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What will happen to birds when Pacific Oysters take over the mussel beds in the Wadden Sea?
Scheiffarth, G.; Ens, B.; Schmidt, A. (2007). What will happen to birds when Pacific Oysters take over the mussel beds in the Wadden Sea? WSN 1: 10-14
In: Wadden Sea Newsletter. Research Institute for Nature Management: Wilhelmshaven. ISSN 0922-7989, more

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    Feeding; Foraging habitats; Introduced species; Marine birds; Oyster beds; Oysters; Carcinus maenas (Linnaeus, 1758) [WoRMS]; Crassostrea gigas (Thunberg, 1793) [WoRMS]; Larus argentatus Pontoppidan, 1763 [WoRMS]; Numenius arquata (Linnaeus, 1758) [WoRMS]; ANE, Wadden Sea [Marine Regions]; Marine

Authors  Top 
  • Scheiffarth, G.
  • Ens, B.
  • Schmidt, A.

    Since the beginning of the 21st century the introduced Pacific Oyster (Crassostrea gigas) has increased significantly in the Wadden Sea. One of the preferred settling structures for oyster larvae are existing mussel beds, resulting in a conversion of a large fraction of mussel beds into oyster beds. As mussel beds are one of the preferred foraging habitats for birds, this has led to the concern that birds might lose feeding opportunities in the Wadden Sea. However, the available data suggest that for birds feeding on the associated fauna (i.e. Curlews (Numenius arquata) feeding on shorecrabs (Carcinus maenas) no difference in habitat quality is to be expected. For birds feeding on mussels, the conversion of mussel beds to oyster beds is probably negative, but reactions are species specific. Herring Gulls (Larus argentatus) feed on shore crabs on old mussel beds, but swallow small mussels whole on young mussel beds. However, contrary to mussels, even small oysters cannot be detached from the substrate. Oystercatchers (Haematopus ostralegus) can feed on oysters, as indicated by studies elsewhere in the world, but profitability of this new food source has still to be determined. At present, feeding densities on oyster beds are lower than feeding densities on mussel beds. Common Eiders (Somateria mollissima) are most probably not capable of feeding on oysters, so that this species might suffer most from the change in the foraging habitat.

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