Knowledge of the status of the black-lipped pearl oyster Pinctada margaritifera populations is critical for the sustainability of the French Polynesia black pearl farming industry. Indeed, this activity relies on collection of spat settling out of the water column, which is inherently related to the abundance of in situ benthic stocks and their reproductive capacities. From surveys performed between 2016 and 2021, we present new stock assessments of natural wild oyster populations from four contrasted pearl farming lagoons (Gambier, Takapoto, Raroia, Takume). Also using Ahe atoll historical data, we first highlight how results vary with the methods (Direct, Zonal and Cokriging) used to scale in situ density measurements to lagoon-scale stocks. Takapoto and Gambier populations were also previously surveyed at least twice since the 1980s, allowing to demonstrate with field data clear changes in stock distributions and population structures. The consequences of our findings are discussed to provide recommendations for stock monitoring and management in the future.

The pearl-farming industry depends mostly on the natural recruitment of pearl oysters. Little is known about the relative influence of different ecological processes on the natural recruitment of pearl oysters across biogeographical scales. Spatio-temporal dynamics of bivalve larvae and spats were described at Ahe and Mangareva, 1500 km apart across French Polynesia. We quantified the effect of candidate environmental predictors on the dynamics of larvae. Both lagoons showed similar temporal dynamics with twice more larvae and 6 times more spat in Ahe. Pinctada maculata spat were more abundant than for P. margaritifera at both lagoons. While the temporal dynamics in larvae abundance were best explained by a positive effect of temperature in Ahe, the dynamics in Mangareva were poorly predicted by the environmental variables, meaning bivalve early-life stages perform better in Ahe than Mangareva suggesting a mismatch between the relevant environmental forces driving larval dynamics at these two contrasting lagoons.

Assessing the status of marine pollution at regional and sub-regional scales requires the use of comparable and harmonized data provided by multiple institutions, located in several countries. Standardized data management and quality control are crucial for supporting a coherent evaluation of marine pollution. Taking the Eastern Mediterranean Sea as a case study, we propose an approach to improve the quality control procedures used for sediment pollution data, thus supporting a harmonized environmental assessment. The regional ranges of contaminant concentrations in sediments were identified based on an in-depth literature review, and the lowest measured concentrations were evaluated to determine the “background concentrations” of chemical substances not yet targeted in the Mediterranean Sea. In addition, to verify the suitability of the approach for validating large data collections provided by multiple sources, the determined ranges were used to validate a regional dataset available through EMODnet data infrastructure.

This study uses Cu and Zn isotopic compositions as proxies of sources and metal transfers in the planktonic food webs from the Mediterranean Sea. Plankton was collected in spring 2019 in the deep chlorophyll maximum (DCM) along a North-South transect including coastal and offshore zones (MERITE-HIPPOCAMPE campaign). δ65Cu and δ66Zn were determined on four planktonic size fractions from 60 to 2000 μm. Combined δ65Cu and δ66Zn with geochemical tracers (Ti, particulate organic phosphorus) showed that geogenic particles were ubiquitous with plankton assemblages. The δ15N ecological tracer showed that planktonic food web was enriched in heavy isotopes of Cu and Zn in the higher trophic levels. δ65Cu were correlated with picoplankton in the offshore zone, and with zooplankton in the southern coastal zone. Firmicutes bacteria were found correlated with δ66Zn in northern and southern coastal zones suggesting decomposition of particulate matter at the DCM. These findings suggest that biogeochemical process may impact Cu and Zn isotopy in the planktonic community.

Although banned for years, organochlorine pesticides and PCBs continue to affect aquatic life, dolphins being particularly exposed. The concentrations of 31 PCB congeners, and 15 banned pesticides or metabolites were measured in 5 tissues of 68 striped dolphins stranded in the Northwestern Mediterranean coast in 2010–16. The results were compared to historical data (1988–2009) and, even though there is a slow decreasing trend, the levels in the 2010–2016 samples were still elevated based on common cetacean toxicological thresholds. A transition period in 2007–08, probably caused by a morbillivirus epizootic amplified the stranding, espacially of highly contaminated specimens. From 2010, higher proportions in parent compounds towards metabolites were observed yet again. These changing patterns were likely reflect the exposure of dolphins to the remobilization of pollutants from contaminated soils and sediments, with a prominent role of rivers. This should lead to an even slower decline of these contaminants that could last for decades, requiring new efforts to reduce their dispersal to aquatic ecosystems.

Ecological baselines for the structure and functioning of ecosystems in the absence of human activity can provide essential information on their health status. The Glorieuses islands are located in the Western Indian Ocean (WIO) and can be considered as “pristine” ecosystems that have not been subjected to anthropogenic pressure. Their nutrient context and the microbial assemblages were assessed by determining the abundance of heterotrophic prokaryotes (archaea and bacteria), picocyanobacteria, picoeukaryotes, microphytoplankton and protozooplankton communities in five stations, during two contrasted periods (November 2015 and May 2016). Chlorophyll-a concentrations were always under 1 μg/L and associated to very low levels in orthophosphates, nitrate and dissolved organic carbon, revealing an ultra-oligotrophic status for the Glorieuses waters. Picocyanobacteria confirmed the ultra-oligotrophic status with a predominance of Synechococcus. Zeaxanthin associated with the presence of picocyanobacteria represented the major pigment in both surveys. Three indices of diversity (species richness, Shannon and Pielou indexes) from microscopy observations highlighted the difference of diversity in microphytoplankton between the surveys. A focus on a 16S metabarcoding approach showed a high dominance of picocyanobacteria, Alpha- and Gammaproteobacteria, regardless of station or period. Multivariate analyses (co-inertia analyses) revealed a strong variability of ecological conditions between the two periods, with (i) high nutrient concentrations and heterotrophic nanoflagellate abundance in November 2015, and (ii) high heterotrophic prokaryote and picoeukaryote abundance in May 2016. The impact of a category 5 tropical cyclone (Fantala) on the regional zone in April 2016 is also advanced to explain these contrasted situations. Relative importance of top-down factors between bacterial and heterotrophic nanoflagellates was observed in November 2015 with an active microbial food web. All the results indicate that three microbial indexes potentially can be considered to assess the ecological change in Glorieuses marine waters.

Microplastics are a relevant environmental concern in marine ecosystems due to their ubiquity. However, knowledge on their dispersion patterns within the ocean basin and the interaction with biota are scarce and mostly limited to surface waters. This study investigated microplastic contamination in two species of deep-sea cephalopods from the southwestern Atlantic with different ecological behaviour: the vampire squid (Vampyroteuthis infernalis) and the midwater squid (Abralia veranyi). Microplastic contaminated most of the evaluated specimens. V. infernalis showed higher levels of contamination (9.58 ± 8.25 particles individual−1; p < 0.05) than A. veranyi (2.37 ± 2.13 part. ind.−1), likely due to the feeding strategy of V. infernalis as a faecal pellets feeder. The size of extracted microplastics was inversely proportional to the depth of foraging. The microplastics were highly heterogeneous in composition (shape, colour and polymer type). Our results provide information regarding microplastic interaction with deep-sea organisms and evidence of the biological influence in the microplastic sinking mechanism.

The Mediterranean Sea water bodies are ones of the most polluted, especially with microplastics. As the seafloor is the ultimate sink for litter, it is considered a hotspot for microplastic pollution. We provide an original analytical development based on the coupling of tandem mass spectrometry to pyrolysis-gas chromatography to improve the detection of plastic contamination in marine organisms. Due to the high selectivity of the mass spectrometer, a straightforward sample preparation consists uniquely of potassium hydroxide digestion. The quantification of six common polymers is possible in one run. The method was applied to analyze the plastic content from 500 μm down to 0.7 μm in the whole body of seven benthic species with variable feeding modes. Plastic was detected in all samples, with an almost systematic detection of polypropylene and polyethylene. Our method presents a major development in determining the levels of plastic contaminations in samples with rich organic matter content.

Rising evidence of both experimental and epidemiological studies suggests that phthalate exposure may contribute to increased risks of metabolic disorders. But there is limited research on the childhood dyslipidemia. Our cohort study was conducted in Xiamen city, Fujian Province, China. A total of 829 children (mean age 8.5 years) were included with collection of urine, blood samples and demographic data in May 2018 and followed up once a year from 2018 to 2020. We performed adjusted log-binomial regressions to examine associations between sex-specific tertiles of seven phthalate metabolites and dyslipidemia in visit 1, as well as persistent dyslipidemia and occasional dyslipidemia. We also used generalized estimating equation models (GEE) to explore the relationships between log-transformed phthalate metabolites and lipid profiles. In adjusted models, the prevalence and RRs of dyslipidemia increased with tertile group of mono-n-butyl phthalate (MnBP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), and summed di-(2-ethylhexyl) phthalate (∑DEHP) metabolites with a dose-response relationship in visit 1, as well as persistent dyslipidemia. Higher MnBP, ∑LMWP, MEHHP, MEOHP, and ∑DEHP concentrations were also associated with higher levels of log-transformed triglycerides (TG). Boys were more vulnerable to phthalates exposure than girls. In conclusion, children in China were widely exposed to phthalates, and phthalates exposure during childhood might significantly increase the risk of dyslipidemia and a higher level of lipid profiles, particularly in boys.

Black carbon (BC) aerosol negatively affects air quality and contributes to climate warming globally. However, little is known about the relative contributions of different source control measures to BC reduction owing to the lack of powerful source-diagnostic tools. We combine the fingerprints of dual-carbon isotope using an optimized Bayesian Markov chain Monte Carlo (MCMC) scheme and for the first time to study the key sources of BC in megacity Guangzhou of the Pearl River Delta (PRD) region, China in 2018 autumn season. The MCMC model-derived source apportionment of BC shows that the dominant contributor is petroleum combustion (39%), followed by coal combustion (34%) and biomass burning (27%). It should be noted that the BC source pattern is highly sensitive to the variations of air masses transported with an enhanced contribution of fossil source from the eastern area, suggesting the important impact of regional atmospheric transportation on the BC source profile in the PRD region. Also, we further found that fossil fuel combustion BC contributed 84% to the total BC reduction during 2013–2018. The response of PM₂.₅ concentration to the ¹⁴C-derived BC source apportionment is successfully fitted (r = 0.90) and the results predicted that it would take ∼6 years to reach the WHO PM₂.₅ guideline value (10 μg m⁻³) for the PRD region if the emission control measures keep same as they are at present. Taken together, our findings suggest that dual-carbon isotope is a powerful tool in constraining the source apportionment of BC for the evaluations of air pollution control and carbon emission measures.