Effects of the mussel Mytilus edulis L. on the invertebrate fauna of sediments

Two field experiments were carried out to investigate the effects of mussels (Mytilus edulis) on fauna and on sediment characteristics. In the first experiment mussels were removed from within an established mussel bed to create bare patches and in the second experiment mussels were transplanted to an adjacent bare sandflat. In the mussel removal experiment, mobile epibenthic crustaceans (predominately Gammarus spp. and Jaera albifrons) were markedly reduced in bare patches whereas infaunal species were much less affected. In the mussel transplant experiment, mobile epibenthic crustaceans (e.g. Gammarus spp. and Jaera albifrons) colonised mussel transplant plots, but were absent at all times from the adjacent sandflat sediments. The polychaetes Eteone longa and Pygospio elegans were both significantly reduced in mussel transplant plots, whilst Capitella spp. increased in numbers. Mussels clearly had marked effects on both the fauna and sediments probably through a combination of biodeposition and filtration by the mussels and the provision of a structurally complex habitat. (C) 1999 Elsevier Science B.V: All rights reserved.