Contribution of freshwater metazooplankton to aquatic ecosystem services: an overview

Although its role in the functioning of aquatic systems is widely recognized, the contribution of freshwater metazooplankton (metazoan plankton) to ecosystem services (ES) is seldom considered. Here we aim at providing a first overview of how this group contributes to ecosystem services according to the Millennium Ecosystem Assessment framework. We show that although metazooplankton hardly generates any provisioning services, it provides crucial support to the generation of other services. Metazooplankton is important for fisheries because it forms an essential food item for the larval and juvenile stages of most freshwater fish and acts as a trophic link between phytoplankton and microbial communities and the fish community. Through its stoichiometric homeostasis and ability to feed on biochemically complementary food sources it may also act as a buffer against bottom-up effects of nutrient deficiencies in primary producers. Metazooplankton often has a crucial regulatory function by controlling phytoplankton growth and dissolved organic carbon, contributing to the quality of drinking and irrigation water supplies and of the underwater light climate. It provides attractive study material for didactic purposes and some taxa have served as model systems that have considerably aided progress in scientific disciplines, such as ecology, evolutionary biology, ecotoxicology, environmental, and biomedical sciences.