Effects of Anthropogenic Stressors on Crustacean Zooplankton in Lakes

Abstract

Crustacean zooplankton hold key roles in the pelagic food webs of lakes as they represent both important consumers of algae and prey for fish. Thus, stressors affecting both the bottom and top of the food web will cascade toward crustaceans, making them important indicators for anthropogenic stressors. This chapter focuses on three frequent stressors: changes in nutrient concentrations, climate warming, and neozoans. Stressor effects are mediated by the seasonality of stressor impact relative to other factors limiting zooplankton, and species traits, such as life cycle and anti-predator strategies of zooplankton. This chapter provides a background on seasonal dynamics and the diverse life cycle solutions and anti-predator strategies of zooplankton to exploit this seasonality. Using trait-based predictions, the responses of zooplankton to eutrophication and oligotrophication, warming, and invasive species are discussed with special focus on the crustacean community of Lake Constance. Results from other lakes will be used to analyze to which extent the responses of the Lake Constance crustaceans can be generalized. Changes in nutrient inflows can strongly change crustacean abundances in lakes and shift the relative importance of major groups. Warming has been shown to primarily shift the phenology of species, often without causing population declines or increases. Introductions or invasions of crustacean predators or competitors can change the dynamics of crustacean communities, often magnifying or reversing the effects of other stressors. The continuation of long-term studies will be crucial to improve our understanding of how the multitude of stressors and their interactions affect zooplankton dynamics and lake ecosystems.