The intertidal zoning of cockles (Cerastoderma edule) in the Wadden Sea, or why cockle fishery disturbed areas of relatively high biodiversity

Abstract

Recently, Kraan et al. (ICES J Mar Sci 64:1735-1742, 2007) reported that areas in the Wadden Sea selected by mechanical cockle dredgers were of greater zoobenthic diversity than areas that remained undredged. The present paper attempts to explain this observation, focussing on the elevation-related zoning of the macrobenthic fauna on tidal Xats. Dense beds of cockles Cerastoderma edule occur in a speciWc intermediate intertidal-height zone where more species are present (and reach their maximal abundance) than in either lower or higher zones. This coincidence of preferred intertidal zones in many species, including cockles, may cause the higher species richness (and higher total macrozoobenthic biomass) of the Wsherchosen dredging areas as compared to other nearby nondredged tidal-Xat areas. © Springer-Verlag and AWI 2009.