Report: Heart shell population Emsmündung (1980-1981)
Description
The study was based on extremely large quantities of clams (approx. 3 000 m³), which were washed up in 1980 and 1981 on the western head of the island of Borkum.
The study included an inventory of the cockpit populations in the estuary by population density, biomass, ageing and differentiation in site forms (Cerastoderma edule, Cerastoderma lamarcki, Cerastoderma glaucum); furthermore, the occurrence of clams with malformed shells and, on selected samples, infestation with parasites and exposure to heavy metals and chlorinated hydrocarbons. The sampling was carried out from April to September 1981 at 142 stations.
As a result, it turned out that the mudflats of the Ems estuary could not be considered as the area of origin of the flushed material and that most of the initially suspected causes could be excluded. The occurrence of mass flushing is most likely to be explained as a natural process.
Result: The animals of the washed-up material do not come from the mudflats of the Ems estuary, but all indications indicate that they were delivered by a bank lying seaward from Borkum.
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Tags
- cerastoderma-edule-cerastoderma-lamarcki-cerastoderma-glaucum-schwermetalle-massenanspülung-nlwkn-chlorierte-kohlenwasserstoffe
- westerems-borkum-osterems-randzel-emsmündung