Previous studies conducted on Daya Bay implied that the bay had been undergoing potential phosphorus limitation. In this context, alkaline phosphatase activity (APA) and the associated microbes were investigated in three different seasons in Daya Bay, South China Sea. Both bulk-community (fractioned into dissolved and particulate) and single-cell assays of APA were used to estimate the P status of phytoplankton at the community and species level. Unexpected high potential APA (Vmax) was observed in Daya Bay. Bulk APA showed that the maximum value in the spring (mean 583.26 nM h−1) corresponded well to low phosphate concentration. Furthermore, particulate APA (P-APA) showed an inverse hyperbolic relationship with phosphate, implying the coexistence of both constitutive and inducible AP; meanwhile, a threshold phosphate concentration for the transition from high to low APA was found around 0.2 μM in our study. P-APA and dissolved APA (D-APA) exhibited a tight link with phytoplankton and bacteria, which indicated that both of them were two main carriers of the enzyme. During the spring cruise, we encountered a small-scaled bloom of Gymnodinium that was probably at a declining phase. Extreme high levels of bulk and D-APA were characterized at this spring bloom event, and we suspected that bacteria especially active bacteria played an important role in APA production and partitioning at the post-bloom phase. In Daya Bay, diatoms were the dominant phytoplankton groups and percentages of ELF (Enzyme Labelled Fluorescence) labelled diatoms followed the same seasonal fluctuation as bulk APA, which suggested that diatoms were responsible for major variations of the bulk AP activity except for the spring bloom. Taken together, we considered that phytoplankton may be experiencing more P stress in spring and that the mineralization of organic P via alkaline phosphatase may help phytoplankton overcome P deficiency.

Natural radioactivity content and heavy metal concentration in the intertidal zone sand samples from the southern region of Tamil Nadu coast, India, have been analyzed using gamma ray spectrometer and ICP-OES, respectively. From gamma spectral analysis, the average radioactivity contents of ²³⁸U, ²³²Th, and ⁴⁰K in the intertidal zone sand samples are 12.13±4.21, 59.03±4.26, and 197.03±26.24Bq/kg, respectively. The average radioactivity content of ²³²Th alone is higher than the world average value. From the heavy metal analysis, the average Cd, Cr, Cu, Ni, Pb, and Zn concentrations are 3.1, 80.24, 82.84, 23.66, 91.67, and 137.07ppm, respectively. The average Cr and Ni concentrations are lower, whereas other four metal (Cd, Cu, Pb, and Zn) concentrations are higher than world surface rock average values. From pollution assessment parameter values, the pollution level is “uncontaminated to moderately contaminated” in the study area.

Eight touristic beaches along the north coast of Santa Catarina Island, Brazil were assessed to determine litter influence on scenic quality. The application of the Coastal Scenic Evaluation System (CSES) categorized these beaches into four of the five available classes. Six of the investigated beaches belong to Class III (n = 3) and V (n = 3), while two beaches correspond to Class II and Class IV. Class I beaches were not found. A total amount of 4291 litter items weighing 29 kg were collected with average abundances of 0.29 items m2. Beach user's habits as well bad management practices along the adjoining river basins play an essential role on litter source, and are directly responsible for the decline of scenic quality of Santa Catarina Island Beaches. In fact, litter has a direct relation with the low scenic scores determined in the surveyed beaches.

We investigated at the single cell level during 16months (June 2012 to September 2013) the temporal distribution of picophytoplankton (picoeukaryotes, Synechococcus and Prochlorococcus) communities in two contrasted ecosystems: the Bay of Bizerte characterised by an oligotrophic regime typical of the Mediterranean Sea and the Bizerte Lagoon that exhibits a mesotrophic/eutrophic state. We aimed at depicting seasonal variations and quantifying the relationships between the environmental factors and the structure and abundance of picophytoplankton communities. Results showed that picophytoplankton groups were able to grow under a wide range of environmental conditions varying seasonally, although their abundances and contributions to the total chlorophyll biomass significantly varied and showed importance in the Bay of Bizerte. Synechococcus was the most abundant group reaching 225∗103cells·cm−3 in the Bay and 278∗103cells·cm−3 in the lagoon. This group was present all over the year in both ecosystems. Structural equation model results pointed out a different configuration regarding the picophytoplankton environmental drivers. The complexity of the configuration, i.e. number of significant links within the system, decreased under enhanced eutrophication conditions. The less exposure to anthropogenic stress, i.e. in the Bay of Bizerte, highlight a larger role of nutrient and hydrological conditions on the seasonal variations of picophytoplankton, whereas a negative effect of eutrophication on picophytoplankton communities was unveiled in the Bizerte Lagoon. We stress that such influence may be exacerbated under expected scenarios of Mediterranean warming conditions and nutrient release in coastal ecosystems.

The performance of oil spill models is strongly influenced by multiple parameters. In this study, we explored the ability of a genetic algorithm (GA) to determine optimal parameters without the need for time-consuming manual attempts. An evaluation function integrating the percentage of coincidence between the predicted polluted area and the observed spill area was proposed for measuring the performance of a Lagrangian oil particle model. To maximise the objective function, the oil spill was run numerous times with continuously optimised parameters. After many generations, the GA effectively reduced discrepancies between model results and observations of a real oil spill. Subsequent validation indicated that the oil spill model predicted oil slick patterns with reasonable accuracy when equipped with optimal parameters. Furthermore, multiple objective optimisation for observations at different times contributed to better model performance.

The increasing global contamination of plastics in marine environments is raising public concerns about the potential hazards of microplastics to environmental and human health. Microplastics formed by the breakdown of larger plastics are typically irregular in shape. The objective of this study was to compare the effects of spherical or irregular shapes of microplastics on changes in organ distribution, swimming behaviors, gene expression, and enzyme activities in sheepshead minnow (Cyprinodon variegatus). Both types of microplastics accumulated in the digestive system, causing intestinal distention. However, when compared to spherical microplastics, irregular microplastics decreased swimming behavior (i.e., total distance travelled and maximum velocity) of sheepshead minnow. Both microplastics generated cellular reactive oxygen species (ROS), while ROS-related molecular changes (i.e., transcriptional and enzymatic characteristics) differed. This study provides toxicological insights into the impacts of environmentally relevant (fragmented) microplastics on fish and improves our understanding of the environmental effects of microplastics in the ecosystem.

This paper describes oil spill stakeholder engagement in a recent comparative risk assessment (CRA) project that examined the tradeoffs associated with a hypothetical offshore well blowout in the Gulf of Mexico, with a specific focus on subsea dispersant injection (SSDI) at the wellhead. SSDI is a new technology deployed during the Deepwater Horizon (DWH) oil spill response. Oil spill stakeholders include decision makers, who will consider whether to integrate SSDI into future tradeoff decisions. This CRA considered the tradeoffs associated with three sets of response strategies: (1) no intervention; (2) mechanical recovery, in-situ burning, and surface dispersants; and, (3) SSDI in addition to responses in (2). For context, the paper begins with a historical review of U.S. policy and engagement with oil spill stakeholders regarding dispersants. Stakeholder activities throughout the project involved decision-maker representatives and their advisors to inform the approach and consider CRA utility in future oil spill preparedness.

This study was carried out to evaluate the distribution, enrichment and ecological risk of heavy metals (arsenic (As), zinc (Zn), manganese (Mn), copper (Cu) and lead (Pb)) concentration in Kuala Selangor estuary at the Kuala Selangor Nature Park. The results suggested that As and Pb in sediment were as high as the background value, suggesting the presence of anthropogenic contamination. The risk assessment of sediment Igeo, CD, and PERI, on the other hand, showed low risk of heavy metals in Kuala Selangor estuary. Meanwhile, risk assessment code (RAC) results showed that Mn, As and Zn presented medium to high level of environmental risk. The translocation factor and bioaccumulation factors of heavy metal concentration by mangrove vegetation showed a variety of trends, which indicates the different partitioning and uptake ability of heavy metal in the tissues of different mangrove species. Therefore, underscores the importance of preserving the high diversity of mangroves at securing the health and productivity of the coastal region. These results may play a critical role in facilitating decision makers in managing the sustainability of mangrove forests.

Spatial dynamics of heavy metals (Cd, Cu, Fe, Pb, and Zn) and metalloid As were investigated along the sedimentary column, inside and outside mangrove stands, and within the upper, middle, and lower Mangawhai Estuary, New Zealand. Organic matter contents (1.89 to 17.15%) were 10 times higher inside versus outside mangroves, and decreased sharply with depth to 30 cm. Cu, Fe, and Zn were highest in the upper estuary and Pb was highest close to a road (lower estuary), reflecting road run-off. A mangrove island (lower estuary; high energy) had lowest heavy metal and highest As concentrations (resulting from high absorption of As by the carbonate rich sediments). Most of the analysed sediment parameters in our study were higher inside versus outside mangroves, suggesting the accumulation of organic matter and build up capacity to buffer pollutants. Our results show that mangrove stands tend to accumulate heavy metals and may act as natural filters of pollution of coastal waterways.

Few studies focus on the effects of aluminum (Al) on marine nitrogen-fixing cyanobacteria, which play important roles in the ocean nitrogen cycling. To examine the effects of Al on the nitrogen-fixing cyanobacteria, bioassay experiments in the oligotrophic South China Sea (SCS) and culture of Crocosphaera watsonii in the laboratory were conducted. Field data showed that 200 nM Al stimulated the growth and the nitrogenase gene expression of Trichodesmium and unicellular diazotrophic cyanobacterium group A, and the nitrogen fixation rates of the whole community. Laboratory experiments demonstrated that Al stimulated the growth and nitrogen fixation of C. watsonii under phosphorus limited conditions. Both field and laboratory results indicated that Al could stimulate the growth of diazotrophs and nitrogen fixation in oligotrophic oceans such as the SCS, which is likely related to the utilization of phosphorus, implying that Al plays an important role in the ocean nitrogen and carbon cycles by influencing nitrogen fixation.