Use of Zooplankton Size to Assess the Community Structure of Fish Populations in Freshwater Lakes

In this study, we examined the relationship between mean size of zooplankton and fish community structure in 35 New York lakes. The study lakes contained fish populations dominated by percids, centrarchids, or both, and were categorized based on fish species composition and the ratio of predators to panfish. An increase in the predator-to-panfish ratio was matched by an increase in zooplankton size, indicating that zooplankton size represents a suitable index of predator-prey balance. Mean zooplankton size also decreased as the abundance of age-0 fish increased and increased when the predator: panfish ratio increased after a successful introduction of piscivores. To assess fish community structure from mean size of crustacean zooplankton, we recommend that sampling for zooplankton be done once in the spring and once in midsummer.