The impact of invasive eastern mosquitofish (Gambusia holbrooki Girard, 1859) on zooplankton in small Mediterranean ponds.
Mediterranean ponds are reservoirs of biodiversity for aquatic invertebrates and today they are often exposed to negative anthropogenic influences. Zooplankton is significant part of invertebrate biodiversity in theses habitats, and is considered as relevant indicator of the pond ecological status. The composition, density and biomass of zooplankton in the investigated ponds were most influenced by biotic factors: the biomass of phytoplankton, macrophyte coverage and fish. Phytoplankton and macrophytes positively affected zooplankton, while the presence of fish (invasive eastern mosquitofish) had negative affect on zooplankton assemblage. Zooplankton did not respond equally to mosquitofish - Cladocera and Copepoda were the most vulnerable groups and their populations were almost completely eliminated in ponds with mosquitofish, whilst Rotifera were less susceptible. Overall, invasive species i.e. mosquitofish, may cause deterioration in biocoenosis and ecosystem as well.