De verspreiding van Ensis directus (Conrad, 1843) in Noord-Frankrijk
Severijns, N.; Vanhaelen, M.-Th. (1994). De verspreiding van Ensis directus (Conrad, 1843) in Noord-Frankrijk. De Strandvlo 14(3): 84-91
In: De Strandvlo: Driemaandelijks Tijdschrift van De Strandwerkgroep België. De Strandwerkgroep België: Ursel. ISSN 0773-3542, more
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| Authors | | Top |
- Severijns, N., more
- Vanhaelen, M.-Th.
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| Abstract |
The distribution of Ensis directus in the north of France was studied. After the first reports of Ensis directus on the beach of Bray-Dunes in January and February 1988 (KERCKHOF & DUMOULIN, 1988a), it bas moved very fast to the south. At present the species is very common between the Belgian-French border and Calais. It seems to be absent however between Sangatte and Bou1ogne-sur-Mer, as apparently also the other Ensis species as well as Solen marginatus ! It is not yet clear why Ensis directus would not live in the sandy environment of the beaches of Wissant and Wimereux. Collections on beaches south of Boulogne-sur-Mer show no evidence that the conclusion of an earlier report (SEVERIJNS & GILLES, 1993), namely that Berck-Plage is very probably the most southern European location where Ensis directus lives at this moment, does not have to be changed. Finally, the dataset seems to suggest that Ensis directus moves southward much faster when the coastline is directed north-south than when it is directed east-west. The reason for this is not yet clear .It might e.g. be related to the directions of the ocean currents. It is further probably that the rocky region around the Cap Griz-Nez has slowed down the spreading of Ensis directus to the south as well. |
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