The impacts of ocean acidification on coastal biofilms are poorly understood. Carbon dioxide vent areas provide an opportunity to make predictions about the impacts of ocean acidification. We compared biofilms that colonised glass slides in areas exposed to ambient and elevated levels of pCO₂ along a coastal pH gradient, with biofilms grown at ambient and reduced light levels. Biofilm production was highest under ambient light levels, but under both light regimes biofilm production was enhanced in seawater with high pCO₂. Uronic acids are a component of biofilms and increased significantly with high pCO₂. Bacteria and Eukarya denaturing gradient gel electrophoresis profile analysis showed clear differences in the structures of ambient and reduced light biofilm communities, and biofilms grown at high pCO₂ compared with ambient conditions. This study characterises biofilm response to natural seabed CO₂ seeps and provides a baseline understanding of how coastal ecosystems may respond to increased pCO₂ levels.

Polycyclic aromatic hydrocarbons (PAHs) were measured in plasma samples of 162 juvenile loggerhead sea turtles (Caretta caretta) from Canary Islands, and 205 adult nesting loggerheads from Cape Verde. All the 367 samples showed detectable values of some type of PAH. Phenanthrene was the PAH most frequently detected and at the highest concentration in both populations. Median concentrations of ∑PAHs in the plasma of loggerheads from the Canary Islands and Cape Verde were similar (5.5 and 4.6ng/ml, respectively). Di- and tri-cyclic PAHs were predominant in both populations suggesting petrogenic origin rather than urban sources of PAHs. In the group of turtles from Canary Islands, there was evident an increasing level of contamination over the last few years. The present study represents the first data of contamination by PAHs in sea turtles from the studied areas.

The discharge of sewage into the Antarctic marine environments by scientific stations has resulted in local changes in these pristine sites. To assess the distribution and concentration of sewage indicators from the Brazilian Antarctic station, sediments were sampled during the 2009/10 austral summer at four points (water depth of 20 and 60m). Concentrations of faecal sterols and linear alkylbenzenes (LABs) ranged from <0.01 to 0.17μgg⁻¹ and <1.0 to 46.5ngg⁻¹ dry weight, respectively. Maximum concentration of faecal sterols was similar to the value previously calculated as the background level for this area (0.19μgg⁻¹), and it is lower than the concentration observed in previous studies (1997–2008), whereas the LABs concentrations remained practically constant (35ngg⁻¹). Despite the low concentrations of sewage markers, the permanent human activities in the region require monitoring programs to determine continuing trends and prevent the increase of anthropogenic impacts.

Responses of biological indices and oxidative stress biomarkers were studied in the giant clam Tridacna maxima and in the fish Epinephelus merra collected from two sites differing by their level of contamination in the French Polynesian Moorea island. Higher levels of catalase (CAT), glutathione-S-transferases (GST) and thiobarbituric acid reactive substances (TBARs) were observed in the hepatopancreas of T. maxima and in the liver of E. merra compared to muscle. CAT and TBARs levels were significantly higher in the hepatopancreas of clams collected from the impacted site (Vaiare) compared to the reference site (bay of Cook). The same pattern was observed for TBARs levels in the liver of E. merra. These results indicate that both organisms from the impacted site were exposed to contaminants leading to an oxidative stress and demonstrate, for the first time, the usefulness of T. maxima and E. merra as sentinel species for biomonitoring reef environments.

Respiration and calcium carbonate (CaCO₃) production by the farmed short-neck clam Ruditapes philippinarum were calculated to assess their importance as carbon dioxide (CO₂) sink/source in a lagoon of the Po Delta River (Italy). Biomass and calcimass were established by monthly harvests during a 1-year period (2009). The ratio of CO₂ released to CaCO₃ precipitated was calculated as a function of the near-bottom temperature. From our estimates, R. philippinarum sequestered [Formula: see text] for shell formation, but the CO₂ fluxes due to respiration and calcification resulted 22.7 and 5.56 [Formula: see text] , respectively. Clam farming seems therefore to be a significant additional source of CO₂ to seawater.

Contaminated sediments continue to be a global problem that is too often not addressed in a logical, tiered framework. Such frameworks, when they exist, typically are restricted to assessment and prioritization and do not include possible remedies with accompanying follow-up monitoring to ensure those remedies were successful and further remedies are not necessary. A logical, tiered framework that encompasses all of the above (i.e., assessment through to post-remedy monitoring) is described. This framework was developed by the Canadian Government for use in Canada but has wider applications.

Degradation of coastal ecosystems in the Great Barrier Reef (GBR), Australia, has been linked with a decline in water quality from land-based runoff. This paper examines the reduction in current end-of-catchment loads required for total suspended solids (TSS) and dissolved inorganic nitrogen (DIN) to achieve GBR water quality guidelines. Based on first-order estimates of sustainable pollutant loads, current TSS and DIN loads would need to be reduced by approximately 7000ktons/y (41%) and 6000tons/y (38%), respectively. Next, these estimated reductions for TSS and DIN are compared with Reef Plan targets for anthropogenic sediment (−20% by 2020) and nitrogen (−50% by 2013) loads. If successful, these targets will accomplish approximately 40% of TSS and 92% of DIN load reductions required to achieve sustainable loads to the GBR lagoon. These first-order estimates elucidate the need to establish ecologically relevant targets for river pollutant loads to the GBR for management and policy.

Sorption of anionic perfluorooctane sulfonate (PFOS) on marine sediment was investigated in detail. It was found that solution ionic composition and sediment-specific parameters played important roles in affecting the sorption of PFOS. The results indicated that sorption of PFOS in seawater to marine sediments was strong (∼10 times higher than that in freshwater) and nonlinear (Freundlich nF values of 0.77–0.96). The sorption affinity was well correlated with sediment organic carbon content, indicating the importance of hydrophobic interactions. At a PFOS aqueous concentration of 10μg/L, PFOS distribution coefficients increased with the increasing salinity in solution, with an average rate of 0.48±0.03log units per a log unit of salinity. Further studies demonstrated that among common ions contributing to the salinity in seawater, dissolved calcium and magnesium are dominantly responsible for the sorption-enhancing effect of salinity for PFOS. This work will aid in better understanding of PFOS sorption mechanisms, and be useful for fate modeling of this class of contaminants in the marine environment.

Marine sediment preserves a useful archive for contaminants and other properties that associate with particles. However, biomixing of sediments can smear the record on a scale of years to thousands of years, depending on sedimentation rate and on the depth and vigour of mixing within a particular sediment. Where such mixing occurs, dates can no longer be associated with discrete sediment depths. Nevertheless, much can still be learned from biomixed profiles, provided that mixing is accounted for. With no modelling at all, it is possible to calculate an inventory of a contaminant at a site and a maximum possible sedimentation rate, and to determine whether the contaminant has increased or decreased over time. Radiodating the core with ²¹⁰Pb permits the estimation of sedimentation and mixing rates, which can be combined with the surface contaminant concentration to estimate an approximate flux of the contaminant. Numerical models that incorporate sedimentation and mixing rates (determined using ²¹⁰Pb and other transient signals with known deposition histories) can provide the basis to propose plausible histories for contaminant fluxes.