The relationship between zooplankton community structure and lake characteristics in temperate lakes (Northern Wisconsin, USA)

Abstract

Zooplankton community structure can be affected by within-lake and by watershed ecological factors, including water chemistry (related to landscape position), lake morphology and human activity in the watershed. We hypothesized that all three groups of drivers would be correlated with zooplankton species richness and species composition for lakes in northern Wisconsin. Data collected from 52 lakes allowed us to explore the relationship of zooplankton community structure with ecological drivers. We found that crustacean zooplankton species richness was not significantly correlated with independent environmental variables derived from PCA ordination, nor with measures of community structure based on NMS ordination. However, species composition was correlated with environmental gradients. Larger zooplankton species (Daphnia pulicaria, Epischura lacustris, Skistodiaptomus oregonensis, Mesocyclops americanus) occurred in large and deep lakes low in the landscape gradient, whereas the smaller species Ceriodaphnia dubia, Daphnia retrocurva and Leptodiaptomus minutus tended to occur high in the landscape. This shift in species composition was correlated with increased conductivity, primary productivity and the hypolimnetic refuges characteristic of larger deeper lakes lower in the landscape. Riparian housing development and littoral zone habitat (measured as building density and by abundance of logs in littoral zones) were not correlated with zooplankton community structure. In these relatively low-impact lakes, natural drivers are still the most significant determinants of zooplankton community structure.