The release of oil and gas at Mississippi Canyon Block 20 into the Gulf of Mexico has vexed response officials since 2004 when a regional seafloor failure toppled the Taylor Energy Company platform. Despite the completion of nine intervention wells, releases continue from the seafloor, mostly captured by a recently installed containment system. Toward informing resolution, this work applies chemical forensic and statistical analyses to surface sheens, sediments, and reservoir oil samples. Our results indicate sheens are chemically heterogeneous, contain remnant synthetic hydrocarbons likely discharged from well interventions prior to 2012, and require mixing of multiple chemically-distinct oil groups to explain observed variability in diagnostic ratios. Given the respite and opportunity afforded by containment we suggest leveraging ongoing collection activities to assess release dynamics, as well as engaging the National Academies of Science, Engineering, and Medicine, to evaluate potential solutions, associated risks, and to consider policy ramifications.

The 2010 Deepwater Horizon (DwH) oil spill in the Gulf of Mexico discharged ~3.19 million barrels of oil into Gulf waters, making it one of the largest marine disasters in history in terms of volume. We report on the results of a study to assess oil impacts to coastal fishes and invertebrates. Using two-decades of fisheries-independent data in coastal Alabama and Mississippi, we document variability following both natural and anthropogenic disturbances from two periods pre-DwH (1997–2001 and 2007–2009), one intra-spill period for acute DwH effects (2010–2012) and one period post-spill for chronic, longer-term impacts (2014–2017). Results indicated significant changes to community structure, relative abundance, and diversity in the intra-spill period. Causation for changes is confounded by variables such as behavioral emigration, altered freshwater inflow, death of consumers, and the mandated fishery closure. Results highlight the need for long-term, comprehensive monitoring/observing systems to provide adequate background for assessing future disturbances.

Climate Change solutions include CO₂ extraction from atmosphere and water with burial by living habitats in sediment/soil. Nowhere on the planet are blue carbon plants which carry out massive carbon extraction and permanent burial more intensely concentrated than in SE Asia. For the first time we make a national and total inventory of data to date for “blue carbon” buried from mangroves and seagrass and delineate the constraints. For an area across Southeast Asia of approximately 12,000,000 km², supporting mangrove forests (5,116,032 ha) and seagrass meadows (6,744,529 ha), we analyzed the region's current blue carbon stocks. This estimate was achieved by integrating the sum of estuarine in situ carbon stock measurements with the extent of mangroves and seagrass across each nation, then summed for the region. We found that mangroves ecosystems regionally supported the greater amount of organic carbon (3095.19Tg Cₒᵣg in 1st meter) over that of seagrass (1683.97 Tg Cₒᵣg in 1st meter), with corresponding stock densities ranging from 15 to 2205 Mg ha⁻¹ and 31.3 to 2450 Mg ha⁻¹ respectively, a likely underestimate for entire carbon including sediment depths. The largest carbon stocks are found within Indonesia, followed by the Philippines, Papua New Guinea, Myanmar, Malaysia, Thailand, Tropical China, Viet-Nam, and Cambodia. Compared to the blue carbon hotspot of tropical/subtropical Gulf of Mexico's total carbon stock (480.48 Tg Corg), Southeast Asia's greater mangrove–seagrass stock density appears a more intense Blue Carbon hotspot (4778.66 Tg Corg). All regional Southeast Asian nation states should assist in superior preservation and habitat restoration plus similar measures in the USA & Mexico for the Gulf of Mexico, as apparently these form two of the largest tropical carbon sinks within coastal waters. We hypothesize it is SE Asia's regionally unique oceanic–geologic conditions, placed squarely within the tropics, which are largely responsible for this blue carbon hotspot, that is, consistently high ambient light levels and year-long warm temperatures, together with consistently strong inflow of dissolved carbon dioxide and upwelling of nutrients across the shallow geological plates.

As the largest inland sea of China, the Bohai Sea has confronted significant environmental changes in recent decades, and a shift of phytoplankton community from diatoms to dinoflagellates was observed by microscopic method in previous studies. However, the counting of some small-sized non-diatoms (e.g., flagellates and cyanobacteria) have long been neglected due to the limitation of this method. In this study, we measured the phytoplankton community structure and abundance in the central Bohai Sea in summer and autumn of 2015 by employing both microscopic method and high-performance liquid chromatography (HPLC) pigments – CHEMTAX analysis. The results of microscopic counting showed that the phytoplankton community was characterized by diatoms, dinoflagellates, and chrysophytes, which contained a total of 107 species. Dinoflagellates and diatoms co-dominated in summer while the latter became the dominant group in autumn. Compared with microscopic counting, CHEMTAX analysis allowed identification of a larger number of phytoplankton groups (including 8 phyla). The results of CHEMTAX analysis showed that besides diatoms and dinoflagellates, the small-sized non-diatoms (i.e., flagellates and cyanobacteria) also played an important role. Diatoms and cyanobacteria dominated the total Chl a (contributing 32.5% and 17.1%, respectively), followed by cryptophytes, dinoflagellates, and prasinophytes in the summer. A short-term summer to autumn variability of phytoplankton abundance and community was observed. Temperature and nutrient availability affected the succession of the phytoplankton community from diatoms and non-diatoms co-dominance in the summer to absolute diatoms dominance in the autumn. A direct comparison of algal cell abundance and CHEMTAX biomass showed that a significant positive correlation was observed only for dinoflagellates (P < 0.01) in the autumn. Our work provides some basic information on the dynamics of small-sized flagellates and cyanobacteria in this area, and also suggests that a combination of both the methods is needed in future investigations to better understand the current status as well as the future changes of phytoplankton community.

The diversity, distribution, and mechanisms of bacterial speciation of Vibrio species belonging to Harveyi clade are an important global research interests due to their pathogenic activity in coastal environments. Luminous bacteria are also known to act as environmental indicators in coastal waters. This study demonstrates that luminous bacteria belonging to harveyi clade are predominant in seawater, sediment, surfaces of marine animals and plants, and light organs of leiognathid fishes. Molecular phylogenies for eighteen morphologically distinct and potentially luminous strains chosen out of 57 isolated luminous bacteria. Sequence analysis of luxA gene as a molecular marker identified luminous bacteria belonging to Harveyi clade, Photobacterium clade, and Anguillarum clade distinctly. Rich biodiversity and distribution of luminous bacterial species (30% to 40%) was found in association with coral reef samples of south Andaman. This study confirms and reveals the evidence on predominant association of Harveyi clade luminous vibrio's in coastal waters of south Andaman.

Marine litter levels were measured in the stomach contents, hepatopancreas, and gonad tissues of crustacea decapod (Callinectes sapidus Rathbun, 1896; n = 6), a widespread alien species affecting the Lesina lagoon. Results highlight a mean of 2.5 (SD = 1.6) items/animal and indicate the presence of metals fragments (13%) and plastics (13% PE; 6.7% PET) in the stomach contents of collected individuals. No microplastic particles were detected in the hepatopancreas or in muscle tissue, while microplastic fibres (nylon, rayon, polyester) were found present in female specimen gonads. The presence of synthetic fibres in the investigated species reflects the relative contamination level in this habitat type and suggests that the blue crab could be considered a model organism for evaluating the contamination status of the study area.

The concentrations of dissolved rare earth elements (REEs) and trace elements (Al, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and Pb) were measured along the Nakdong River Estuary. In general, REE concentrations presented negative correlations with salinity, except for the sampling sites close to the wastewater treatment plant (WWTP), where the concentrations were approximately two orders of magnitude higher. In this study, we attempted to utilize REEs as tracers for river versus WWTP sources of trace elements. The main sources of trace elements can be attributed as follows: the seawater for Mo and Cd, the seawater and WWTP for V, the river and WWTP for Ni and Cu, and the WWTP for Al, Mn, Fe, Co, Zn, and Pb. Our results suggest that REEs can serve as powerful tracers for WWTP sources, particularly in coastal waters where various trace element sources are present.

Underwater noise pollution from impulsive sources (e.g. explosions, seismic airguns, percussive pile driving) can affect marine fauna through mortality, physical injury, auditory damage, physiological stress, acoustic masking, and behavioural responses. Given the potential for large-scale impact on marine ecosystems, some countries are now monitoring impulsive noise activity, coordinated internationally through Regional Seas Conventions. Here, we assess impulsive noise activity in the Northeast Atlantic reported during 2015–2017 to the first international impulsive noise register (INR), established in 2016 under the OSPAR Convention. Seismic airgun surveys were the dominant noise source (67%-83% of annual activity) and declined by 38% during 2015–2017. Reported pile driving activity increased 46%. Explosions and sonar/acoustic deterrent devices both had overall increases in reported activity. Some increases were attributable to more comprehensive reporting in later years. We discuss utilising the INR for risk assessment, target setting, and forward planning, and the implementation of similar systems in other regions.

The pollution of continental shelf sea sediments has always been an important issue for scientists because it can directly affect marine life and marine ecology. Thus, we carried out detailed studies of environmental magnetism and heavy metals in 145 surface sediment samples from the area southeast of the Zhoushan Islands in the East China Sea. The magnetic minerals in the sediments are mainly magnetite with a small amount of goethite and hematite. The magnetic mineral particles are mainly pseudosingle domain and contain a certain amount of superparamagnetic particles. The distribution of the magnetic mineral content shows a gradual decreasing trend from land to sea, which is closely related to the sediment transport pattern. The anhysteretic remanent magnetization (χARM) and χARM ratio to magnetic susceptibilities (χARM/χ) were more sensitive than other indexes to sediment pollution and could be used as indicators for environmental pollution in the nearshore area. Additionally, a correlation analysis with the major elements showed that the χARM ratio to saturation isothermal remanence (χARM/SIRM) can well explain the sources of terrigenous sediment. Therefore, the environmental magnetic parameters in the continental shelf area can be used as a precursor for geochemical research and provide data support for further research.

The level of contamination of selected priority pollutants consisting of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) were investigated from the tissues of stranded green sea turtles, Chelonia mydas, from the Gulf of Oman coast of the United Arab Emirates. Tissue samples - muscle and liver - were collected from 22 stranded green sea turtles from the coasts of Kalba and Khorfakkan from 2016 to 2018. Overall, we detected persistent organic pollutants (POPs) in 77% of the turtles. PAH's were the most frequently detected followed by high concentrations of OCP's (71% and 25% of the turtles, respectively). PCB's were not detected in any samples. Factors such as specimen size, mass of debris ingested and toxin hydrophobicity were not important factors affecting the concentrations of these compounds.