Concentrations of PCBs and OCPs were measured in 35 surface sediment samples collected from offshore waters of Central Vietnam. The mean concentrations of PCBs, HCHs, and DDTs in surface sediments were 86.5, 37.0, and 44.5pgg−1, respectively. Additionally, nine PCDDs, eleven PCDFs, and twelve dl-PCBs were also examined in 19 sediment core samples collected from five locations. Concentration of PCDDs, PCDFs, and dl-PCBs ranged from 200 to 460, 0.39 to 2.9, and 1.6 to 22pgg−1, respectively. OCDD was detected at the highest concentration, ranged from 100 to 300pgg−1. Generally, the concentrations of PCDD/Fs at shallower depths were higher, meanwhile the depth profiles of dl-PCBs in sediment cores were different than the depth profiles of PCDD/Fs. The results suggest that the pollution of PCBs might be from many different sources leading to the variation between depths.

Oil slicks were detected using satellite Synthetic Aperture Radar (SAR) images in 2011. We investigated potential origins and regional and seasonal features of oil slick in the Bohai Sea. Distance between oil slicks and potential origins (ships, seaports, and oil exploitation platforms) and the angle at which oil slicks move relative to potential driving forces were evaluated. Most oil slicks were detected along main ship routes rather than around seaports and oil exploitation platforms. Few oil slicks were detected within 20km of seaports. Directions of oil slicks movement were much more strongly correlated with directions of ship routes than with directions of winds and currents. These findings support the premise that oil slicks in the Bohai Sea most likely originate from illegal disposal of oil-polluted wastes from ships. Seasonal variation of oil slicks followed an annual cycle, with a peak in August and a trough in December.

Increasing concerns over decreasing water quality and the state of coral reefs and seagrass meadows along the inshore and mid-shelf regions of the Great Barrier Reef has led to a large-scale government catchment sediment and nutrient reduction program. However the mechanistic understanding of how fine sediments washed out of catchments and transported within flood plumes leads to ongoing increases in turbidity at locations far downstream from estuaries long after flood plumes have dissipated is poorly understood. Essential criteria which need to be met in order for catchment-derived sediments to play a major role in nearshore water quality are proposed. Preliminary estimates of these essential criteria suggest that it is dynamically possible for fine sediments washed out of catchments during floods to be preferentially re-mobilised at downstream locations following the dissipation of flood plumes. However the longer-term influence of catchment-derived material on water quality is dependent upon the rate of degradation of floc particles that fall out of flood plumes and the rate of background deposition; neither of which are well quantified.

On January 31, 2014, an oil spill accident occurred in Yeosu, South Korea. A total 800–899kl of oil from the pipeline was spilled into the sea. After the oil spill, the KIOST (Korea Institute of Ocean Science & Technology) researched PAHs (polycyclic aromatic hydrocarbons) in various media, but sedimentary PAHs were not analyzed despite their longer persistency than in other media. Therefore, this study examined PAH levels in intertidal sediments around Gwangyang Bay and identified PAH sources using oil fingerprinting. PAH residual levels showed a dramatic decrease during the four months after the accident and then remained at a relatively constant level. Analysis through regression equations indicate that this study area is likely to be restored to the PAH levels prior to the accident. Furthermore, the source analysis and oil fingerprinting analysis showed that PAH contamination in this study was unlikely to have originated from the spilled oil.

In Guadeloupe, many marine organisms are affected by an organochlorine pollution used in the past by the banana industry to fight against the banana weevil. In the present study, we evaluated the level of contamination of the invasive Indo-Pacific lionfish, Pterois volitans, all around the island. Concentrations of chlordecone varied from 3 to 144μg.kg−1 wet weight. The highest concentrations were recorded when samples were captured in the marine zones located downstream of the previous banana plantations. This contamination seemed to decrease rapidly with the distance from the coast. Mean concentration of chlordecone in Pterois volitans was higher than that of five other fish species collected in similar sites. Due to its position at the top of the trophic web, lionfish was affected by bioaccumulation of chlordecone and can be used as a sentinel species to assess and control the level of contamination of the marine environment by chlordecone.

Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm−2, physical disturbance depth of 16.4cm, bacterial density of 0.18Lm−2, and polychaetes biomass of 0.16kgm−2, respectively. These results emphasize the value of combining different species in field-based bioremediation.

Genitors of the Pacific oyster Crassostrea gigas were submitted during gametogenesis to a short pulse exposure to the herbicide diuron at a realistic environmental concentration. Histological analysis showed no effect of diuron on gametogenesis course, sex ratio and reproductive effort. A non-significant increase in testosterone and progesterone levels was observed in genitors exposed to the herbicide. At cell level, diuron exposure was shown to modulate the phagocytic activity of circulating hemocytes. The results of a transcriptional analysis showed that diuron affected the expression of genes belonging to functions known to play a major role during oyster gametogenesis such as gene transcription regulation, DNA replication and repair, DNA methylation and cytokinesis. Taking into account the results we previously obtained on the same genitors, this study showed a negative effect of diuron on oyster reproduction by inducing both structural and functional modifications of the DNA.

Tropical shrimp aquaculture systems in New Caledonia regularly face major crises resulting from outbreaks of Vibrio infections. Ponds are highly dynamic and challenging environments and display a wide range of trophic conditions. In farms affected by vibriosis, phytoplankton biomass and composition are highly variable. These conditions may promote the development of harmful algae increasing shrimp susceptibility to bacterial infections. Phytoplankton compartment before and during mortality outbreaks was monitored at a shrimp farm that has been regularly and highly impacted by these diseases. Combining information from flow cytometry, microscopy, pigment and phylogenetic analysis, the presence of Picocyanobacteria, Prasinophyceae and Diatomophyceae were detected as dominant phytoplankton groups and Cryptophyceae, Prymnesiophyceae and Dinophyceae as minor components. At the onset of the first shrimp mortalities, Bacillariophyceae increased while Cyanobacteria, Prymnesiophyceae and Dinophyceae decreased in the water column, followed by proliferation of Prasinophyceae. Several taxa were identified as potential harmful algae (Cyanobacteria, dinoflagellates and Phaeocystis).

In coastal areas, demographic increase is likely to result in greater numbers of recreational users, with potential consequences on marine biodiversity. These effects may also occur within Marine Protected Areas (MPAs), which are popular with recreational users. Our analysis builds on data collected over a ten-year period during three year-round surveys to appraise changes in recreational boating activities in coral ecosystems. Results show that the number of boaters has greatly increased, particularly so within MPAs during weekends and the warm season, when peaks in boat numbers have become more frequent. We also observed that the number of anchored boats has increased over the period. These changes may be resulting in biophysical impacts that could be detrimental to conservation objectives in MPAs. This steady increase over time may cause changes in the spatial and temporal distribution of users and in their practices, thus highlighting the importance of monitoring recreational activities.