The increase in trace element concentrations in the aquatic environment due to anthropogenic activities, urges the need for their monitoring and potential toxicity, persistence, bioaccumulation, and biomagnification at different trophic levels. Gilthead seabream is a species of commercial importance in the Mediterranean Sea, both for the aquaculture and fisheries sectors, however very little is known about their trace element contamination accumulation and the resulting effect on their health status. In the present study, 135 juveniles were collected from seven coastal lagoons known to be essential nursery areas for this species. We measured seventeen different inorganic contaminants at the individual level in fish muscle (namely Al, As, Be, Bi, Cd, Cr, Cu, Hg, Li, Ni, Pb, Rb, Sb, Sr, Ti, Tl and Zn). Our results revealed the accumulation of multiple trace elements in individuals and distinct contamination signatures between lagoons which might lead to contrasted quality as nurseries for juveniles of numerous ecologically and economically relevant fish species in addition to seabreams. We further evaluated the potential adverse effect of these complex contamination mixtures on the liver (the main organ implicated in the metabolism of xenobiotics) and red muscle (a highly metabolic organ) using a proteomic approach. Alterations in cellular organization pathways and protein transport were detected in both tissues (albeit they were not similarly regulated). Chromosome organization and telomere maintenance in the liver appeared to be affected by contaminant mixture which could increase mortality, age-related disease risk and shorter lifetime expectancy for these juveniles. Red muscle proteome also demonstrated an upregulation of pathways involved in metabolism in response to contamination which raises the issue of potential energy allocation trade-offs between the organisms’ main functions such as reproduction and growth. This study provides new insights into the cellular and molecular responses of seabreams to environmental pollution and proposed biomarkers of health effects of trace elements that could serve as a starting point for larger-scale biomonitoring programs.

The system of fertilizing agricultural soils with sludge or compost from wastewater treatment processes, as one of the principles of the circular economy, can lead to microplastic (MP) contamination. The existing technical standards for fertilization are very recent and do not consider this problem, although there is scientific evidence of their existence. Therefore, this study, on the one hand, evaluates the presence of MPs in agricultural soils, previously treated with sludge or compost from wastewater treatment plants for fertilization, and on the second hand, it studies the effect of these MPs on earthworms in three different locations in the south of Spain. For the study, selected composts deriving from the different stages of the composting process and three fertilized soils with increasing MP doses were followed. Samples were taken from different sections in depth (0–5, 5–10, and 10–20 cm) to study the shape, size, type, and abundance of MPs using infrared spectroscopy (FTIR). The results showed that the most abundant shape was fiber, followed by fragment and finally bulk, for both composts and soils. Regarding size distribution, 100 μm was the predominant size in composts (64.3% ± 9.8), while in the case of soils, the predominant range was from 100 to 500 μm. The prevalent polymers in both, composts and soils, were PTFE, TPE, PP, and PET, with four times higher amounts in composts than in soils. Ingestion of common MPs were also verified in two earthworm species, which ingested concentrations higher than 2.1% w/w. PP was the most ingested MP and Eisenia fetida was more voracious compared with Lumbricus terrestris. Therefore, it can be considered a suitable bioindicator for monitoring microplastic contamination in agricultural soil.

Rare Earth Elements (REE) and several trace elements abundances in mussel's shells collected along the St. Lawrence River, the Estuary, and the Gulf of St. Lawrence (EGSL) reveal coherent chemical variations, with a sharp contrast between freshwater and seawater bivalves. In freshwater mussel's shells, Rare Earth Elements and Y (REY) patterns are rather flat. Their Mn and Ba concentrations are higher than those of EGSL mussel shells, which are much richer in Sr. Shale-normalized REY abundances in mussel's shells from the EGSL show positive anomalies in La and Y and well-marked negative anomalies in Ce, reflecting those of seawater. Prince Edward Island shells show light REE depletion relative to PAAS, positive La and Y anomalies, and negative Ce anomalies. Our data confirm the lack of detectable Gd pollution in the St. Lawrence River and in the EGSL, as well as Pb pollution at the mouth of the Saguenay Fjord and near Rimouski.

Conservation of ecosystems is an important tool for climate change mitigation. Seagrasses, mangroves, saltmarshes and other marine ecosystems have particularly high capacities to sequester and store organic carbon (blue carbon), and are being impacted by human activities. Calls have been made to mainstream blue carbon into policies, including carbon markets. Building on the scientific literature and the French voluntary carbon standard, the ‘Label Bas-Carbone’, we develop the first method for the conservation of Posidonia oceanica seagrasses using carbon finance. This methodology assesses the emission reduction potential of projects that reduce physical impacts from boating and anchoring. We show how this methodology was institutionalized thanks to a tiered approach on key parameters including carbon stocks, degradation rates, and decomposition rates. We discuss future needs regarding (i) how to strengthen the robustness of the method, and (ii) the expansion of the method to restoration of seagrasses and to other blue carbon ecosystems.

This study addresses the scarcity of evidence on the relationship between benthic communities and coarse-grained sediments in the eastern English Channel. The region's geological history contributes to its predominantly coarse sediment composition. The study employs ternary plots to visualize benthic species' preferences and tolerance for sediment types, revealing their effectiveness. Redundancy Analyses (RDA) and species-level quantile regressions explore the influence of grain size on benthic species distribution. The results indicate a moderate impact of grain size, influenced by hydrodynamics. Estuaries, particularly the Seine Estuary, significantly shape benthic species distribution. Quantile regressions underscore the varied responses of benthic communities along the grain size gradient. The study underscores the importance of considering coarse sediments, offering insights into the complex relationship between benthic communities and sediment characteristics.

The St. Lawrence River, one of the world's largest estuaries, drains >25 % of the world's freshwater reserves and is affected by various anthropogenic effluents. Although previous studies reported micro- and nanoplastics contamination in the Estuary and Gulf of St. Lawrence (EGSL), this study provides a first evaluation of macroplastic pollution along the north and south shores of the EGSL. Plastic debris categorization was performed according to the OSPAR protocol completed by polymer identification using Fourier-transform infrared spectroscopy. The EGSL appeared ubiquitously contaminated by plastic debris, dominated by single-use plastics primarily made of polypropylene (28 %), polyethylene (25 %) and polystyrene (17 %). The EGSL shores exhibited a mean contamination level of 0.17 ± 0.11 items/m2 and distance to Montreal significantly influenced the distribution of plastic debris. This study provides an essential baseline for implementing local waste reduction and management actions in the St. Lawrence watershed to reduce plastic pollution.

Harmful Algal Blooms involving the dinoflagellate Alexandrium pacificum continue to increase in ecosystems suffering the climate warming and anthropogenic pressure. Changes in the total proteome and physiological traits of the Mediterranean A. pacificum SG C10–3 strain were measured in response to increasing temperature (24 °C, 27 °C, 30 °C) and trace metal contamination (Cu2+, Pb2+, Zn2+, Cd2+). Warming reduced the cell densities and maximal growth rate (μmax), but the strain persisted at 30 °C with more large cells. The polymetallic stress increased cell sizes, reduced cell growth at 24 °C–27 °C and it increased this at 30 °C. Toxin profiles showed a predominance of GTX4 (32–38 %), then C2 (11–34 %) or GTX6 (18–24 %) among the total Paralytic Shellfish Toxins, however these were modified under warming, showing increased contents in GTX1 (among the most toxic), GTX5, C1 and NeoSTX, while dc-NeoSTX and STX (among the most toxic) only appeared at 30 °C. Under polymetallic contamination, warming also increased contents in GTX5 and NeoSTX. In contrast, polymetallic stress, or warming had harmful effects on C2 contents. Proteins were more quantitatively produced by A. pacificum SG C10–3 under warming in accordance with the high levels of up-regulated proteins found in the total proteome in this condition. Polymetallic stress, only or combined with warming, led to low proteomic modifications (1 % or 4 %), whereas warming induced strong 52 % modified proteomic response, mainly based on up-regulated proteins involved in photosynthesis (light harvesting complex protein), carbohydrate metabolism (arylsulfatase) and translation (ribosomal proteins), and with the lesser down-regulated proteins principally associated with the lipid metabolism (type I polyketide synthase). Our results show that warming triggers a strong up-regulated A. pacificum SG C10–3 proteomic response, which, coupled to modified cell sizes and toxin profiles, could help it to withstand stress conditions. This could presage the success of A. pacificum in anthropized ecosystems submitted to global warming in which this dinoflagellate also might be more toxic.