Invertebrate communities associated with blue mussel beds in a patchy environment: A landscape ecology approach

Abstract

Landscape ecology has evolved rapidly as a terrestrial discipline over the past centuries due to an increased concern over habitat loss and fragmentation. Proceedings in the marine realm have been comparatively scarce, even though many key habitats in marine ecosystems are becoming equally fragmented. We sampled the macrofauna associated with blue mussel beds in naturally patchy landscapes of islands and reefs in the non-tidal Baltic Sea and tested for the effect of island area, isolation and reef depth on local species richness and composition. The fauna was also compared among islands and reefs. Contrary to expectations, species richness did not increase with island size, and species diversity was higher on deep reefs compared to shallow reefs and islands protruding from the water. Region and depth also had an effect on species assemblage. Geographical distance to nearest island or reef showed no correlation with species richness but correlated positively with faunal density, i.e. a higher degree of isolation increased density. In accordance with other marine studies, our data, therefore, supports the nearest refuge hypothesis, postulating that mobile invertebrates disperse over areas of non-habitat and then concentrate in isolated habitats because habitats in isolation are the nearest available refuge. We show that terrestrial landscape approaches cannot be directly applied to the study system. This has important implications for the planning of marine protected areas and their management. © Inter-Research 2012.