Eider Canal Eider Canal The Eider Canal (also called the Schleswig-Holstein Canal) was an artificial waterway in southern Denmark (later northern Germany) which connected the North Sea with the Baltic Sea by way of the rivers Eider and Levensau. Constructed between 1777 and 1784, the Eider Canal was built to create a path for ships entering and exiting the Baltic that was shorter and less storm-prone than navigating around the Jutland peninsula. In the 1880s the canal was replaced by the enlarged Kiel Canal, which includes some of the Eider Canal's watercourse. The canal's watercourse followed the border between the duchies of
Baltic Sea as species in 2005 and 2018 respectively, having formerly been confused with more widespread relatives. The tiny Copenhagen cockle ("Parvicardium hauniense"), a rare mussel, is sometimes considered endemic, but has now been recorded in the Mediterranean. However, some consider non-Baltic records to be misidentifications of juvenile lagoon cockles ("Cerastoderma glaucum"). Several widespread marine species have distinctive subpopulations in the Baltic Sea adapted to the low salinity, such as the Baltic Sea forms of the Atlantic herring and lumpsucker, which are smaller than the widespread forms in the North Atlantic. A peculiar feature of the fauna is that it contains a