Rapid assessment of invertebrate biodiversity on rocky shores: where there's a whelk there's a way

The lack of species inventory data for most marine habitats currently hampers the objective management of marine biodiversity. There is thus a clear need to find reliable indicator taxa that can be targeted in marine conservation studies, providing cost-effective data for planning and monitoring. Using the rocky shores of the Solitary Islands Marine Park, NSW, Australia, as a model, I evaluated macroinvertebrates and determined which taxa (i) best reflected ecological patterns of the broader intertidal community; and (ii) were able to accurately predict species richness of assemblages at the headland scale. Both molluscs and crustaceans showed high levels of correlation with overall species richness. However, molluscs, and in particular prosobranchs, most closely reflected patterns in the community data and provided the most accurate predictions of species richness at the scale of the headland. The potential time savings of using molluscs in rapid assessments are considerable and relate to reductions in field time (by up to 40%) as well as the reduced need to invest time developing extensive taxonomic knowledge of other invertebrate groups. Molluscs are widespread and easily sampled, with stable taxonomy and well-known ecology relative to other marine invertebrate taxa. Their use as surrogates of biodiversity shows great potential for future marine conservation studies.