Tree of the sea:The use of the internal growth lines in the shell of Arctica islandica (Bivalvia, Mollusca) for the retrospective assessment of marine environmental change

摘要

Within the North Sea the southernmost distribution limit of Arctica follows the 30 m depth contour. This border is most likely set by the maximum bottom water temperature of 16 graden. Densities of 16 individuals/m2 were found in the northern North Sea. In the south-eastern North Sea the maximum density of 0.1 ind./m2 is low, especially compared to those around Iceland or the western Atlantic. In the south-eastern North Sea the densities decreased between the 1970s and the early 1990s. Both the percentage of sampling stations and the corresponding densities decreased. The mortality rate in the south-eastern North Sea is twice as high as that in the northern North Sea. ... Zie: Summary