Polychlorinated biphenyls (PCBs) found in marine molluscs could be a serious threat to the health of consumers; however, studies on this subject are limited. To understand this threat, the indicator PCBs (PCB-28, PCB-52, PCB-101, PCB-118, PCB-138, PCB-153 and PCB-180) found in six different kinds of molluscs were determined, and the associated cancer risk for consumers that intake these indicator PCBs via molluscs was assessed. The total concentrations of PCBs in molluscs ranged from 17.51 to 47.43 ng/g (d.w.). The order of contamination levels for indicator PCBs in molluscs was Perna viridis > Ruditapes philippinarum > Crassostrea gigas > Mimachlamys nobilis > Glossaulax didyma > Anadara antiquata. Tri-, tetra- and penta-PCBs were the dominant congeners in molluscs from Haikou City. Tetra-PCBs are the most common PCB, accounting for 38.49% of total PCBs. Compared with previous global studies on PCBs in molluscs, the pollution level of indicator PCBs in the molluscs from Haikou City was lower than most of reports in Europe and China, but higher than those from France and Korea, suggesting a moderate pollution level. The 50% and 95% cancer risks of indicator PCBs in molluscs for adult consumers were 2.75 × 10−7 and 4.32 × 10−7, indicating that the cancer risk was at an acceptable level. Since the dioxin like-PCBs were not analyzed in this study, the cancer risk of PCBs to human health might be underestimated; therefore, more studies on PCB pollution in molluscs are required.

Several dolphin species occur close inshore and in harbours, where underwater noise generated by pile-driving used in wharf construction may constitute an important impact. Such impacts are likely to be greatest on species such as the endangered Hector's dolphin (Cephalorhynchus hectori), which has small home ranges and uses this habitat type routinely. Using automated echolocation detectors in Lyttelton Harbour (New Zealand), we studied the distribution of Hector's dolphins using a gradient sampling design over 92 days within which pile-driving occurred on 46 days. During piling operations, dolphin positive minutes per day decreased at the detector closest to the piling but increased at the mid-harbour detector. Finer-grained analyses showed that close to the piling operation, detections decreased with increasing sound exposure level, that longer piling events were associated with longer reductions in detections, and that effects were long-lasting - detection rates took up to 83 h to return to pre-piling levels.

Total mercury (THg) and δ¹⁵N were analysed in liver and muscle of juvenile green turtles (Chelonia mydas) from a foraging site in southeastern Brazil (~23°S) to evaluate contamination levels and make inferences about the timescale that animals were recruited from oceanic to coastal waters. The values for THg and δ¹⁵N in liver and muscle were 432.2 and 72.8 μg kg⁻¹ and 10.0‰ and 9.2‰, respectively. THg concentrations in tissues indirectly indicated that the main food resources for this consumer (i.e., macroalgae) had negligible levels of this element. Thus, this foraging site could be considered a pristine area in terms of Hg contamination. The THg and δ¹⁵N in liver were derived by more recent food ingestion than those in muscle. The juvenile green turtles that died because of incidental captures in fisheries practiced along this foraging site were individuals newly recruited from oceanic waters.

Concern about the condition of Philippine coral reefs has prompted a recent reassessment of the status of the nation's reefs, the results of which are reported here. This paper presents the largest updated dataset on Philippine coral cover and generic diversity. The dataset was obtained from equally-sized sampling stations on fore-reef slopes of fringing reefs in six biogeographic regions using identical methods. A total of 206 stations were surveyed from 2014 to 2017, and another 101 stations were monitored from 2015 to 2018.The weighted average hard coral cover (HCC) was 22.8% (±1.2 SE) and coral generic diversity averaged 14.5 (±0.5 SE). Both were highest in the fully-formed reefs of the Sulu Sea biogeographic region and lowest in the eastern Philippines. Comparisons of findings with those of previous assessments show the continued decline in coral cover over a larger time scale, with the loss of about a third of the reef corals over the last decade. However, no consistent changes were evident in the 101 monitoring stations from 2015 to 2018 despite the global coral bleaching event. An expanded monitoring program, not just one-off assessments, is recommended to improve reef management in the Philippines.

Oil and gas exploration and marine transport in the Arctic region have put the focus on the ecological risk of the possibly exposed organisms. In the present study, the impacts of sea ice, extreme light regime, various polar region-specific physiological characteristics in polar cod (Boreogadus saida) and their effects on xenobiotic distribution and metabolism are studied. A Bayesian belief network is used to model individual fish toxicity. The enzyme activity in the fish liver and other pertinent organs is used as a proxy for cellular damage and repair and is subsequently linked to toxicity in polar cod. Seasonal baseline variation in enzyme production is also taken into consideration. The model estimates the probability of exposure concentration to cause cytotoxicity and circumvents the need to use the traditionally obtained No Observed Effect Concentration (NOEC). Instead, it uses biotransformation enzyme activity as a basis to estimate the probability of individual cell damages.

Harmful algal blooms (HABs) are one of primary worldwide environmental problems with severe consequences for aquatic ecosystems, human health, marine fisheries and local economy. During the past few decades, coastal waters of China Seas have experienced a significant increase in the occurrence of the HAB events, which is common across the vast majority of coastal waters of the world. Here we report the absence of the widespread increase over the early 21st century in China Seas. Both frequency and coverage area of annual HAB events have decreased at statistically significant rates for the 2000–2017 period. Despite the multiple factors determining the outbreak of HABs, the improvement of water quality in the marginal sea off China and changes in the sea surface temperature in the early 21st century may play an important role in the decrease in the HABs.

The sorption of polybrominated diphenyl ethers (PBDEs) onto polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA) microplastics was analyzed using different kinetic and isotherm models, and under various environmental conditions, including temperature, pH, salinity and dissolved organic matter (DOM). The sorption capacity was in the order of PS > PA > PP > PE, due to the different crystallinity, specific surface area, and surface structure. PS demonstrated the equilibrium sorption capacity, namely, 6.41 ng/g BDE-47, 12.83 ng/g BDE-99, and 14.42 ng/g BDE-153. The second-order kinetic model described the sorption kinetics of PBDEs, and surface sorption was the main mechanism. The sorption of PBDEs by microplastics was a multilayer and physical process. Low temperatures reduced BDE-47 sorption on microplastics, and sorption was a spontaneous and endothermic process. The sorption of BDE-47 was not significantly influenced by pH and salinity. However, DOM exerted a negative effect on the sorption of BDE-47.

To understand tidal disturbance on the colonization dynamics in community functioning of the ciliates in marine ecosystems, a 1-month survey was conducted using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in Korean coastal waters. The results showed considerable differences were detected in community functioning parameters between the two systems. The vagile, flattened forms feeding on periphytic microalgae showed a higher community-weighted mean (CWM) value, and the solitary-colonial pattern represented a more stable temporal variability during the colonization in the PFES system than the CS system. The temporal shift in community functioning of the ciliates showed different ways in both systems. The functional diversity measures generally levelled off at more stable values in the communities with ages of 13–15 days in the PFES system than the CS system. These results imply that the PFES system may be a workable method for bioassessment in marine ecosystems.