Invasion of the Wadden Sea by the Pacific Oyster (Magallana gigas): A Risk to Ecosystem Services?

Abstract

The Pacific oyster Magallana gigas (formerly Crassostrea gigas) was introduced in the Wadden Sea in the 1980s for aquaculture purposes. Soon after the introduction, oysters escaped from the commercial oyster farms and massively colonized the intertidal beds of the native blue mussel Mytilus edulis. A competitive suppression of the mussel population may have led to the loss of important ecosystem services provided by the mussels. Today, however, both species co-exist in dense mixed beds without substantial change in mussel density and functioning of the Wadden Sea ecosystem. The invasion of the Pacific oyster in the Wadden Sea provides an example of how relatively young ecosystems can integrate non-indigenous species without detrimental implications for ecosystem services.