The meltdown of biogeographical peculiarities of the Baltic Sea: The interaction of natural and man-made processes

The biogeographical peculiarities of the Baltic Sea have developed since th e last glacial period. The characteristic mixture of marine, brackish water , and freshwater species, and relicts from previous periods in the Baltic, is threatened by ongoing environmental changes. This review focuses on the recent impacts of nonindigenous species, eutrophication, and a temporary ox ygen deficit in the deep basins, on the biogeographical integrity of the Ba ltic on different spatial and time scales. Today the biota of brackish wate rbodies are exposed to each other because of the breakdown in geographical barriers due to shipping traffic, leading to an exchange of species and fur ther homogenization of aquatic animal and plant life worldwide.