Assessing the sources and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) in corals is critical, as they threaten coral ecosystem resilience in addition to other anthropogenic pressures. We determined acenaphthene, fluorene, fluoranthene, and pyrene concentration in the skeleton and soft tissue of 7 adult and 29 old specimens of the non-zooxanthellate coral Leptopsammia pruvoti from the Mediterranean Sea. Leptopsammia pruvoti accumulated 2–72 times higher PAH concentrations than the previously investigated zooxanthellate Balanophyllia europaea living at the same site at shallower depth, likely in relation to the different trophic strategy. Low molecular weight PAHs were preferentially accumulated compared to high molecular weight PAHs. Detected PAHs were mainly petrogenic, consistently with local pollution sources. Populations of L. pruvoti immobilized PAHs in the skeleton 3–4 orders of magnitude more efficiently than B. europaea. This highlights the need to investigate other non-zooxanthellate species, which represent the majority of Mediterranean scleractinians, but are widely overlooked with respect to the few zooxanthellate species.

Metal pollution in rivers should not be overlooked before their entry into the sea. However, there are few studies for estimating such contamination in rivers entering the Algerian coastal waters. Semimonthly quantification of dissolved and particulate metals, near the mouths of two industrial-tainted rivers, El Harrach and Mazafran rivers, was carried out during a period of one year. All the trace metals analyzed are originating from anthropogenic sources (EF > 1.5), with higher contamination of dissolved Pb, Cd, Zn and Ni and a slight degree of contamination of particulate Cu and Zn (0 < Igₑₒ < 1). Particulate metals show a stable complex with the particulate phase (e.g. 2 < LogKd < 6). The risk assessment results indicate that particulate Pb and Zn have a 33% likelihood of toxicity for adverse biological effects. A significant toxicity effect (ΣTUi >4) of the combined particulate metals (Pb, Cd, Cu, Zn, Cr, Ni and As) was primarily due to the higher particulate Cd, Zn, and Cr availability.

Despite the importance of estuaries as transition zones between freshwater and marine compartments, their role in the transport of microplastics is still unclear. This review analyzes the findings pertaining to the transport mechanisms and other factors that influence the fate of microplastics in estuaries. It was found that the concentration of microplastics temporally varies under daily tides, monthly tides, and seasonal flows. Moreover, it spatially varies due to density effects, biofouling, aggregation, and salinity. Wind direction and intensity impact the spatiotemporal distribution of microplastics in the water column. Some of these processes transport microplastics to the estuarine sediments. Thereafter, microplastics are prone to resuspension by turbulence and bioturbation. Hence, estuaries act as temporary sinks that retain microplastics before being flushed to the ocean. Finally, a review of highly plastic-emitting rivers shows differences in the factors affecting the transport mechanisms of microplastics, which calls for regionalization when modelling their fate henceforward.

Microplastics (MPs) in fish have attracted attention recently, for their ecological and food safety risks. However, knowledge gaps still exist regarding MPs in fugu, a special poisonous but precious seafood, especially that accumulated in its tissues. Accordingly, this study investigated the characteristics of MPs in cultured Takifugu bimaculatus which raised on three aquafarms and in wild individuals from three fishing grounds. More than 98.85 % of T. bimaculatus were contaminated by MPs and the average MPs abundance in wild fugu (4.25 ± 2.63 items/individual) was lower than that of cultured fugu (7.91 ± 2.16 items/individual). The abundance of MPs in fugu's tissues under different life patterns shows significant differences. There were marked differences in size of MPs presented in various tissues. This study adds to the knowledge on MPs accumulation in the tissues of wild and cultured fugu, providing warnings about its transmission and ecological risks in the food chain.

Numerical models point to the south-east Bay of Biscay as a convergence area for floating particles, including plastics. The few existing studies on plastic abundance in the area mainly focus on open waters and yet information on the coastal area is limited. To fill this gap, neustonic samples were taken along the coastal waters of the south-east Bay of Biscay (2017–2020) to define the spatial distribution of plastic abundances and composition. Results show an average plastic abundance of 739,395 ± 2,625,271 items/km² (998 ± 4338 g/km²). French waters were more affected, with five times higher plastic abundances than Spanish coasts. Microplastics represented 93 % of the total abundance of plastic items (28 % in weight), mesoplastics 7 % (26 %) and macroplastics 1 % (46 %). This study demonstrates that this area is a hotspot for plastic with levels in coastal waters similar to those in the Mediterranean Sea or other litter aggregation areas.

The ecological preferences of living benthic foraminifera from the riverine influx dominated eastern continental margin of India have been studied. The living benthic foraminifera were abundant on the upper slope (~100–700 m). Three distinct species assemblages were identified. Assemblage 1 (Ammonia beccari, Pseudononion costiferum, Hanzawaia nipponica, Bolivina frondalis, Bolivina dilatata, Bolivina striatula, Asterorotalia milletti) representing warmer, well-oxygenated water and coarse substrate with low organic carbon is restricted to the inner shelf. Assemblage 2 includes species (Verneuilinulla propinqua, Ammodiscus incertus, Buliminella dubia, Rotaliatinopsis semiinvoluta, Bolivina lowmani, Fursenkoina spinosa) thriving in the regions with abundant food availability and low oxygen concentration on the continental slope. The species in Assemblage 3 (Globocassidulina subglobosa, Epistominella exigua, Gyroidinoides subzelandica, Reophax longicollis, Adercotryma glomeratum, Cystammina pauciloculata, Spiroplectammina biformis) prefer deeper waters with moderate organic carbon and dissolved oxygen. The information of the ecological niches of benthic foraminifera will help in environmental impact assessment and paleoecological studies.

Interactions between microplastic (MP) and fine-grained suspended sediment in natural waters are important for the environmental fate of plastic particles. Estuaries are transitional areas between freshwater and open marine systems and are recognized as important accumulation zones for MPs. However, there is a knowledge gap on the processes driving the sedimentation of MPs in estuaries, especially with regard to positively buoyant MPs. Here we show from settling tube experiments that positively buoyant and non-spherical MP HDPE particles in different size-fractions (63–500 μm) and concentrations (1 and 5 mg l⁻¹) rapidly flocculate and settle with natural fine-grained sediment in natural seawater. Our results demonstrate that flocculation is a key process for the vertical transport of MP in estuaries. The implication is that land-based sources of positively buoyant HDPE MP transported by rivers will likely settle and accumulate in estuarine environments and thereby increase the concentration of MP in the benthic zone.

In the last decade, interest in monitoring and managing plastic pollution has greatly increased. This study compared levels of microplastic contamination in stomachs of Mugilidae fish, suggesting this family as a target for plastic pollution monitoring in areas with different degrees of anthropisation. Two sites characterised by low and high anthropic impact, a fishpond (S'Ena Arrubia, Italy) and a port (Genoa, Italy), respectively, were compared. This study highlighted a stronger microplastic contamination in the port, with a higher percentage of fish showing the presence of microplastics and a larger polymeric variability compared to the fishpond. The microplastic number in fish from the port was higher than in the literature, but it was not significantly different from S'Ena Arrubia in terms of the microplastic percentage found in single individuals. Biomonitoring of microplastic contamination in Mugilidae fish resulted in a valid tool for the investigation of areas differently affected by human activity.

The accumulation of microplastics in marine organisms is an emerging concern. Due to trophic transfer, the safety of seafood is under investigation in view of the potential negative effects of microplastics on human health. In this study, market samples of Manila clams (Ruditapes philippinarum) from South Korea were segregated into two groups of considerably different size (p < 0.05), namely small clams with shell length of 40.69 ± 3.97 mm, and large clams of shell length 51.19 ± 2.86 mm. Comparative profiling of the number, size, shape, and polymer type of microplastics were performed using μFTIR imaging and Nile red staining. Overall, μFTIR detected only 1559 microplastics while 1996 microplastics were counted based on staining from 61 Manila clams (30 small and 31 large), leading to an overestimation of 18 to 75 %. Comparable microplastics concentration, based on μFTIR, were observed at 2.70 ± 1.66 MP/g or 15.64 ± 9.25 MP/individual for the small samples, and 3.65 ± 1.59 MP/g or 41.63 ± 16.90 MP/individual for the large ones (p > 0.05). Particle diameters of 20–100 μm was the most dominant, accounting for 44.6 % and 46.5 % of all microplastics from the small and large groups, respectively. Particles, with a circularity (resemblance to a circle) value between 0.6 and 1.0, were the most prevalent, followed by fragments and fibers. At least 50 % of microplastics from the small and large samples were polystyrene, making it the most abundant polymer type. Despite the substantial difference in the size of the animals, only a weak to moderate correlation was observed between microplastics content and the physical attributes of the clams such as shell length and weight, (soft) tissue weight, and total weight (Spearman's coefficient < 0.5). The estimated intake of microplastics by the Korean population was 1232 MP/person/year via small clams, 1663 MP/person/year via large clams, and 1489 MP/person/year via clams independent of size.

The release of anthropogenic marine debris (AMD) is one of the major environmental challenges of our time. In this study, a topic model called latent Dirichlet allocation (LDA) was used to infer the research topics about AMD to provide the whole picture of the research area. The results of the LDA showed that the AMD research topics are mostly applied topics and belong to interdisciplinary or transdisciplinary research areas. Furthermore, the analysis of the temporal trends of the topics showed that topics related to such as plastic pollution exhibit an upward trend, whereas those dealing with the spatiotemporal dynamics and distribution patterns of marine debris showed a downward trend. The analysis of topic distribution over countries showed that research is scarce in landlocked countries. The findings of this study can be used as a map for the area of AMD study by various stakeholders related to marine debris issues.