Intertidal macroalgal and epiphytic polychaete distributions strengthen marine ecoregions of Western Australia

The Marine Ecoregions of the World system separates oceans into 232 ecoregions based on coastal and shelfwater species distributions. We tested separation those delineated subecoregions within Western Australian waters using intertidal macroalgal epiphytic polychaete Environmental predictors assemblages were also determined. collected macroalgae polychaetes 38 rocky shores four marine from 18°S to 34°S: (1) Exmouth Broome, (2) Ningaloo, (3) Houtman, (4) Leeuwin. evaluated differences in composition among pairwise permutational multivariate analysis variance each ecoregion hierarchical cluster analysis. Multivariate relationships between environmental variables determined distance-based linear models. significantly differed ecoregions, with dissimilarity 78-96% for 62-75% polychaetes. identified three Broome Ningaloo two Houtman Leeuwin distribution. found no subecoregion could explain 51% total variation 41% top explaining a high proportion assemblage distribution sea surface temperature (15% 12% polychaetes) tidal amplitude (10% 6% polychaetes). These can be used as an alternative spatial framework classifying habitats designing protected area networks waters.