Fauna of Europe of the Baltic Sea has led to the evolution of many slightly divergent species, such as the Baltic Sea herring, which is a smaller variant of the Atlantic herring. The most frequent benthic species are "Saduria entomon" and "Monoporeia affinis", which is originally a freshwater species. A great part of its bottom is anoxic and without animal life. The Baltic Sea and North Sea are also home to a variety of marine mammals (common seals, grey seals). Europe contains several important freshwater ecoregions, including the heavily developed rivers of Europe, the rivers of Russia, which flow into the Arctic, Baltic,
Wadden Sea Agreement Wadden Sea Agreement The Agreement on the Conservation of Seals in the Wadden Sea is an agreement between Wadden Sea countries, aimed at protection of seals and concluded in the aegis of Convention on Migratory Species (CMS) in 1990. Common seals, or harbor seals, are nearly threatened true seal species, inhabiting temperate and Arctic marine coastlines of the Northern hemisphere. They are found in coastal waters of the northern Atlantic and Pacific Oceans as well as those of the Baltic and North Seas. Harbor seals are brown, tan, or gray, with distinctive V-shaped nostrils. An adult can attain a length