In 2008–2018, 1458 georeferenced samples of clams and 343 of mussels were harvested in Italy from classified areas along Marche coast and analyzed within food-safety monitoring plans. Pb, Cd, V, Ni, Cr, and As median levels (mg kg⁻¹) were 0.09, 0.08, 0.29, 0.77, 0.35, and 2.35 in clams and 0.16, 0.15, 0.46, 0.48, 0.25, and 3.34 in mussels. The reported levels were comparable with the published ones, and Hg always fell below LOQ (0.025 mg kg⁻¹). Pb and Cd datasets, based on quarterly results, show a decreasing trend in clams and constant baseline value for mussels. Time-trends and forecasting models represent an asset to predict emerging food safety/security risks. The metal levels in mussels and clams from the same area allow environmental safety assessment and thus enable the evaluation of contaminants in both water column and sediment. Monitoring of elements that are not regulated may help in preserving food and environmental safety.

Hemocytes are the main immunologic parameters for invertebrate organisms as a response to diseases and pollutions. This study was aimed to reveal the relations between pollution and the total and differential hemocytes numbers. The gulf of İzmir was selected as location for sampling due to its contaminated by different anthropogenic pollutants mainly industrial effects. The effects of the pollutants were investigated on the mussels that have been collected from eight stations in the Izmir Bay (1- Inciralti, 2- Göztepe 3-Konak-4- Pasaport 5-Alsancak, 6-Karşıyaka, 7-Bostanlı), which are known as the most polluted part of inner Bay of Izmir (Western Coast of Turkey) and 8-Foça, (an anthropogenically industrialized and shipping -impacted area). The pollution effects in the bay were determined on hemolymphs by biomarkers such as total hemocyte counts (THCs) and differential hemocyte counts (DHCs). Microscopic examinations have shown the statistical differences at THCs and DHCs. The highest total hemocyte number was determined in the station 7 (Bostanlı) and the lowest in the station 4 (Pasaport) (P < 0.05). The number of total hemocyte counts were not differed significantly in the Stations among 2 (Göztepe), 5 (Alsancak) and 6 (Karşıyaka), and between Stations 8 (Foça) and 1 (Inciraltı) (P > 0.05). In addition, there have been significant differences in subpopulation according to differential hemocyte numbers. The results indicate that the station 8 (reference site-Foça) has the highest agranulocyte number while station 7 (Bostanlı) and the station 1 (İnciraltı) have the lowest agranulocyte numbers (P < 0.05). As for the basophilic hemocyte numbers, this situation was reversed highest number in station 1 (Inciraltı) and 7 (Bostanlı) and lowest in the station 8 (Foça) (p < 0.05). The station 4 (Pasaport) has the highest eosinophilic hemocyte number while station 8 (Foça) has the lowest. We concluded that differential hemocytes counts are more sensitive as biomarker with the highest numbers of agranulocytes and lowest numbers of eosinophilic and basophilic hemocytes in reference site.

Paint particles are part of the increasingly important microplastics (MPs) pollution of our oceans. They contain polyurethanes, polyesters, polyacrylates, polystyrenes, alkyls and epoxies. In spite of their prevalence, paint fragments are often excluded from MP audits. This review, citing 127 references, discusses detection, characteristics, sources and ecological effects of paint fragments in our oceans, as well as the abundance of paint fragments in MP samples around the world and their colonization by marine microorganisms, which differs from that of non-paint MPs. Paint MPs arise from shipping and boating activities, road markings and external surfaces of buildings. Many paint fragments come from antifouling paints used on commercial vessels and leisure boats; these may be regarded as particular pollutants, not only containing but also leaching heavy metals and biocides. Some effects of antifouling paint particles on aquatic biota are caused by these toxins. Paint particles are an understudied portion of marine MP pollution.

Droplet size substantially affects the fate of oil released from deep subsea leaks. A baseline dataset of volume-median droplet diameters (d₅₀), culled from ~250 laboratory observations, is used to validate seven droplet-size models. Four models compare reasonably well, having 95% confidence limits in d₅₀ of ~±50%. Simulations with a near-field fate model (TAMOC) reveals that the four best-performing models, with d₅₀ of 1.3–2.2 mm, agree similarly with observed fractionation of petroleum compounds in the water column during June 4–July 15, 2010. Model results suggest that, had a higher dose of dispersant been applied at the wellhead during Deepwater Horizon oil spill (DWH), the d₅₀ would have dropped by an order of magnitude, reducing surfacing C₁–C₉ volatiles by 3.5×. Model uncertainty is found to be substantial for DWH-like blowouts treated with chemical dispersants, suggesting the need for further droplet-size model improvement.

Coral Ba/Ca is a proxy for seawater barium concentration that varies with upwelling, terrigenous input, and marine productivity whereas coral Sr/Ca varies with temperature. We examine monthly coral Ba/Ca and Sr/Ca before and during offshore oil exploration in a Siderastrea siderea coral from West Flower Garden Bank located on the continental shelf edge in the Gulf of Mexico. Coral Ba/Ca variations lack pulses driven by upwelling or river outflow and are not in sync with coral Sr/Ca that exhibit a different seasonal pattern. Seasonal variations in chlorophyll-a concentration negatively correlate with coral Ba/Ca explaining 25% of that variability. A significant increase in mean coral Ba/Ca of 1.76 μmol/mol between 1931–1944 and 1976–2004 corresponds to the increase in the United States barite production and consumption primarily used in offshore oil drilling, which escalated in the 1970s, suggesting oil drilling operations are increasing seawater Ba concentration in the Gulf of Mexico.

Microplastics are gaining worldwide attention due to their omnipresence. The marine environment is one of the most affected systems; especially the sediment compartment. Microplastic separation from the sediment matrix is the first step to evaluate its abundance and availability. Nevertheless, a lack of consistency in extraction protocols is a fact. This paper describes the optimization of the microplastic extraction procedure from marine sediments. The Plackett-Burman saturated factorial design was used to identify the significant factors and to select optimum working conditions. With this purpose, the following variables were studied: the number of extractions; the amount of sediment; the settling time; the density separation solution volume; the agitation time and the suitability of using wet or freeze-dried sediment. The Plackett-Burman design has revealed that the most statistically significant variables were sediment mass and agitation time. The optimized method was applied for two marine sediments collected in the Mar Menor Lagoon.

Systematic Conservation Planning (SCP) offers concepts and toolboxes to make spatial decisions on where to focus conservation actions while minimizing a variety of costs to stakeholders. Thirty-four studies of Pacific Ocean Tropical Islands were scrutinized to categorize past and current types of applications. It appeared that scenarios were often built on a biodiversity representation objective, opportunity costs for fishers was the most frequent cost factor, and an evolution from simple to sophisticated scenarios followed the need to maximize resilience and connectivity while mitigating climate change impacts. However, proxies and models were often not validated, pointing to data quality issues. Customary management by local communities motivated applications specific to the Pacific region, but several island features remained ignored, including invertebrate fishing, ciguatera poisoning and mariculture. Fourteen recommendations are provided to enhance scenarios' robustness, island specificities integration, complex modelling accuracy, and better use of SCP for island management.

Different litter types accumulate in all marine environments. Plastics are of special interest because of their high abundance and possible threats to marine organisms. Polymer type is crucial for their distribution and fate in marine environments. Seafloor litter abundance and composition in the Baltic and North Sea were analysed based on three sampling campaigns according to the protocol of ICES International Bottom Trawl Survey. Polymers were identified via attenuated total reflection-Fourier transform infrared spectroscopy. General litter abundances differed significantly between the Baltic and North Sea with 9.6 items/km² and 70.7 items/km², respectively. Plastic built the dominating litter group in both seas (62.2% and 91.3%, respectively). Polymer identification revealed clear dominance of polyethylene, polypropylene and polyamide. Most polymers were positively buoyant in seawater (89.5%), thereby excluding polymer density as the main driver of vertical plastic litter transportation. Plastics at the seafloor basically reflected the entirety of polymers entering marine environments.

The contamination of estuaries by heavy metals from anthropogenic activities in the industrial, domestic, and agricultural sectors is a global concern. In this study, the Cr, Fe, and Mn levels in the suspended particulate matter (SPM) were analyzed in estuarine waters from Bahia Blanca Estuary, during 2014–2015. The values of particulate Cr ranged from 7.33 to 35.20 μg g⁻¹, which could be associated to several anthropogenic sources. The positive correlations found between Cr and Chlorophyll-a, and Cr and particulate organic carbon (POC) suggest the strong influence of phytoplankton on the adsorption of this metal and on the increase of particulate Cr. Negative correlations were found between Cr and DO and between Cr and pH, which could indicate an increasing trend in the dissolved form of Cr. This study suggests that the physical-chemical characteristics of the water column as well as phytoplankton and POC dynamics influence the behavior of Cr in this estuary.

Benthic exchanges of oxygen and nutrient at the sediment-water interface were investigated under light and dark conditions at 5 selected sites in a sub-tropical atoll. Mean oxygen fluxes were - 1316.5 ± 242.0 μmol m⁻² h⁻¹ and mean effluxes of oxygen under light conditions were 2231.7 ± 626.4 μmol m⁻² h⁻¹, presumably due to microphytobenthos present at the sediment-water interface. The consequences of this high related productivity was a systematic consumption of nutrients (DIN, PO₄ and Si(OH)₄) during almost all light incubations, contrasting with the effluxes of nutrients during dark incubations. Our results suggest that the sediments were net autotrophic and the oxygen balance in favor of microbenthic production when compared to community demand. Diurnal rates of gross benthic primary productivity were high (3423 ± 1192 μmol m⁻² h⁻¹) which emphasize the role of microphytobenthos in maintaining the oxygen reservoir in tropical lagoons.