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

Functional diversity in the intertidal macrobenthic community at sewage-affected shores from Southwestern Atlantic

Sewage pollution effect in a coastal area of the Southwestern Atlantic was tested, through the use of analysis of biological traits (BTA) and functional indices. Changes in the macrobenthic functional structure between the sewage outfall site and remote sites were observed. At the site in the discharge point, functional features related to organic enrichment were observed, such as deposit feeders, burrow dwellers and inhabitants of tubes, with low relative mobility and opportunistic species of the first and the second order. The functional indexes (Evenness, Dispersion, and Functional Specialization) showed the highest values in the sites far from the discharge point. The AMBI was positively correlated with FRic and negatively with FEve and FSpe. The opposite occurred with the M-AMBI. BTA and functional indices showed the changes that occurred due to sewage impacts in the benthic assemblages on rocky coasts in SW Atlantic. Sewage pollution effect in a coastal area of the Southwestern Atlantic was tested, through the use of functional diversity metrics (analysis of biological traits and functional indices). Biological samples were taken during spring and autumn (2015-2016), in four sampling sites distributed at different distances from the sewage outfall. Changes in the macrobenthic functional structure between the sewage outfall site and remote sites were observed. The functional indexes (Evenness, Dispersion, and Functional Specialization) showed the highest values in the sites far from the discharge point. Correlations between functional and environmental quality indices (AMBI and M-AMBI) were significant. The AMBI was positively correlated with Functional Richness and negatively with Functional Evenness and Functional Specialization. The opposite occurred with the M-AMBI. The analysis of biological traits and functional diversity indices represent informative and useful tools to describe the different aspects of sewage impacts in the benthic assemblages on rocky coasts in SW Atlantic. At the site in the discharge point, functional features related to organic enrichment were observed, such as deposit feeders, burrow dwellers and inhabitants of tubes, with low relative mobility and opportunistic species of the first and the second order.

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.

Assessment of seawater quality and bacteriological pollution of rocky shores in the central coast of San Jorge Gulf (Patagonia, Argentina)

We assessed seasonal and spatial variability of seawater quality and bacterial pollution in two sewage-impacted and two reference rocky shores in the area of Comodoro Rivadavia, the largest city in central Patagonia. Samples taken from winter 2015 to autumn 2017 at different intertidal levels showed that the impacted sites experienced a decrease of salinity-more pronounced towards the autumn-, a slightly higher turbidity, the lowest values of dissolved oxygen, and significantly higher concentrations of nitrates throughout the year. They also were up to ten times above the legal limit of fecal indicator bacteria (FIB) for recreation and fishing areas. Enterococci increased particularly during winter. All bacteriological indicators decreased markedly during spring. Principal component analysis arranged the reference sites mostly by their higher salinity, and the impacted sites by concentration of FIB, nitrates and phosphates. Impacted and reference sites overlapped towards lower levels, where the explicative variables were more stable.

Role of Reef-Building, Ecosystem Engineering Polychaetes in Shallow Water Ecosystems

Although the effect of ecosystem engineers in structuring communities is common in several systems, it is seldom as evident as in shallow marine soft-bottoms. These systems lack abiotic three-dimensional structures but host biogenic structures that play critical roles in controlling abiotic conditions and resources. Here I review how reef-building polychaetes (RBP) engineer their environment and affect habitat quality, thus regulating community structure, ecosystem functioning, and the provision of ecosystem services in shallow waters. The analysis focuses on different engineering mechanisms, such as hard substrate production, effects on hydrodynamics, and sediment transport, and impacts mediated by filter feeding and biodeposition. Finally, I deal with landscape-level topographic alteration by RBP. In conclusion, RBP have positive impacts on diversity and abundance of many species mediated by the structure of the reef. Additionally, by feeding on phytoplankton and decreasing water turbidity, RBP can control primary production, increase light penetration, and might alleviate the effects of eutrophication affecting supporting ecosystem services, such as nutrient cycling. They can also modulate cultural ecosystem services by affecting recreational activities (e.g., negative impacts on boating and angling, increased value of sites as birdwatching sites). Acknowledging the multiplicity of synergistic and antagonistic effects of RBP on ecosystems and linking changes in habitat structure, filter-feeding activities, and biodeposition to ecosystem services are essential for effective decision-making regarding their management and restoration.