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Changing interactions in the Wadden Sea

Fokkema, R.W. (2009) Changing interactions in the Wadden Sea. Bachelor's Thesis, Biology.

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The Wadden Sea is one of the largest intertidal ecosystems on earth. Situated along the coasts of the Netherlands, Germany and Denmark the area has shared a unique connection with early human development. Anthropogenic influences as exploitation and habitat change have started to affect ecological processes and species composition within the Wadden Sea from very early on. These effects especially intensified during the last half of the previous century. Resulting in the loss of many indigenous species of which several ecosystem engineers. Before 1900, four types of habitat could be distinguished in the Wadden Sea. The bare tidal flat and habitat provided by three ecosystem engineers. European flat oyster beds (Ostrea edulis), Seagrass beds consisting of Z. noltii and Z. marina and reefs built by colonies of the polychaete Sabellaria spinulosa. After the 1900s Oyster beds vanished from the Wadden Sea due to overexploitation. This was followed around the 1920s/1930s by the disappearance of most Sabellaria reefs and almost all Z. marina based seagrass beds. The oyster beds were taken over by the Blue mussel (Mytilus edulis) that from then on assumed the role as dominant ecosystem engineer. Species associated with mussel beds increased in abundance. History repeated itself around the 1990s when an increase in mussel fishery resulted in a dramatic decrease in the area of stable littoral mussel beds. Restrictions to mussel fishery have not yet resulted in the recovery of stable littoral mussel beds. To determine the causes for this lack of recovery and to find a way to successfully aid in the restoration of mussel beds a large scale project is to be conducted in the Dutch part of the Wadden Sea. The restoration of mussel beds is expected to aid in bringing the whole ecosystem back to a more ‘natural’ ecological state. The future of the Wadden Sea area might however not be so bright. It might prove impossible to get the ecosystem in a stable state associated with high biodiversity under the strain of upcoming changes caused by factors like climate change and invading species. One of these invading species the Pacific oyster (Crassostrea gigas) is likely to become a dominant ecosystem engineer in the Wadden Sea and might outcompete the Blue mussel (Mytilus edulis).

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 07:28
Last Modified: 15 Feb 2018 07:28

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