Spatial-temporal variations of a SW Atlantic macrobenthic community affected by a chronic anthropogenic disturbance.

The effect of the chronic anthropogenic disturbance in a coastal area of the SW-Atlantic was tested through a multimetric-approach. This study integrates environmental variables, biotic indices of environmental quality, and changes in alpha and beta diversity. The outfall site showed high percentages of organic matter, silt and clay in sediment and high concentration of Enterococcus in seawater. The invasive polychaete Boccardia proboscidea dominated the outfall site, while the ecosystem engineer Brachidontes rodriguezii dominated the non-impacted sites. Regarding partitioning of beta diversity the species loss (nestedness) at outfall site would be the process that drives the patterns found. Moreover, outfall site presented the lowest environmental health values in both spring and autumn. This community-level integrated analysis provides useful tools to consider when making decisions regarding coastal management.