FRESHWATER ZOOPLANKTON COMMUNITIES AS INDICATORS OF HABITAT QUALITY: TESTING RESPONSES TO MULTIPLE DISTURBANCES

Zooplankton can be effective bioindicators of water quality because they are common to most aquatic ecosystems, can be rapidly sampled, and different zooplankton taxa respond differentially to environmental change. During the summers of 2014 and 2015, 106 samples were collected from 53 ponds in the San Francisco Bay Area to evaluate how zooplankton communities respond to disturbances in their environments, such as eutrophication and presence of non-native fishes. We found that zooplankton communities were sensitive to greater nutrient concentrations, such as phosphorus, which had a negative effect on zooplankton species richness and the density of certain zooplankton taxa, notably, cladocerans such as Simeocephalus vetulus and S. serrulatus. The presence of non-native fish had a strong, negative effect on zooplankton density and average body size, but did not affect species richness. We found that ponds with a greater degree of turbidity had lower cladoceran species densities, but had slightly higher densities of copepod taxa. Overall, these results suggest that common forms of environmental alteration, such as invasive species and nutrient runoff, have differential impacts on zooplankton species riches, average body size, and species density, highlighting their potential value as bioindicators within pond ecosystems