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.

Rapid sewage pollution assessment by means of the coverage of epilithic taxa in a coastal area in the SW Atlantic.

The sewage pollution impact over coastal environment represents one of the main reasons explaining the deterioration of marine coastal ecosystems around the globe. This paper aims to detect promptly a putative sewage pollution impact in a Southwestern Atlantic coastal area of Argentina as well as to identify a straightforward way for monitoring, based on the relative abundance coverage of the intertidal epilithic taxa. Four sampling sites were distributed at increased distances from the sewage outfall where the cover of individual epilithic species was visually estimated. The surrounded outfall area (i.e. outfall site) resulted polluted with high percentages of organic matter in sediment and Enterococcus concentration in seawater. The structure of the community showed a remarkable difference between the polluted site (outfall site) and the unpolluted sites. The polychaete Boccardia proboscidea dominated the outfall site with variable abundances of the green algae Ulva sp. during the period of study, decreasing the diversity of the community, while the mussel Brachidontes rodriguezii and variable abundances of several algae species dominated the unpolluted sites. The monitoring of the benthic community represents an effective, non-destructive, relative inexpensive and rapid method to assess the health of the coastal environment in the study area. The large abundance of B. proboscidea along with the absence of B. rodriguezii individuals at <300m to the sewage outfall discharge allowed the success of this classical monitoring method in a temperate marine-coastal ecosystem with certain gradient of pollution.