We developed a dimethylsulfide (DMS) module coupled to an ecological dynamics model studying the annual DMS cycle of the Yellow and East China seas (YECS). The model results showed that surface DMS concentrations ([DMS]) peaked in August along the coast, and there exhibited several DMS peaks offshore annually. In addition, surface [DMS] were higher in the Yellow Sea than that in the East China Sea. The annual mean surface [DMS] of the YECS reached to 4.55 nmol/L, and oceanic DMS emissions from this sea area was 6.78 μmol/(m² day). Several sensitivity experiments demonstrated that phytoplankton community and sea water temperature exerted crucial effects on seasonal variations of surface [DMS]; and phytoplankton community or temperature changed the timing of surface DMS peak while photolysis affected the magnitude of [DMS]. Moreover, the effect size of phytoplankton community or water temperature varied spatially.

The quantity of floating plastic debris (FPD) is continuously being increased in the oceans. To assess their size, structure, and composition along the eastern Arabian Sea (EAS), FPD samples were collected by using a surface plankton net. The microplastic size fraction (0.5–5 mm) was the most prevalent accounting for >50% of the total, followed by mesoplastics (5–25 mm; ~40%) and macroplastics (>25 mm; ~10%). The collected FPDs were categorized into five different types and eight colours. Attenuated Total Reflectance-Fourier Transform Infrared Spectrometry (ATR-FTIR) analysis of the plastics revealed that polypropylene, polyethylene, and nylon were the most dominant polymers, and these comprised mostly of fibre/fishing line. The abundance of FPD in the EAS (0.013 ± 0.012 no.s/m³) was found to be very low compared to elsewhere. The prevalent microplastics presence in the oceans might have occurred mainly by the degradation of larger items. It increases bioavailability, and hence, is a risk to marine ecosystems.

Microplastic (MPs) pollution has been recognized as a serious threat to marine environment with the growing use of plastics. There is no sufficient data on the extent and characteristics of MPs pollution in the beach sediments and sand in the Atlantic Ocean. The coastal area is one of the main tourist zones in Aveiro in Portugal, thus, impacted by both tourism and maritime traffic, which are major sources of MPs. Considering this issue, 33 sediment samples were collected from the Praia da Barra beach in Aveiro. This pilot study showed that large quantities of MPs are accumulated on this beach with a median concentration of 100 MP kg-1 (15–320 MP kg-1), that is dominated by polyethylene (30%), polypropylene (27%), polystyrene (18%), nylon (12%), and polyester (6%). Size <1 mm constituted 99.5% of particles, mostly of transparent or black colors, with highest concentrations closest to the water line.

Ocean acidification and hypoxia have become increasingly severe in coastal areas, and their co-occurrence poses emerging threats to coastal ecosystems. Here, we investigated the combined effects of ocean acidification and hypoxia on the reproductive capacity of the thick-shelled mussel Mytilus coruscus. Our results demonstrated low pH but not low oxygen induced decreased gonadosomatic index (GSI) in mussels. Male mussels had a lower level of sex steroids (estradiol, testosterone, and progesterone) when kept at low pH. Expression of genes related to reproduction were also impacted by low pH with a downregulation of genes involved in gonad development in males (β-catenin and Wnt-7b involved in males) and an upregulation of testosterone synthesis inhibition-related gene (Wnt-4) in females. Overall, our results suggest that ocean acidification has an impact on the gonadal development through an alternation of gene expression and level of steroids while hypoxia had no significant effect.

We surveyed 41 sites to provide an updated baseline of Hong Kong coral communities. Five community types were identified, among them the most common one inhabited oceanic waters and dominated by both massive and upward-plating corals. The 41 sites had 2.1–⁠79% coral cover; among them 21 in the eastern waters had >40% coral cover. Corals in several sites showed signs of external bioerosion or bleaching-induced damage. Sites in the southern waters had low coral cover. Both coral cover and generic richness correlated negatively with several water quality parameters including total inorganic nitrogen concentration and turbidity, indicating the development of Hong Kong's coral communities is constrained by water quality parameters. Management actions are proposed to reduce bioerosion, and to monitor sites affected by bleaching.

Here we provide a first assessment of microplastics (MPs) in stomach contents of 15 common dolphins (Delphinus delphis) from both single and mass stranding events along the New Zealand coast between 2019 and 2020. MPs were observed in all examined individuals, with an average of 7.8 pieces per stomach. Most MPs were fragments (77%, n = 90) as opposed to fibres (23%, n = 27), with translucent/clear (46%) the most prevalent colour. Fourier transform infrared (FTIR) spectroscopy revealed polyethylene terephthalate (65%) as the most predominant polymer in fibres, whereas polypropylene (31%) and acrylonitrile butadiene styrene (20%) were more frequently recorded as fragments. Mean fragment and fibre size was 584 μm and 1567 μm, respectively. No correlation between total number of MPs and biological parameters (total body length, age, sexual maturity, axillary girth, or blubber thickness) was observed, with similar levels of MPs observed between each of the mass stranding events. Considering MPs are being increasingly linked to a wide range of deleterious effects across taxa, these findings in a typically pelagic marine sentinel species warrants further investigation.

Several studies have estimated global inputs of plastic into the environment, relying on national statistics and modeling approaches. However, these estimates exhibit uncertainty driven by limited primary municipal solid waste management data. We compare mismanaged plastic estimates from three global studies (Jambeck et al. (2015), Lebreton and Andrady (2019), and Borrelle et al. (2020)), finding significant differences. Specifically, 58 countries show at least a 25 percentage point difference in estimated mismanagement rates, 27 countries show at least a 50 percentage point difference, and 9 countries show at least a 75 percentage point difference. Further, several top plastic generators exhibit large discrepancies in mismanagement estimates, including China, Russia, and Indonesia. The limitations of global plastic pollution estimates are well-known in the scientific community, and some variation is expected. However, these discrepancies limit policy design and mitigation. Thus, municipal, national, and international monitoring of plastic management and pollution must be improved.

With increasing maritime activities in the proximity of coral reefs, a growing number of manmade structures are becoming available for coral colonisation. Yet, little is known about the sessile community composition of such artificial reefs in comparison with that of natural coral reefs. Here, we compared the diversity of corals and their competitors for substrate space between a centuries-old manmade structure and the nearest natural reef at St. Eustatius, eastern Caribbean. The artificial reef had a significantly lower species richness and fewer competitive interactions than the natural reef. The artificial reef was dominated by a cover of crustose coralline algae and zoantharians, instead of turf algae and fire corals on the natural reef. Significant differences in species composition were also found between exposed and sheltered sites on both reefs. Our study indicates that even a centuries-old manmade reef cannot serve as a surrogate for natural reefs.

The substitution of petrochemical plastics by bio-based and biodegradable plastics are in need of an evaluation for the potential toxic impacts that they can have on marine wildlife. This study aims to assess the toxicological effects of polylactic acid microparticles at two concentrations, 10 and 100 μg/L, during 8 days on the blue mussel, Mytilus edulis. No significant oxidative stress (catalase, glutathione-S-transferase and superoxide dismutase activities), neurotoxicity (acetylcholinesterase), or immunotoxicity (lysosomal membrane stability and acid phosphatase activity) were detectable. The multivariate analysis of metabolomic data allowed us to differentiate the individuals according to the exposure. From the loading plot of OPLS-DA, 48 ions down-regulated in the individuals exposed to microplastics. They were identified based on HRMS data as glycerophospholipids.