Anthropogenic Impacts on Coral Reef Harpacticoid Copepods

The number of studies demonstrating the susceptibility of benthic reef communities to anthropogenic impacts is growing. However, for some of the components of reef fauna, such as meiobenthic harpacticoid copepods, information is still lacking. Here, different diversity and taxonomic distinctness indexes and multivariate analyses were used to test whether the assemblage of harpacticoid copepods colonizing Artificial Substrate Units (ASUs) is an appropriate tool for the identification of reefs subjected to different levels of anthropogenic pressure. Furthermore, we also evaluate if diffused, persistent, anthropogenic impacts generate the homogenization and simplification of Harpacticoida assemblages. Six reefs were organized into two groups along the coast, depending on their proximity to very large urban centers. ASUs were used for meiofauna colonization and, for each reef, 320 Harpacticoida individuals were separated for identification at the species level. Abiotic parameters were analyzed, and significant differences were found between the two groups of reefs, with an increase in dissolved inorganic nutrients found in areas near large urban centers. Both the multivariate analyses and the indexes of diversity showed a clear separation between the reefs closer to the urban zones and those further away, as a response to the anthropogenic pressure. As hypothesized, in the impacted reef areas, there was a strong simplification and homogenization of the harpacticoid copepod assemblages. However, the results of the indexes, based on taxonomic distinctness, suggest that there was no phylogenetic signal of anthropogenic impact on coral reef harpacticoid copepods.