Artificial reef impact on macrobenthic community on south-eastern Brazil coast

Abstract

Spatial variations on the macrobenthic composition and structure associated with artificial reefs (ARs) on the south-eastern Brazil coast were related to particle size and geochemical characteristics of the sediment and to bottom currents velocity in the vicinity of ARs and two control areas (CAs). The sampling periods were related to Paraiba do Sul River (PSR) flow, highest in summer months. The sediment was more heterogeneous near the ARs, composed mainly of mud and gravel and with greater abundance of shellfish compared to the CAs predominated by mud. The influence of the artificial structures on the hydrodynamics of the site was evident with significantly lower current velocity. Macrobenthos richness, abundance and diversity varied spatially, with higher mean values near the ARs in both sampling periods, reinforcing the influence of artificial structures on the associated infauna. Significant temporal differences in the concentrations of phosphorus, nitrogen and dissolved organic carbon only on the CAs suggest that the effect of the artificial structures surpasses the environmental seasonality related to the PSR flow. The artificial modules created a more heterogeneous grain size of the sediment that contributed to the enrichment of associated macrobenthos, with higher species richness and abundance due to a higher niche availability.