Faunal structures associated with patches of mussels on East Asian coasts

Abstract.

Aggregations of mussels harbor a variety of associated animals and make it possible for diverse species to coexist at the shore. Species composition and diversity of the associated fauna are controlled by the position of mussel beds or patches, e.g. tidal level, age structure of mussels, quality of ambient water and by mussel species. When patches of mussels were surrounded by algal growth, a difference in the species composition of the associated fauna was recognized between the patches and algal mats. Mechanisms promoting coexistence are discussed. Biodeposit production by mussels may affect the environment both within the bed and the ambient waters. Reducing sediments showing low Eh values caused by the accumulation of biodeposits was observed in calm waters where the polychaete Capitella capitata, an indicator for organic enrichment, occurred both in the intertidal mussel bed and the subtidal sandy bottom communities. In a shallow subtidal sandy bottom of the Gulf of Thailand, where heavy bioturbation by the spatangoid urchin Brissus latecarinatus was occurring, small patches of the mussel Modiolus metcalfi increased species diversity and equitability in this habitat. Species composition was different between mussel patches and pure sandy bottoms.