Two estuary and two coastal lagoon stations along Chennai, Southeast coast of India were monitored for 1year to study both physicochemical and microbiological properties of the water. Influence of the marine environment over the systems was evident by elevated salinity levels. Considerable concentrations of total heterotrophic bacterial count and fecal bacteria such as total coliforms, fecal coliforms and fecal streptococci were observed throughout the study period which evinced a pattern of anthropogenic activities. Principle component analysis was employed for assessing the overall pattern of variation within the data sets. Climatic variation was highly correlated with changes in water quality, i.e. the Northeast monsoon and Summer had influenced considerably the microbial occurrence as well as the physicochemical parameters such as total suspended solids, chloride, sulphate and salinity. However, the effect of the Southwest monsoon was less prominent than the Northeast monsoon with its heavy rains. As both estuaries revealed elevated concentrations of polluted water, these stations can be used as indicators or alerts for the water quality along the coastal zone of Chennai.

The first phase of the Taparura Project aimed at restoring the north coast of Sfax (Tunisia), highly polluted by phosphate industry and uncontrolled phosphogypsum dumping. Before restoration of the north coast of Sfax, we investigated the state of the ecosystem in related coastal waters. To establish the impact of the Taparura Project, we conducted a similar study both after restoration. To discriminate natural changes over time, we extended the study to the south coast of Sfax, submitted to the same industrial pressure but not yet restored. The present study, conducted in May 2010 at 36 stations (18 on each coast, north and south), covered the spatial distribution of the microbial assemblage, nutrients, and abiotic parameters by collecting seawater samples at the surface and the water–sediment interface. Results revealed a striking difference between the two coasts regarding pH, with strong acidification of seawater in the south, likely generated by industrial activity. Suspended matter was higher in the north than in the south. Flow cytometry analysis of ultraphytoplankton (<10μm) resolved six groups (Prochlorococcus, Synechococcus, nanoeukaryotes and three distinct subgroups within picoeukaryotes). In addition to these autotrophic groups, two unknown groups were characterised on the south coast. Heterotrophic prokaryotes were resolved into three groups, labelled LNA (low nucleic acid content), HNA1 and HNA2 (high nucleic acid content). Prochloroccocus, pico-nano-microphytoplankton, heterotrophic prokaryotes and ciliates were more abundant in the north, whereas Synechococcus and unknown species were more abundant in the south where chl a concentration was also higher. The results show that restoration had positive effects on the microbial assemblage of the north coast; they also highlight the strong acidification still prevalent in the south that may be responsible for the lower development of most phytoplankton groups and the occurrence of unknown species. The case for restoration of the city’s south coast is also reinforced.

Samples of the polychaete Chaetopterus variopedatus, worm tubes, commensal crab Polyonyx gibbesi and sediments were collected in eight sites in Todos os Santos Bay, Brazil, in order to evaluate the potential use of the polychaetes and crabs as biomonitors and to assess the relationships and accumulation of trace and major elements in different benthic compartments. Trace and major elements were determined by ICP OES. Organic carbon, total nitrogen and sulfur were determined by CNS elemental analyser. Tubes, crabs and polychaetes were important in the retention of trace and major elements. Metals that presented the highest accumulation in polychaetes (i.e. Mg>Al>Fe>Zn>Mn>Co>Cu>Ba>Cr) where the same for crabs (i.e. Mg>Al>Fe>Mn>Co>Zn>Cu>Ba>Cr). High concentrations of Al, Ba, Cr, Mn and Fe, from terrigenous sources, were observed in tubes, which presented accumulation factors up to 81.5 for Mn. Sedentary polychaetes are seen as good biomonitor alternatives for metal contamination studies, because they are one of the most abundant taxon in the benthic system, live in direct contact with sediments, are present in broad distributions and can also handle relatively high concentrations of metals ensuring chronic exposition. The possibility to work with not only the polychaete but also its tube offers advantages compared to bivalves that generally do not accumulate certain metals in very high levels.

The biogeochemistry of trace metals in nearshore sediments and mussel was studied at 15 stations along a 1000km long transect paralleling the west coast of the Gulf of California (GOC). Total trace metal (Me) and enrichment factor (EFMe) values in sediments were low due to negligible anthropogenic influence in the region. Past copper mining, however, near Santa Rosalia caused concentrations of Pb, Mn, Co, Zn and Cu which were 10–3.3×103 times greater than the average for the rest of the transect. Mussels also showed relatively high trace metal concentrations at the Santa Rosalia stations, but the variability in the spatial distribution was low and had undefined trends. Our results show that, with the exception of Co and Cu, the contamination caused by the copper mine affected sediments to a greater extent than mussels.

Selenium’s (Se) protective effects against mercury (Hg) toxicity have been demonstrated; however, this is seldom considered in health assessments, where dietary exposure is still evaluated by Hg concentration alone. Se:Hg ratios and selenium health benefit values (Se HBVs) offer a more comprehensive seafood safety model. Here we describe total mercury (THg), methylmercury (MeHg) and Se concentrations in fish from a Hg-polluted estuary. Spatial variation in THg, MeHg and Se was evident, though all regions maintained Se:Hg ratio values >1. Se HBV varied between regions and in one region mean negative values (−5.17) were evident. This study provides the first evidence that quoting a single all-encompassing Se HBV is not appropriate when species demonstrate strong site fidelity. It highlights the need for research into Se–Hg relationships in environments with established Hg pollution and reinforces the assertion that Se concentration be considered in assessments of human health risk to Hg exposure.

The growth of maritime transport and oil exploitation activities may increase the risk of oil spills. Thus, plans and actions to prevent or mitigate impacts are needed to minimize the effects caused by oil. However, tools used worldwide to support contingency plans have not been integrated, thus leading to failure in establishing priority areas. This investigation aimed to develop indices of environmental vulnerability to oil (IEVO), by combining information about environmental sensibility to oil and results of numerical modeling of spilled oil. To achieve that, a case study concerning to oil spills scenarios in a subtropical coastal area was designed, and IEVOs were calculated and presented in maps, in order to make the information about the areas’ vulnerability more easily visualized. For summer, the extension of coastline potentially affected by oil was approximately 150km, and most of the coastline presented medium to high vulnerability. For winter, 230km coastline would be affected, from which 75% were classified as medium to high vulnerability. Thus, IEVO maps allowed a rapid and clearer interpretation of the vulnerability of the mapped region, facilitating the planning process and the actions in response to an oil spill.

In order to understand changes in the functioning and the community structure of intertidal ecosystem in sewage-impacted sites, a long-term monitoring coverage study (2004–2011) was carried out on abrasion platforms of the SW Atlantic. The intertidal zone is characterized by the mytilid Brachidontes rodriguezii, an ecosystem engineer. Since the austral spring of 2008, a demographic explosion of an invader polychaetes, Boccardia proboscidea, has produced massive biogenic structures around the sewage discharge outfall. Cover percentage of this polychaete reached almost 100% in sewage-impacted sites but low or no coverage at all in Reference Sites. The density of B. rodriguezii declined due to the biogenic reefs stifles these mytilids. The massive settlement of B. proboscidea among mussels, the rapid growth and the tube construction smothers the mussels in sewage-impacted sites.

Marine bivalves such as oysters are widely used as bioindicators to monitor marine coastal pollution. This study aimed to use B-esterase activity responses in oysters (Crassostrea gigas) cultured in Ebro Delta bays to monitor environmental effects of pesticides. The B esterases investigated were acetylcholinesterase, propionylcholinesterase, and carboxylesterase and their activities were measured in adductor muscle and gills from oysters transplanted in Ebro Delta bays where the are traditionally grown. Enzyme activities were related with physico-chemical parameters and pesticide levels measured in water. Cholinesterase activities measured in gills were unaffected across sites and periods. Conversely, carboxylesterase activities in oyster gills varied across periods and sites and were negatively correlated with residue levels of organophoshporous and carbamate pesticides in water. Therefore, inhibition of carboxylesterase activities can be considered a good indicator of exposure to anti-cholinergic pesticides in oysters.

We examine macrofaunal and physico-chemical responses to organic enrichment beneath salmon farms in contrasting flow environments, and reveal pronounced flow-related differences in the magnitude and spatial extent of effects. Total macrofaunal abundances at high flow sites were nearly an order of magnitude greater than at comparable low flow sites, representing a significant benthic biomass. These very high abundances occurred in conjunction with moderate-to-high species richness, and were evident in the absence of appreciable organic matter accumulation. Biological responses to increasing sulfide were variable; however a significant biological threshold was evident at 1500μM. Macrofaunal responses at high flow sites differed substantially from the Pearson–Rosenberg model. The atypical ecological conditions were attributed to (i) limited accumulation of fine sediments, (ii) maintenance of aerobic conditions in near-surface sediments, and (iii) an abundant food supply. Thus, enhanced resilience to organic waste at well-flushed sites appears related to both biological and physical processes.

Polychlorinated biphenyls, organochlorine pesticides, organotin compounds and triazines were quantified in sediments and bivalves collected in four areas on the Galician coast. One or several species were analysed at each site depending on their availability, including mussels (Mytilus galloprovincialis), cockles (Cerastoderma edule), clams (Venerupis pullastra and Ruditapes decussatus) and razor shells (Ensis siliqua). The general spatial distribution of contaminants was consistent in spite of the different sources of contamination. High inter-species variability was also observed. M. galloprovincialis and V. pullastra showed the highest levels of contaminants and intra-spatial variability, which highlights them as suitable species to be used as sentinel organisms. The area of O Burgo showed some worrisome results: PCB sediment concentrations were within the range that could cause biological effects. Also the level of heptachlor observed in V. pullastra was above limits accepted on edible seafood. Finally TBT concentration in mussels correlated with concentrations causing imposex in snails.