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HAVKYST-Havet og kysten

ALIEN OYSTER - distribution, population development and effects of the invasive Pacific oyster (Crassostrea gigas) in the Skagerrak

Awarded: NOK 2.3 mill.

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Introductions of alien species been recognized globally as a major threat to biological diversity. The invasive Pacific oyster (Crassostrea gigas) was introduced for aquaculture purposes to Europe from Japan during the 1960s to replace overexploited stock s of European oysters (Ostrea edulis). Low water temperatures were believed to restrict reproduction and establishment of wild populations. However, wild populations were established, for example in the Wadden Sea, and massive spreading of Pacific oyster took place during warm summers in the beginning of the 2000s. In 2006, mass settlement of the Pacific oyster was observed in Sweden and in the following years this was also observed in Norway. The Pacific oyster is a habitat-modifying species that has b een shown to have a large impact on the environment by turning soft bottoms into hard reef structures. Although there are a variety of studies that have addressed the impacts of Pacific oyster on benthic environments, only a few studies have assessed the effects on biodiversity, and to our knowledge no study have used models to predict the future distribution pattern of this species. In this study, we will 1) map the present distribution and model the likely future distribution of Pacific oyster in the Os lofjord 2) assess the population structure, mortality, recruitment and population development of the Pacific oyster 3) study the effects of Pacific oyster on blue mussel beds and associated diversity of native fauna and flora 4) identify the origin and in troduction pathway of the Pacific oyster through genetic studies. This project will provide knowledge of introduction routes, establishment, population development of Pacific oyster and its effects on native fauna and flora that will help natural resourc e managers to develop monitoring and action plans for this invasive species.

Funding scheme:

HAVKYST-Havet og kysten