Consequences of antimicrobials and antiparasitics administration in fish farming for aquatic ecosystems

Aquaculture is an important source for food, nutrition, income and livelihoods for millions of people around the globe. Intensive fish farming is often associated with pathogen outbreaks and therefore high amounts of veterinary drugs are used worldwide. As in many other environments, mostly application of antimicrobials triggers the development of (multi)resistant microbiota. This process might be fostered by co-selection as a consequence of the additional use of antiparasitics. Usage of antimicrobials in aquaculture does not only affect the cultured fish species, but - to a so far unknown extent - also aquatic ecosystems connected to fish farms including microbiota from water and sediment as well as its eukaryotes. Effects include increases in the number of (multi)resistant microbes, as well as complete shifts in microbial community structure and function. This dysbiosis might have pronounced consequences for the functioning of aquatic ecosystems. Thus in the frame of this project we want to study consequences of antimicrobial/-parastic application in aquaculture for the cultured fish species as well as for the aquatic environments. To consider the variability of aquaculture practices worldwide four showcases representing typical systems from the tropics, the Mediterranean and the temperate zone will be studied including freshwater and marine environments. For one showcase a targeted mitigation approach to reduce the impact on aquatic ecosystems will be tested.