Spatial variability of macrofaunal traits across the Greater North Sea

Abstract

Large-scale spatial variability of macrofaunal traits has rarely been studied. This paucity of information hinders progress to derive indicators of seabed integrity under current policy drivers. Based on data from 327 stations across the Greater North Sea, a sub-region of the EU Marine Strategy Framework Directive (MSFD), we describe variability in the numerical dominance of ten important macrofaunal traits and their relationships with the physical environment.For six traits (longevity, larval development position, egg development position, sediment position and bioturbation method), macrofaunal assemblages were dominated by one or two trait categories; these traits showed more pronounced spatial patterns than traits with a wider (and more even) trait category expression. Similar spatial distributions of some dominant categories were observed. For example, egg-brooding, surface-dwelling and suspension feeding traits were dominant in the central English Channel and off the Humber Estuary. Traits generally showed weak spatial relationships with environmental variables, although sediment position and feeding type were related to variations in bed shear stress and gravel content. We discuss the implications of these findings in relation to monitoring seabed integrity under the MSFD.