We investigated the occurrence, origin, and potential ecological risk of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCBs) and organochlorine pesticides (OCPs) in 27 surface water samples collected from a highly anthropized and industrialized area in the Gulf of Gabès (Tunisia, Southern Mediterranean Sea) in October–November 2017. The results demonstrated a wide range of concentrations (ng L⁻¹) with the following decreasing order: Ʃ16 PAHs (17.6–71.2) > Ʃ20 PCBs (2.9–33.7) > Ʃ6 DDTs (1.1–12.1) > Ʃ4 HCHs (1.1–14.8). Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, with a predominance of petrogenic sources. PCB compositions showed distinct contamination signatures for tetra- to hepta-chlorinated PCBs, characteristic of contamination by commercial (Aroclor) PCB mixtures. The dominant OCP congeners were γ-HCH, 2,4′-DDD and 2,4′-DDE, reflecting past use of Lindane and DDTs in the study area. Agricultural, industrial and domestic activities, as well as atmospheric transport are identified as potential sources of PAHs, PCBs and OCPs in surface waters of the Gulf of Gabès. Toxic equivalents (TEQs) suggested a low carcinogenic potential for PAHs in seawater samples (mean of 0.14 ng TEQ L⁻¹). Evaluation of risk coefficients revealed low risk for PAHs and PCBs, and moderate to severe risk for OCPs.

The quantification of macroplastic fluxes transferred by rivers toward the pelagic environment requires a better understanding of macrodebris transfer processes in estuarine environments. Following the strategy adopted in the Seine estuary, this study aims to characterize macroplastic trajectories in the Loire estuary. Between January 2020 and July 2021, 35 trajectories were monitored using plastic bottles equipped with GPS-trackers. With total travelled distances between 100 m and 103.6 km, trajectories show great spatiotemporal variability. The various forcing factors (macroplastic buoyancy, estuaries tidal and hydrometeorological conditions, geomorphology and vegetation) lead to chaotic trajectories, preventing accurate predictions in macroplastic transfer and storage/remobilization dynamics. In the Loire estuary like in the Seine one, no tracked bottle reached the Atlantic Ocean. It confirms that macrotidal estuaries under temperate climates constitute accumulation zones and slow pathways for macroplastics, but raises question on the real fluxes transferred from continental areas to oceans.

Microplastics (MPs) are widely present in global oceans, and can pose a threat to marine organisms. This study examined the abundance and characteristics of MPs in seawater, sediment, and organism samples collected from Hangzhou Bay. Abundance of MPs in seawater (n = 26) and sediment (n = 26) were 0.77–9.6 items/m³ and 44–208 items/kg dw, respectively. Size of MPs in sediment (mean 2.5 mm, range 0.21–5.3 mm) was significantly (p < 0.05) larger than that in seawater (1.1 mm, 0.13–4.9 mm). Fiber was consistently the predominant shape of MPs in seawater and sediment. The major polymer composition of MPs was polyethylene (PE; mean 47 %) in seawater, but textile cellulose (60 %) was the main polymer type of MPs in sediment. Average abundance of MPs in marine organisms (n = 388) ranged from 0.064 (zooplankton) to 2.9 (Harpodon nehereus) items/ind, with the mean size of 0.19–1.4 mm. MP abundance in marine organisms was not significantly correlated with their trophic level. Fiber was always the predominant shape of MPs in different marine organisms, contributing mean 67 (fish)–93 % (zooplankton) of total MPs. MPs in crustacean (mean 58 %), shellfish (64 %), and cephalopod (29 %) were dominated by textile cellulose. Whereas, PE (mean 44 %) and polypropylene (43 %) were the major polymer compositions of MPs in fish and zooplankton, respectively. To our knowledge, this is the most comprehensive study investigating the occurrence of MPs in environmental matrixes from Hangzhou Bay, which contributes to the better understanding of environmental behaviors of MPs in estuarine sea environment.

The potential release of metals, especially copper (Cu) during mining of seafloor massive sulphides (SMS), represents a potential toxicological threat to cold-water coral (CWC) habitats. Herein, we evaluated for the first time the response of the whip coral Viminella flagellum to short-term acute Cu exposure. Nubbins of V. flagellum were exposed to Cu concentrations of 0 (control); 60; 150; 250; 450 and 600 μg/L for 96 h. After exposure, V. flagellum nubbins were transferred to a continuous flow-through aquarium and feed once a day for 3 weeks. No immediate mortality was detected during the short-term Cu exposure. However, a delayed mortality, which was concentration dependent was observed. The first signs of tissue loss occurred after 1 week of recovery in non-contaminated conditions in V. flagellum nubbins previously exposed to Cu concentrations of 60 and 150 μg/L followed by nubbins exposed to Cu concentrations of 250, 450 μg/L after 2 weeks and 600 μg/L after 3 weeks. A delayed mortality impact should be considered in future Cu tolerance experiments and scenarios of deep-sea mining exploitation.

Assessing toxic metals (TMs) contamination and phytoremediation potentiality in coastal mangrove lagoons is needed for applying sustainable management of this ecosystem. Consequently, here we determined the pseudo-total content of TMs in the sediments and mangrove plants (leaves, stems, aerial roots, and fine roots) collected from Al-Shuaiba, Yanbu, and Jeddah lagoons, along the coast of Red Sea. The contamination degree was assessed using different indices and the potentiality of mangroves for TMs phytoremediation was determined. The average total metals content (mg kg⁻¹) in the sediments ranged from 1806 to 9580 for Fe, 65 to 195 for Mn, 3.9 to 25.9 for Cu, 5.5 to 16.4 for Zn, 0.09 to 0.42 for Cd, 8.9 to 20.9 for Cr, 32.8 to 37.9 for Ni, and from 0.69 to 6.7 for Pb. The sediments of Yanbu site contained the highest content of all metals (except for Cu), while Al-Shuaiba sediments contained the lowest values. The contamination factor (CF) showed that the sediments of Yanbu and Jeddah suffer from high and moderate contamination degree of Cd. These sites suffer from moderate grade of Ni contamination. The CF values of Fe, Mn, Cr, Cu, and Zn in the three sites were lower than unity, which show low contamination degree. Iron, Cr, Cu, Ni, Pb, and Zn were concentrated in the fine roots, while Cd was concentrated in the stems. Mangrove plants at Yanbu site contained significantly higher content of all metals than the grown plants in Jeddah and Al-Shuaiba sites, which can be explained by the high metal content in the sediments and the anthropogenic metal sources such as the petrochemical industries, and the industrial and municipal wastewater discharged into this site. Sediment-to-plant transfer coefficients values were higher than unity, which indicate that the mangrove plants have the potential to accumulate the metals. The results highlight a potential risk at Yanbu and Jeddah sites and may help for applying sustainable trials for phyto-management of these lagoons.

Mercury (Hg) is globally-distributed, with severe toxic effects on wildlife. Methylmercury biomagnifies within food webs, so long-lived, top predators such as seabirds are prone to high mercury concentrations. We synthesized historical and contemporary data on mercury concentrations in seabirds from the North Atlantic. We collected 614 values determined from 39 species and 115 locations, ranging from 1895 to 1940 and from 1970 to 2020. Highest blood-equivalent Hg values were in Phalacrocoracidae. For the same species/tissue/collection site, blood-equivalent values were lower during pre-1940 than post-1970 period. In almost 5 % of post-1970 values, mean blood-equivalent Hg concentrations were above those considered to pose severe risks of adverse effects, and 21 % were above the high-risk effect. We found an imbalance in sample effort and did not find Hg values for many species. We argue that stronger, trans-Atlantic Hg monitoring schemes are required to coordinate research and better compare trends across a wide scale.

We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.

The outbreak of the COVID-19 pandemic has brought enormous challenges to the global marine environment. Various responses to the COVID-19 pandemic have led to increased marine pollution. Has the COVID-19 pandemic affected marine pollution research? This work comprehensively reviewed marine pollution publications in the Web of Science database before and during the COVID-19 pandemic. Results show that the COVID-19 outbreak has influenced the marine pollution research by: (i) increasing the number of publications; (ii) reshaping different countries' roles in marine pollution research; (iii) altering the hotspots of marine pollution research. The ranking of countries with high productivity in the marine pollution research field changed, and developed economies are the dominant players both before and after the outbreak of the COVID-19 pandemic in this field. Other high-productivity countries, with the exception of China, have higher international cooperation rates in marine pollution research than those before the pandemic. Microplastic pollution has been the biggest challenge of marine pollution and has been aexplored in greater depth during the COVID-19 pandemic. Furthermore, the mining results of marine pollution publications show the mitigation of plastic pollution in the marine environment remains the main content requires future research. Finally, this paper puts forward corresponding suggestions for the reference of researchers and practitioners to improve the global ability to respond to the challenges posed by the pandemic to the marine environment.

Ballast water is a primary vector for the global transfer of non-indigenous species, which threaten the balance of aquatic ecosystems. The second-generation high-throughput sequencing (HTS) and culture method (by the first-generation sequencing technology) were used to explore pathogens in ballast water from international ships on the routes of China-Australia (AU), China-Europe (E) and China-America (AM). No significant differences in dominant bacteria among ballast water samples from different routes. Thirty-four pathogens were detected in all samples by HTS, including Acinetobacter lwoffii, Brevundimonas vesicular and Pseudomonas sp., etc., while nine pathogens were detected by culture, including Pseudoalteromonas piscicida, Rhodococcus erythropolis and Vibrio alginolyticus, etc. All ballast water carried a potential bacteriological risk to Yangshan Port. The abundance of pathogens was significant affected by holding time, temperature, salinity and NH₄. Detection of pathogens as much as possible through different technologies is desirable, more pathogens could provide beneficial information for enhancing ballast water management.

Distribution of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in molluscan and echinoderm species collected from Kerala and Gulf of Mannar in Southern India is presented. Atomic absorption spectrometry was used to determine metal concentrations. Concentrations of metals showed a descending order of Zn > Cu > Pb > Cd > Cr. Zn and Cu might have originated from both natural and man-made sources. However, Cd, Cr, and Pb could have strong anthropogenic influences such as harbour activities and untreated industrial and agricultural runoff. Bioaccumulation factor (BAF) value of Cd in two edible bivalves from Munambam is slightly greater than one. Regular consumption of Cd-loaded shellfish can cause serious health hazards and concerns to humans. BAF results showed that Zn, Cu, Pb, and Cd were more bioaccumulated and beyond the threshold limits in certain species. It is evident that consumption of shellfish from the Kerala coastal waters may have adverse health impacts to the consumers.