Macrobenthic assemblage structure in a cool-temperate intertidal dwarf-eelgrass bed in comparison to those in lower latitudes.

The evolution and ecology of latitudinal patterns in marine macrofaunal biodiversity and assemblage structure are contentious. With the aim of investigating the occurrence of such patterns in intertidal dwarf-eelgrass beds (Nanozostera spp.), those at cool-temperate Scolt Head Island, UK (latitude 52°N), were examined and compared to equivalent systems in warm-temperate Knysna, South Africa (34°S), and subtropical Moreton Bay, Australia (27°S); systems that had earlier been examined using identical methodology. The Scolt Head bed supported the highest faunal density (mean 6,568 0.1m-2), lowest observed and estimated species richness (32 and 33 spp respectively), lowest species diversity (Simpson’s Index 0.34), highest mean Constancy Index (23.0), lowest proportion of total numbers contributed by singletons or doubletons (0.06%), largest Berger-Parker Dominance (0.81), and least degree of variability between component samples. The beds at Knysna were intermediate between those at Scolt H...