Anthropogenic marine litters or microplastics (MPs) accumulation in marine organisms is an emerging environmental threat. In this background, the gastrointestinal tract of Coilia dussumieri (n = 150) was studied in the samples collected from the fishing grounds of the north east coast of Arabian Sea through experimental fishing. Out of the total 150 specimens collected, all showed the incidence of microplastic particulates in the guts. The average abundance of MPs was found to be 6.98 ± 2.73 items/individual whereas gastrointestinal tract recorded with an average number of 28.84 ± 10.13 MPs/g in the gut material. The dominant MPs were found in the size range of 100–250 μm and of fibers type mostly blue in color. The prevalence of MPs in Coilia dussumieri is a matter of serious concern due to its ecological consequences due to trophic transfer in the connected food chains and probable threats to the health of human beings consuming the fish.

Negative human actions on seagrasses affect habitat condition and its associated fauna. Epiphytic hydroid's assemblage response to seagrass condition, water quality, and human impacts was evaluated in two bays of the Sabana-Camagüey Ecosystem of Cuba, using the presence of contamination, causeways, and trawling fishing as impact level proxies to the seagrass meadows. Thirty-eight species composed the hydroid's assemblage including five new records. Symmetroscyphus intermedius was the most abundant species and sensitive to indicators of the seagrass condition. Dynamena disticha and Gastroblasta sp. were sensitive to water quality predictors. Obelia bidentata was exclusive to the most impacted sites. Species richness and abundance were low in impacted sites and were highly affected by fishing trawling and causeways construction. Salinity, depth, NO2, pH, SSV, macroalgae cover, shoot density, and wet weight of Thalassia testudinum were the best predictors for hydroid's assemblages. Results suggest epiphytic hydroids on tropical seagrass meadows as sentinel organisms.

PURPOSE OF REVIEW: PM₂.₅ satellite remote sensing is the most powerful way to acquire the PM₂.₅ distribution and variation at a large scale with high resolution. Thus, PM₂.₅ remote sensing methods have been widely developed and applied in multiple environmentally related research areas in recent decades. Hence, the purpose of this review is to summarize these methods, required input data and main applications of PM₂.₅ and its remote sensing components. RECENT FINDINGS: In general, two-step methods have been used for estimating PM₂.₅, which first retrieves the aerosol optical depth (AOD) and estimates PM₂.₅ from the AOD with other supplemental data containing the temporal or spatial variation impact on PM₂.₅ or data correlated with PM₂.₅ variation by different AOD-PM₂.₅ models. The AOD-PM₂.₅ models have been developed by using different methods, including empirical-statistical models (single or combined statistical models and big data-based machine learning methods), CTM-based models and semi-empirical/physical models. Current research can provide high-resolution (e.g. daily variations at 1 km and hourly variations at ~1 km) PM₂.₅ products, which have been widely used in air pollution management, health impact assessments, numerical data assimilation and climate impact analyses. This review summarizes the current research on method development, application, achievement and remaining challenges in remote sensing of PM₂.₅ and its components, which are essential for further improvement of the methods and accuracy of PM₂.₅ remote sensing and are likely applicable to other PM₂.₅ component remote sensing methods in the future.

Major sources of pollution from shipping to marine environments are antifouling paint residues and discharges of bilge, black, grey and ballast water and scrubber discharge water. The dispersion of copper, zinc, naphthalene, pyrene, and dibromochloromethane have been studied using the Ship Traffic Emission Assessment Model, the General Estuarine Transport Model, and the Eulerian tracer transport model in the Baltic Sea in 2012. Annual loads of the contaminants ranged from 10⁻² tons for pyrene to 100 s of tons for copper. The dispersion of the contaminants is determined by the surface kinetic energy and vertical stratification at the location of the discharge. The elevated concentration of the contaminants at the surface persists for about two-days and the contaminants are dispersed over the spatial scale of 10-60 km. The Danish Sounds, the southwestern Baltic Sea and the Gulf of Finland are under the heaviest pressure of shipborne contaminants in the Baltic Sea.

Ingestion of plastic pollution by pelagic seabirds is well-documented globally, but increasingly, researchers are investigating plastic ingestion in generalist predators and scavengers like gulls. We studied the gut contents of two sympatric gull species, American herring gulls (Larus smithsoniansus) and great black-backed gulls (L. marinus), collected year-round as part of “kill-to-scare” measures at the regional sanitary landfill in St. John's, Newfoundland and Labrador, Canada, to compare ingested anthropogenic debris, trophic position and diet breadth through the year. Although great black-backed gulls fed at a higher trophic level, frequency of occurrence of plastic ingestion was similar to American herring gulls, and varied little through the year. Diet breadth (isotopic niche size) was similar between species, but American herring gulls fed at a lower trophic level during winter, perhaps indicating a change in their reliance on anthropogenic food subsidies throughout their annual cycle.

The occurrence and spatial distribution of bisphenol A (BPA) and analogues bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) were investigated in microplastic on 11 beaches in Hong Kong. At 10 sites, BPA was the only detected chemical with concentrations ranged from 82.4–989 ng g⁻¹ microplastic. BPA, BPB and BPS co-occurred at only one site, where it is located close proximity to the outfall of a sewage treatment plant. There was no significant spatial difference of BPA concentrations in microplastic when all the sites were considered, indicating that some remote and presumably cleaner beaches have been contaminated. PE, PP and PS (represented >90% of total polymers) were the most dominated polymers, but there was no correlation between polymer types and BPA concentrations. No evidence was found that the BPA and its analogues accumulate on microplastic since the concentrations were comparable to those found in the sediment.

Algae-dominance in seagrass beds has been well recognized, however, the competitive relationship between seagrass and macroalgae along land-sea gradients and their ecological effects has received little attention. In this study, a field survey was conducted at the Yellow River Estuary to investigate the effects of macroalgal proliferation on seagrass and macrobenthic invertebrate communities. Our results suggested that strong competitive interaction existed between the two primary producers, and the positive or negative effects of macroalgae on seagrass growth varied along land-sea gradient. Furthermore, the dominant controlling factors on the biomass, density and diversity of macrobenthic invertebrate communities were found to vary accordingly, i.e., from features of the primary producers in the nearshore where macroalgae suppressed seagrass growth to hydrodynamic disturbance in the offshore where macroalgae facilitated seagrass growth. Our study emphasizes the importance to integrate interspecific competition into ecosystem-based management of seagrass ecosystem, and provides references for additional ecological indicators.

Following the Deepwater Horizon oil spill of 2010, large amounts of biodegraded oil (petrocarbon) sank to the seafloor. Our objectives were to 1) determine post-spill isotopic values as the sediments approached a new baseline and 2) track the recovery of affected sediments. Sediment organic carbon δ¹³C and Δ¹⁴C reached a post-spill baseline averaging −21.2 ± 0.9‰ (n = 129) and −220 ± 66‰ (n = 95). Spatial variations in seafloor organic carbon baseline isotopic values, ¹³C and ¹⁴C, were influenced by river discharge and hydrocarbon seepage, respectively. Inverse Distance Weighting of surface sediment Δ¹⁴C values away from seep sites showed a 50% decrease in the total mass of petrocarbon, from 2010 to 2014. We estimated a rate of loss of −2 × 10⁹ g of petrocarbon-C/year, 2–11% of the degradation rates in surface slicks. Despite the observed recovery in sediments, lingering residual material in the surface sediments was evident seven years following the blowout.

The distribution of aliphatic hydrocarbons in three sediment cores from Brunei Bay was investigated in order to understand their sources and the biogeochemical processes of these hydrocarbons. The total concentrations of C₁₅ to C₃₇n-alkanes ranged from 0.70 to 16.5 μg g⁻¹. Traces of hopanes with C₂₉–C₃₁ carbon homologs were detected in the study area. The carbon preference index (CPI₁₅–₃₇) ranged from 1.23 to 3.42 coupled with the natural n-alkane ratio (NAR₁₉–₃₂) ratios (1.52 to 5.34), and the presence of unresolved complex mixtures and hopanes, suggested slight contamination by anthropogenic hydrocarbons, presumably derived from activities along the coasts. The presence of C₂₇ trisnorhopene and diploptene, as well as their association with long-chain and short-chain n-alkanes, revealed a depositional environment of organic matter in the sediment cores.

The level of heavy metal contamination and ecological risk, as well as the sources of contamination, of 35 sediments from the Al-Uqair coast, Saudi Arabia, were determined via inductively coupled plasma mass spectrometry. The average concentrations (dry weight) were highest for Fe (8091.51 μg/g), followed by Al (1816.60), As (14.99), Cu (11.27), Zn (7.62), Pb (3.88), Mn (3.82), Cr (3.67), Hg (2.40), Se (0.68), Ni (0.57), Cd (0.07), and Sb (0.06). The average TOC and heavy metal values, except Hg and As, were much lower than many coastal sediments elsewhere. The sediments had moderate-to-high heavy metal pollution, especially with high Hg contamination and substantial Se and As enrichment. Moreover, the sediments were at a high ecological risk for Hg, As, and Cd, moderate risk for Cu, and no-to-low risk for Pb, Zn, Ni, Cr, and Sb. Hg, Cd, Cr, As, Se, Cu, Sb, Pb, Ni, and Zn were likely from lithogenic and anthropogenic sources, including rock weathering, agricultural runoff, and untreated domestic sewage. However, Al, Fe, and Mn were naturally derived.