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.

Effects of household post-consumer plastics and tyre rubber on a Baltic Sea copepod Limnocalanus macrurus were assessed. Fragments of commercial recycled low-density polyethylene vegetable bags and rubber originating from recycled car tyres were incubated in seawater, and the copepods were exposed to the filtrate of the water. L. macrurus experienced erratic swimming behaviour and increased mortality in the filtrate of unwashed vegetable bags, containing elevated concentrations of alcohols, organic acids and copper. Responses of the antioxidant defence system (ADS) were recorded in copepods exposed to rubber treatments containing high concentrations of zinc. Significant responses in the ADS enzymes indicate that reactive oxygen species (ROS) formation was exceeding the detoxification capacity of the ADS which may further lead to prolonged state of oxidative stress. Observed effects of exposure on the biochemical level coincide with impaired swimming activity of the copepods, indicating possible irreversible cellular responses leading to behavioural changes and mortality.

Mangroves are known to provide many ecosystem services, however there is little information on their potential role to cap and immobilise toxic levels of total petroleum hydrocarbons (TPH). Using an Australian case study, we investigated the capacity of planted mangroves (Avicennia marina) to immobilise TPH within a small embayment (Stony Creek, Victoria, Australia) subjected to minor oil spills throughout the 1980s. Mangroves were planted on the oil rich strata in 1984 to rehabilitate the site. Currently the area is covered with a dense mangrove forest. One-meter-long sediment cores revealed that mangroves have formed a thick (up to 30 cm) organic layer above the TPH-contaminated sediments, accumulating on average 6.6 mm of sediment per year. Mean TPH levels below this organic layer (30–50 cm) are extremely toxic (30,441.6 mg kg⁻¹), exceeding safety thresholds up to 220-fold which is eight times higher when compared to top layer (0–10 cm).

Little is known about the combined effect of environmental factors and contaminants on commercially important marine species, and whether this effect differs by sex. In this study, blue mussels were exposed for seven days to both single and combined stressors (i.e., +3 °C elevated temperature and two environmentally relevant concentrations of the plastic softener DEHP, 0.5 and 50 μg/l) in a factorial design. Males were observed to be more sensitive to high temperature, demonstrated by the significant increase in out-of-season spawning gonads and higher gene expression of the antioxidant catalase and the estrogen receptor genes. On the other hand, while the gametogenesis cycle in females was more resilient than in males, DEHP exposure altered the estrogen-related receptor gene expression.We show that the combined stressors DEHP and increased temperature, in environmentally relevant magnitudes, have different consequences in male and female mussels, with the potential to impact the timing and breeding season success in Mytilus spp.

The surface intertidal sediments in the Pearl River Estuary of China were analyzed from multiple perspectives, including the distribution characteristics, potential sources, and biological risks of polycyclic aromatic hydrocarbons (PAHs). The average concentration of PAHs, ranging from 73.68 ng/g to 933.25 ng/g, was 346.78 ng/g. PAHs are mainly composed of the 2- and 3-ring PAHs, with naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), benzo(g,h, i) perylene (Dib), fluoranthene (Flua), and indeno (1,2,3-c,d) pyrene (Ind) as the dominant constituents. The principal component analysis combined with multiple linear regression showed that petroleum combustion and biomass/coal combustion have contributed 52.78% and 40.53%, respectively, to the PAHs in intertidal sediments of Pearl River Estuary. The occurrence of adverse biological effects as a result of PAH contamination in the intertidal sediments of Pearl River Estuary has increased by 8% based on the mean value of the probable effect quotient.

The presence of microplastics (MPs) in the marine environment is a concerning topic due to the ecotoxicological effects and possible seafood contamination. Data is needed to evaluate human exposure and assess risks, in the context of a healthy and beneficial seafood consumption. While microplastic ingestion by wild fish has been reported since the early 70‘s, farmed fish are rarely investigated. Here, for the first time the presence of microplastics in fish cultivated in the coastal water of Tenerife (Canary Island, Spain) was evaluated. From 83 examined individuals, 65% displayed microplastics in their gastrointestinal tracts, with averages between 0.6 ± 0.8 (SD) and 2.7 ± 1.85 (SD) particles per fish. The total number of microplastics detected was 119. Fibres (81%) and fragments (12%) were the predominant shapes. FTIR analysis showed that fibres were mostly composed by Cellulose (55%) and Nylon (27%), whereas fragments by PE (25%) and PP (25%).

This study analyzed trace elements (As, Ba, Cd, Cu, Fe, Mn, Pb, Zn) and stable isotopes of carbon and nitrogen in egg yolk samples of female green turtles that nested in Rocas Atoll, Brazil, in 2017 and 2018. The trace elements concentration varied between years, with higher concentrations in 2017, suggesting that the nesting groups come from different foraging sites. The isotopic data indicated high overlap between years (73%), leading to an ambiguous interpretation on the turtles' foraging site. The Normalized Total Load presented a low association (0.01 < R² < 0.41) with the stable isotopes. The Normalized Total Load that represents the trace element load in egg yolk is a holistic approach that can be applied elsewhere to predict ecotoxicology pathways in any animal species. We recommend a continuous monitoring to verify how the trace elements load behave in the nesting green turtles on Rocas Atoll.

To improve our knowledge of the factors regulating Phaeocystis globosa colony formation, the effects of the diatom Ditylum brightwellii on P. globosa colony development were investigated using co-culture and cell-free filtrate approaches. The co-culture experiments showed the moderate abundance of D. brightwellii significantly increased the number and size of colonies, whereas a dramatically decreased effect from high abundance of D. brightwellii. The low abundance of D. brightwellii promoted early formation of P. globosa colony. The cell-free filtrate experiments indicated that culture-filtrates from the exponential phase of D. brightwellii were stimulatory for P. globosa colony formation with more and bigger colonies formed, whereas an inhibitory effect from its senescence phase filtrates. D. brightwellii may influence P. globosa colony formation by regulating the growth of P. globosa solitary cells. Our results suggest that D. brightwellii influences P. globosa colony development, but its effects vary according to its concentrations and growth phases.

Marine oil spills pose a significant threat to ocean and coastal ecosystems. In addition to costs incurred by response activities, an economic burden could be experienced by stakeholders dependent on coastal resources. Decision support tools for oil spill response (OSR-DSTs) have been playing an important role during oil spill response operations. This paper aims to provide an insight into the status of research on OSR-DSTs and identify future directions. Specifically, a systematic review is conducted including an examination of the advantages and limitations of currently applied and emerging decision support techniques for oil spill response. In response to elevated environmental concerns for protecting the polar ecosystem, the review includes a discussion on the use of OSR-DSTs in cold regions. Based on the analysis of information acquired, recommendations for future work on the development of OSR-DSTs to support the selection and implementation of spill response options are presented.