We investigated coral bleaching by monitoring colour changes and measuring the delayed fluorescence (DF) of symbiotic dinoflagellates in the hermatypic coral Acropora tenuis, exposed to 1.0 μg/L Irgarol 1051 (photosystem II herbicide) for 14 d. The Irgarol concentration corresponded to those from international port regions of the world. The coral colour and DFs under the control treatment were stable throughout the experiment, whereas under the Irgarol treatment the corals showed gradual bleaching. The Irgarol treatment caused a rapid decrease in the slow decay DF component (10.1–60.0 s), while the fast decay DF component (0.1–10.0 s) decreased significantly after 6 d. The significant correlation between the latter values and the coral colour indicates that if the electron accumulation function of quinones QA and QB is compromised, corals will bleach. The present study will contribute to the understanding of the mechanism involved in bleaching of coral exposed to herbicides.

Here, we report results from a 15-day mesocosm experiment examining changes in estimated oil equivalents (EOEs), n-alkanes (n-C₁₀ to n-C₃₅), polycyclic aromatic hydrocarbons (PAHs) and petroleum biomarkers. Water accommodated fractions (WAF) of oil and diluted chemically enhanced WAF (DCEWAF) were prepared and concentrations of oil residues determined on day 0, 3 and 15, respectively. Significant removals of n-alkane and PAHs were observed starting from day 3. The n-C₁₇/pristane and n-C₁₈/phytane ratios suggested that the n-alkane removal was due to biodegradation in the mesocosms. The ratios of C2-dibenzothiophenes/C2-phenanthrenes (D2/P2) and C3-dibenzothiophenes/C3-phenanthrenes (D3/P3) were found to be stable through the experiment. DCEWAF treatment had longer half-lives for most n-alkanes but shorter half-lives for most PAHs than the WAF treatment. Most petroleum biomarkers were stable throughout the experiment. However, depletion of TAS (tricyclic aromatic steroids) was observed on day 15 of DCEWAF treatment.

Marine genetic resources (MGR) are a new issue in high seas management. Discussion on how to best manage these resources is currently ongoing at the United Nations, within the context of a proposed treaty on the conservation and sustainable use of marine ‘Biodiversity Beyond National Jurisdiction’ (BBNJ), which is expected to be completed in 2020.But how accurately can states measure the potential economic value of resources that still do not have a clear market application? Developing states in particular already suffer from wealth blindness, where they lack the capacity to properly evaluate the economic value or market potential of their marine resources. This article explores the extent to which wealth blindness forms the backdrop to the current debates over the potential for profitably exploiting marine genetic resources, as well as how this relates to demands for capacity building and technology transfer in the BBNJ treaty negotiation process.

In the South Pacific (SP) pearl farming atolls, wind is the main driver of lagoon water circulation, affecting dispersal and survival of pearl oyster larvae. To characterize typical wind conditions in the SP, wind regime classifications are performed from regional climate simulations using the WRF model, for present-day and for the end of the 21st century under RCP8.5 scenario conditions. At the daily time-scale, 4 regimes are identified: a trade-wind, a north-easterly, and two easterly regimes. Their characteristics are driven by large-scale circulation and climate modes of variability. In future projection, all regimes are characterized by a ~15% wind speed increase, while directions and occurrence frequencies undergo marginal changes. At the monthly time-scale that corresponds to pearl oyster pelagic larval duration, nine wind regimes are determined including three regimes with wind reversals. These regimes can be used to model typical lagoon conditions during larval dispersal.

The present work was undertaken to assess the impact of trace element concentration and the status of potential ecological risk in the reef sediments of the Vembar group of islands, Gulf of Mannar Marine National Park, India. Totally, 114 reef sediments (surface) were collected from the Vembar group of islands (Nallathanni Island – 36 samples; Upputhanni Island – 48 samples; Puluvinichalli Island-30 samples). The reef sediments are enriched with sand-sized calcareous particles. The calcium carbonate percentage (CaCO₃) was primarily controlled by the distribution of coral colonies and available lithogenic grains. The pollution load index (PLI) reveals that the majority of the sediments fall under the unpolluted category. Moreover, the potential ecological risk (PERI) and sediment pollution index (SPI) reveals that the Vembar group of islands fall under the low ecological risk category.

The Fundão dam collapse occurred on November 2015 in Mariana city (Brazil), provoking a series of ecological impacts over the Doce river basin and its nearshore environment. However many impacts over fishery target fauna (fish and shrimp) are still unknown or underestimated due to the lack of baseline data in the region. In the present study we assessed the isotopic niches modeled from δ¹³C and δ¹⁵N signatures of six estuarine fish species before and after the impact to assign potential shifts at the population- and community-level. We showed isotopic niche has altered in all studied species irrespective of its trophic group and habitat use. Niche community metrics indicated a depletion of trophic diversity and basal resources of the whole community after the impact. Food web changes as we reported here can impair the energy transfer through the food chain and put at risk the sustainability of small fisheries that rely upon local resources.

Nitrate is the major chemical form of N-nutrient to sustain primary production in Changjiang Estuary and adjacent seawaters. We employed δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ to constrain the source, cycling, and sink of nitrate in early spring. Both δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ differentiate significantly among Changjiang Diluted Water (CDW), Yellow Sea Coastal Current (YSCC), and Taiwan Warm Current (TWC). In coastal areas, nitrate distribution and its isotopes are mainly affected by Changjiang inputs. Chemical fertilizers and sewage & manure originated nitrate jointly contribute the most nitrate in CDW. In offshore areas, nitrification contributes 44 ± 21% of the nitrate in YSCC and 17 ± 16% in TWC; assimilation is the dominant process to remove nitrate in TWC (35 ± 16%). Overall, nitrification and assimilation are the key nitrate cycling processes in early spring and co-shape the offshore distribution pattern of nitrate and its dual isotopes.

In this study, we assessed the Atlantic surfclam (Spisula solidissima) energy budget under different ocean acidification conditions (OA). During 12 weeks, 126 individuals were maintained at three different ρCO₂ concentrations. Every two weeks, individuals were sampled for physiological measurements and scope for growth (SFG). In the high ρCO₂ treatment, clearance rate decreased and excretion rate increased relative to the low ρCO₂ treatment, resulting in reduced SFG. Moreover, oxygen:nitrogen (O:N) excretion ratio dropped, suggesting that a switch in metabolic strategy occurred. The medium ρCO₂ treatment had no significant effects upon SFG; however, metabolic loss increased, suggesting a rise in energy expenditure. In addition, a significant increase in food selection efficiency was observed in the medium treatment, which could be a compensatory reaction to the metabolic over-costs. Results showed that surfclams are particularly sensitive to OA; however, the different compensatory mechanisms observed indicate that they are capable of some temporary resilience.

In this work, microphytobenthos Cylindrotheca closterium was planted on the surface of coastal sediments to investigate its influence on dibutyl phthalate (DBP) degradation in sediments under different nutritional conditions. The results indicated that C. closterium largely utilized nutrients from the overlying water. Addition of nitrogen, phosphorus or silicon increased algal biomass (as chlorophyll a) by 0.97–3.16, 1.75–2.36 and 1.61–3.09 times, respectively, meanwhile it changed bacterial community structure in sediments with C. closterium. Growth of C. closterium was more sensitive to nitrogen content in the overlying water. Inoculation of C. closterium increased the relative abundances of dominant aerobic bacteria by 10–67%. Compared with treatments without C. closterium, inoculation of C. closterium increased DBP degradation percentage in sediments (8.5–18.9% increment), which was positively correlated with chlorophyll a content. Thus, microphytobenthos showed the potential for improving the cleansing of polluted coastal sediments, which was obviously related to nutritional conditions in the overlying water.

In microplastics (MPs) research, there is an urgent need to critically reconsider methodological approaches and results published, since public opinion and political decisions might be based on studies using debatable methods and reporting questionable results. For instance, recent studies claim that MPs induce intestinal damage and that relatively large MPs are transferred to, e.g., livers in fish. However, there is methodological criticism and considerable concern whether MP transfer to surrounding tissues is plausible. Likewise, there is an ongoing discussion in MP research if MPs act as vectors for adsorbed hazardous chemicals. In this study, effects of very small (4–6 μm) and very large (125–500 μm) benzo(a) pyrene (BaP)-spiked polyethylene (PE) particles administered via different uptake routes (food chain vs. direct uptake) were compared in a 21-day zebrafish (Danio rerio) feeding experiment. Particular care was taken to prevent cross-contamination of MPs during dissection and histological sample preparation. In contrast to numerous reports in literature describing similar approaches, independent of exposure route and MP size, no adverse effects could be detected. Likewise, no BaP accumulation could be documented, and MPs were exclusively seen in the lumen of the intestinal tract, which, however, did not induce any histopathological effects. Results indicate that in fish MPs are taken up, pass along the intestinal lumen and are excreted without any symptoms of adverse effects.