Pocillopora damicornis-associated echinoderm fauna: richness and community structure across the southern Mexican Pacific

The reef-associated echinoderm cryptofauna has received scarce attention notwithstanding its large-scale effects on reef community structures and ecosystem functioning world-wide. In the present study, a spatially hierarchical quantitative sampling protocol was designed to address Pocillopora damicornis-associated echinoderm diversity within and across southern Mexican Pacific reef localities. It was also aimed to evaluate if species composition and abundance varies across several spatial scales. The number of sampled echinoderm species from 36 P. damicornis coral heads was 24, which fell inside the 95 % confidence interval of the Chao1 species richness estimator, while as many as 42 species were expected to occur. The analysis indicated that the echinoderm diversity was not particularly large among the samples (4–6 species) or across localities (5–12 species). Nevertheless, the observed associated echinoderm richness resulted from a small, although significant, species replacement among the coral heads and reef localities across the southern Mexican Pacific. The relative large number of echinoderms associated with P. damicornis may serve as a proxy for predicting potential biodiversity loss caused by the coral reef degradation currently observed in the study area.