Freshwater.

Freshwater ecosystems in Germany, particularly lakes, host a variety of species that are vital to maintaining ecological balance. The European pike, a key predator, regulates fish populations, contributing to the overall health of these waters. However, the introduction of the American crayfish, an invasive neobiota, poses a serious threat to native species as it carries the deadly crayfish plague. This invasive species has spread rapidly, outcompeting and decimating native populations, highlighting the need for effective management and conservation of freshwater habitats to protect native biodiversity.