An analysis of mussel bed habitats in the Dutch Wadden Sea

A habitat suitability analysis for littoral mussel beds in the Dutch Wadden Sea was carried out. The analysis was based on the presence of mussel beds in the years 1960-1970, and a number of environmental characteristics: wave action, flow velocity, median grain size, emersion times and distance to a gully border. The habitat model describes mussel bed appearance quantitatively. It predicts the distribution of mussel beds quite well, as well as the distribution of spatfall in the years 1994 and 1996. From the analysis we found that wave action (maximum orbital velocity) was the main structuring factor. A low orbital velocity was preferred. Neither very low, nor maximum flow velocities were favourable for mussel beds. Very coarse sands or silty environments were not preferred. Sites close to the low water line showed lower mussel bed appearance; when emersion time was above 50%, hardly any mussel beds could be found. The habitat suitability analysis and the construction of a habitat suitability map was performed in the framework of the discussions on a further or reduced exploitation of the tidal flats in the Dutch Wadden Sea by cockle and mussel fishery activities.