Community structure of the macrobenthos of an important Belgian wintering area for the Common Scoter (Melanitta nigra)

The shallow western Belgian Coastbanks are important wintering areas for the Common Scoters, reflecting the ecological importance of this environment. The diet of these seaducks consists of macrobenthos, mainly bivalves. The availability of these bivalves along the Belgian west-coast has been poorly documented and it is not clear to what extent the spatial distribution of the Scoters and the bivalves are linked. In October 1994, 40 macrobenthic samples were taken in the area. Multivariate techniques revealed five communities, each characterized by sedimentological variables: (1) the Barnea candida community occurring in a very compact muddy sediment (median 14 µm), (2) the ‘Mytilus edulis’ community, with a rather coarse sediment (median 402 µm), (3) the Lanice conchilega community inhabiting a fine sandy sediment (median 211 µm), (4) the Nephtys cirrosa-Echinocardium cordatum community in a coarser fine sandy sediment (median 242 µm), and (5) the Nephtys cirrosa community also occurring in a slightly coarser fine sandy sediment (median 224 µm). Only the Lanice conchilega community, because of the high number of bivalve, possibly functions as feeding grounds for the Common Scoter. The spatial distribution of the bivalves in the Lanice conchilega community and the wintering Common Scoters will be compared.