus on the standing crops of phytoplankton and zooplankton in ten lakes.

Abstract

In our study we looked at the complex interactions between biotic and abiotic factors in lake ecosystems. Specifically we examined the effect of soluble phosphorus on phytoplankton and zooplankton biomasses. Since soluble phosphorus is commonly the limiting nutrient for phytoplankton in freshwater lakes and phytoplankton are the main food source for zooplankton we expected positive correlation between soluble phosphorus and these two variables. We sampled ten lakes in Cheboygan County in order to measure the soluble phosphorus concentrations, chlorophyll-a concentrations and zooplankton biovolume. A regression analyses showed no significant correlations between any of our variables. We found several explanations consistent with these results, including the fluctuations in phosphorus availability and predations on both phytoplankton and zooplantkon.