For a long time it has been known that a fresh water supply through rain, groundwater leaks and over rivers can be an important source of nutrients into the sea. These invisible nutrient as well as pollutant inputs affect marine communities and can, for example, cause toxic algal blooms. For the North Sea, mainly the German tributaries Elbe, Ems, Weser and Eider have been researched. Submarine - submerged - fresh water sources, such as those found on the East Frisian Islands, are so far little explored, although they have a similar nutrient influence as the aboveground inflows. (Blog is written in German)

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