The effect of climate on long-term changes in the crustacean zooplankton biomass of Lake Windermere, UK

Abstract

Fish predation is increasingly being viewed as one of the most important factors influencing the development of zooplankton populations in lakes^1–3. Marine zooplankton populations, on the other hand, are thought to be influenced primarily by the climate^4,5. We show here that year-to-year fluctuations in the biomass of crustacean zooplankton in Lake Windermere, in the United Kingdom, are strongly correlated with variations in water temperature, but poorly correlated with the abundance of the dominant plank-tivorous fish. This represents the first conclusive evidence of climatologically induced variability in a freshwater planktonic ecosystem. The links between climate and fisheries have recently been summarized by Cushing⁶, who suggests that climatic events regulate fish production through the matching or mismatching of their spawning with the period of available food. Our observations, reported here, suggest that year-to-year fluctuations in the biomass of crustacean zooplankton in Windermere are similarly influenced by the matching or mismatching of seasonal events in the zooplankton with the availability of algal food.