Hur kommer den vanliga sjöstjärnan (Asterias rubens) att påverkas av invasionen av japanska jätteostron (Crassostrea gigas)?

The dispersal of invasive species is a global problem. One of the most recent invasive species on the Swedish west coast is the pacific oyster (Crassostrea gigas), which was firstly discovered in 2007.

This invasion might lead to tremendous effects on other species. Therefore we examined how the native species –the starfish (Asterias rubens) will be effected by the invasion and settlement of the pacific oyster due to its impact on the starfish’most common food–the native blue mussel (Mytilus edulis). We studied whether it is possible for the common starfish to feed upon pacific oysters. A starfish was placed in a tank with a pacific oyster where the starfish made an attempt to open the oyster but did not fulfil the attack. Furthermore we examined if the starfish had a preference for either the essence from oysters or their natural food, the blue mussel. The starfish showed a preference for oysters in 11 out of 15 times which trough statistical methods lead to a p-value of 0,07. From this we concluded that there is a possibility that somestarfish might be able to feed on pacific oysters, which would help keep the oyster population under control. We also speculate how starfish as a specie will survive and adapt to the newly settled pacific oyster

Björn Bergwall, Sonja Edström och Yonathan Habte



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15 september, 2016