For understanding the significance of tidal pumping for driving submarine groundwater discharge (SGD), two time series observations were conducted over tidal cycles in typical mariculture areas of Sanmen Bay, China. Based on ²²⁴Ra and dissolved silicon (DSi), the tide-driven SGD fluxes showed significant negative correlations with tidal height, and were 16.4 ± 5.6 cm d⁻¹ and 21.7 ± 13.9 cm d⁻¹ at two coastal sites of the Sanmen Bay, highlighting the potential of DSi in SGD calculation when coastal waters are on short time scales. Furthermore, nutrient fluxes through tidally influenced SGD were estimated to be 11.5–26.5 mmol m⁻² d⁻¹ for dissolved inorganic nitrogen, 0.06–0.34 mmol m⁻² d⁻¹ for dissolved inorganic phosphorus and 11.5–32.1 mmol m⁻² d⁻¹ for DSi, which were higher than those from surface loadings, revealing that tide-driven SGD with large amounts of nutrient and high N:P ratios may significantly contribute to the development of marine aquaculture.

Marine plastic pollution is a global issue that has calamitous consequences for global economy, biodiversity, human health, and the climate. A few of the studies were carried out on the Gopalpur coast and the current baseline survey was conducted during Covid-19 pandemic lockdown (April–August 2021) and post lockdown (August–September 2021).The survey was covered about 1500 m along the coast, divided into 10 equal zones of each (20 × 150 m²) to collect the plastic debris based on colour, density, and weight. Plastic debris was categorized into 33 types with an average 1.276 g/m² during lockdown and was categorized into 34 types with an average 3.34 g/m² in post lockdown. The results imply that tourism has a greater impact on the beach in terms of pollution when compared with the local sources, which will have a drastic effect on the aesthetics of the beach, neighbouring turtle nesting site and indirectly on human health.

Bacteria biodegradation of immiscible oil requires cell-droplet encounters, surface attachment, and hydrocarbon metabolism. Chemical dispersants are applied to oil spills to reduce the mean dispersed droplet size, thereby increasing the available surface area for attachment, in attempts to facilitate bacterial biodegradation. However, their effectiveness remains contentious as studies have shown that dispersants can inhibit, enhance, or have no effect on biodegradation. Therefore, questions remain on whether dispersants affect surface attachment or cell viability. Here, using microfluidics and time-lapse microscopy, we directly observe the attachment and growth of the marine bacterium, Alcanivorax borkumensis, on stationary crude oil droplets (5 μm <R < 150 μm) in the presence of Corexit 9500. We show that the average colonization time, or the time comprised of encounters, attachment, and growth, is dependent on droplet size and primarily driven by diffusive encounters. Our results suggest that dispersants do not inhibit or enhance these biophysical processes.

The occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis was molecularly investigated in the hemolymph, gills, stomach, hepatopancreas and gonads of the eleven invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (Mediterranean Sea). Out of 11 blue crabs, 6 (54.5%) and 4 (36.4%) were found positive to T. gondii and C. cayetanenis, respectively; parasites were found only in the six females analysed, while the remaining five males resulted negative. Moreover, out of 55 tissues samples, 7 (12.7%) and 8 (14.5%) were positive to T. gondii and C. cayetanensis, respectively with hemolymph and gills being the most infected tissues. This is the first report of the presence of protozoan pathogens in wild crab species collected from a Mediterranean lagoon. The present results may provide a baseline reference on microbial infection in the species for invaded Mediterranean waters, and on the potential health risks related with its consumption if eaten raw.

Abandoned gillnets in the marine environment represent a global environmental risk due to the ghost fishing caused by the nets. Degradation of conventional nylon gillnets was compared to that of nets made of polybutylene succinate co-adipate-co-terephthalate (PBSAT) that are designed to degrade more readily in the environment. Gillnet filaments were incubated in microcosms of natural seawater (SW) and marine sediments at 20 °C over a period of 36 months. Tensile strength tests and scanning electron microscopy analyses showed weakening and degradation of the PBSAT filaments over time, while nylon filaments remained unchanged. Pyrolysis-gas chromatography/mass spectrometry revealed potential PBSAT degradation products associated with the filament surfaces, while nylon degradation products were not detected by these analyses. Microbial communities differed significantly between the biofilms on the nylon and PBSAT filaments. The slow deterioration of the PBSAT gillnet filaments shown here may be beneficial and reduce the ghost fishing periods of these gillnets.

The dispersion of oil droplets near ocean surface is important for evaluating the impact to the environment. Under breaking wave conditions, the surface oil experiences mainly two processes: the generation of oil droplets at/near the water surface, and the transport of oil droplets due to ocean dynamics. We investigated the vertical behavior by incorporating the transport equation and the VDROP model. The transport equation adopted the ocean dynamics by K-profile parameterization (KPP) and the impact of additional turbulence by imposing the energy dissipation rate on the ocean surface. The oil droplet distribution was obtained, and the entrained distribution and entrainment rate was computed. The results shows that although the entrained distribution and the entrainment rate shares certain consistency with previous studies, divergences are also noticed. Accordingly, the model that describes the physics should be adopted to avoid incorrect qualification of the oil concentration dispersed in the ocean.

Heavy metal-contaminated wastes can threaten mangrove forests, one of the most biodiverse ecosystems in the world. The study evaluated the geospatial distribution of heavy metals concentrations in soils, the ecological and human health risks, and metal contents in soil fractions and mangrove organisms in the Botafogo estuary, Brazil, one of the most environmentally impacted estuaries in the country. The metal concentrations exceeded by up to 2.6-fold the geochemical background; 91%, 59%, 64%, 31%, and 82% of the soils were contaminated with Cr, Zn, Pb, Cu, and Ni, respectively. Adverse effects to the biota may occur due to Cr, Cu, Ni and Pb exposures. Contents of clay and organic matter were the main factors governing the distribution of metals in soil, contributing to up to 63% of the total variability. However, the geospatial modeling showed that the predictive ability of these variables varied spatially with the metal and location. The ecological and human health risks assessments indicated that the metal concentrations in soils are safe for the environment and human beings. There was a low transfer of metals from the soil to the biota, with values of sediment-biota accumulation factor (SBAF) and biological accumulation coefficients (BAC) lower than 1.0, except for Zn (SBAF = 13.1). The high Zn bioaccumulation by Crassostrea rhizophorae may be associated with the concentrations of Zn in the bioavailable fractions.

The present report provides data on entanglement of Steller sea lions (SSL) in marine debris on Tyuleniy Island, Sea of Okhotsk. The frequency of entanglement depending on the material, sex, and age of animals was estimated. A total of 133 SSL were recorded as having debris on their bodies, or an average of 22.2 individuals per year. The relative rate of entanglement over the observation years ranged from 1.48 to 1.97% of their total number. The entangled individuals were both males and females of all ages, but young males constituted the largest proportion among them (5.2%). The entangled SSL most frequently (43.2%) had neck collars (the material is not defined) and, less frequently, packaging bands (23.4%), nets (17.7%), and other debris. Most of marine litter found on SSL is associated with commercial fishing activities. On Tyuleniy Island, the rate of SSL entanglement is higher than in the eastern part of the species' range.

Sewage is one of the biggest contributors to coastal pollution. The study was aimed to assess the impact of sewage on coastal water quality of Kanyakumari, the southernmost part of India. A bacteriological survey was made on distribution and abundance of fecal indicators and human pathogenic bacteria and seasonal influence on the bacterial load and antibiotic resistance of the isolates. Samples were collected from sewage discharge point along the eastern shore of Kanyakumari Coast from February 2019 to January 2020. Nine pollution indicator bacteria and pathogenic species such as Escherichia coli, Klebsiella spp., Enterococcus faecalis, Aeromonas spp., Proteus mirabilis, Salmonella typhi, Vibrio cholerae, Shigella spp. and Flavobacterium spp. were isolated from the samples. These isolates were tested against 10 antibiotics, using Kirby Bauer method. All the isolates were resistant to at least two antibiotics. The presence of antibiotic resistant bacteria has been used as bio-indicators of pollution. Hence it is clear that the domestic sewage entering the coast is untreated which might lead a serious impact on human and marine wildlife along coastlines.

Coastal harbor areas are subjected to a myriad of contamination sources with largely unknown effects. Such complex chemical mixtures are difficult to monitor but transcriptomics is a promising approach for such biomonitoring. The present study was designed to verify the use of the Coastal Biosensor for Endocrine Disruption (C-BED) assay, previously developed to detect emerging contaminants and their effects on Mytilus edulis, on another mussel species, Mytilus galloprovincialis. Mussels were caged on St-Florent harbor (contaminated) and on Revellata Bay (reference) for three months. A classical multibiomarkers approach was coupled to the C-BED assay. The results of both approaches were analysed using the Integrated Biomarkers Responses (IBR) and compared to each other. Both approaches demonstrated a higher contamination and probable endocrine disruption of mussels in St-Florent, compared to the reference station. These results confirm that the C-BED assay provides an innovative method to expand our ability to detect emerging contaminants.