1. Ensis americanus and Mya arenaria in the Wadden Sea
Coastal and Marine Ecosystem Field Studies, SS 2008
Fabian Delong, Sam Jantz, Rashed Sheriff, Jan Wildefeld

2. E. americanus Introduced to Europe in the late 1970’s
Rapidly spread along the continental coastline of the North Sea

3. Occupies the sediment in the sub-tidal and intertidal zones
Areas of colonization are scarcely populated with native fauna

4. M. arenaria
Present in Europe in late Pliocene
Possibly re-introduced to Europe in the 13th Century by Vikings

5. Wide range of habitat and food preferences
Highest densities found in intertidal and shallow sub-tidal zones

6. Methods
Sampled individuals of E. americanus along a 50 meter transect on the lower portion of the intertidal zone
50 individuals, 35 dead and 15 living
Measured length and counted growth ridges

7. Results

8. Results

9. Results

10. Impacts E.americanus No significant interactions with native species
Possibly hazardous for bathers. Occurs in fairly shallow depths
Can cause damage to trawls and other commercial fishing equipment

12. Impacts
M.arenaria
No information is available on impact since invasion of North Sea
No negative impacts on other species is observed today
Has been observed to competitively exclude native species in other regions

13. Management M.arenaria E.americanus
Has been thoroughly established for several centuries and seems to be benign. No action is needed
E.americanus
Seemingly benign, however population sizes as well as interactions with native species should be monitored

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