Coastal environments receiving treated municipal wastewater are increasingly exposed to anthropogenic gadolinium derived from gadolinium-based contrast agents (GBCAs). However, information regarding the occurrence and fate of individual GBCAs in Mediterranean marine waters remains scarce. This study investigated total gadolinium and GBCA speciation in raw and treated wastewater from an advanced wastewater treatment plant and in the receiving waters of the Gulf of Trieste (northern Adriatic Sea). Analysis of raw and treated wastewater revealed low overall Gd removal efficiencies (∼24%), confirming that tertiary treatment processes fail to prevent GBCA discharge. High-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) identified the macrocyclic complexes gadoteridol (Gd-HP-DO3A) and gadoterate (Gd-DOTA) as the predominant GBCAs, with Gd-HP-DO3A accounting, on average, for over 60% of total Gd (Gdtot) in wastewater. An optimised solid-phase extraction (SPE) sample preparation procedure using porous carbon enabled the first determination of individual GBCAs in high-salinity Mediterranean seawater. In the Gulf of Trieste, Gd-HP-DO3A exhibited a widespread spatial and temporal presence. However, GBCAs accounted for only 2% to 37% of Gdtot in seawater samples, indicating that natural riverine geogenic sources and unmonitored macrocyclic GBCAs constitute the remaining Gd fraction. These findings confirm that persistent macrocyclic GBCAs are efficiently transferred from wastewater to Mediterranean coastal ecosystems, establishing anthropogenic Gd (Gdanth) and specific GBCA species as robust molecular tracers of wastewater effluent dispersion.
Mucilage events represent disruptive ecological and socio-economic phenomena in semi-enclosed basins. The Northwestern Adriatic Sea serves as a sentinel system for understanding these outbreaks, providing a proxy for other anthropogenically stressed and warming basins. Despite decades of research, the intricate ecological dynamics dictating the mucilage lifecycle remain poorly understood. This study applies a Machine Learning approach (Balanced Random Forest, Boruta feature selection) to a 25-year weekly dataset (2001-2025) to disentangle the interactions governing mucilage onset, persistence, and disappearance. Our models, validated through repeated cross-validation and Out-of-Bag error estimation, achieved a high predictive accuracy (AUC > 0.90), demonstrating that mucilage is a predictable outcome of "ecological memory" (cumulative influence of multi-month antecedent conditions) rather than a stochastic process. Mucilage onset follows a temporal cascade of drivers: (i) a loading phase driven by total soluble nitrogen (12-week lag); (ii) a priming phase dependent on prolonged water column stability (N2) (4-8 week lag); and (iii) a triggering phase activated by phosphorus accumulation (4-5 week lag) and a sharp thermal threshold exceeding 25 °C (1-2 week lag) abruptly triggering a high-probability outbreak. Mucilage persistence is maintained by water column stratification and low salinity (4 week lag), alongside nitrogen depletion 1 week before. The event's termination is mechanically determined by the breakdown of the pycnocline and the intrusion of mixed waters, occurring when N2 drops below the threshold of 2.9 × 10-3 s-2. Beyond offering a tool for proactive management, this study highlights the basin's vulnerability to climate change, framing mucilage as the deterministic physiological response to a sequential cascade of nutrient loading, physical confinement, and thermal stress.
This study investigated the abundance, spatial distribution, physical characteristics, polymer composition, and ecological risks of microplastics in surface sediments collected from 11 marine sites spanning bays, nearshore waters, estuaries, offshore islands, and urbanized tourist areas along Central Vietnam. Microplastics were detected in all samples, with concentrations ranging from 250 to 3217 particles/kg dry sediment. Morphologically, fragments and fibers predominated; fragments were more prevalent in bays, islands, and urban-tourism beaches, reflecting the secondary degradation of larger plastic waste, while fibers predominated in fishing port areas and textile processing zones. The size distribution showed that small MPs (50-300 μm) were dominant, with the 50-100 μm and 100-300 μm groups accounting for the majority of the total particles, and virtually no particles >500 μm were recorded. FTIR analysis revealed that polyethylene terephthalate (PET), polyethylene (PE), and fluoropolymers (PTFE) were the dominant polymers, along with numerous others with high hazard levels. The Pollution Load Index (PLI) indicates an overall pollution level of 1, but both the Polymer Hazard Index (PHI) and the Potential Ecological Risk Index (PERI) are at the highest level, highlighting that the ecological risk is primarily driven by polymer toxicity rather than particle count alone. Because density separation used NaCl, the proportions of high-density polymers (PET, PVC, PA) and the PHI/PERI values reported here are conservative estimates. This study provides the first regional baseline dataset for Central Vietnam and offers scientific evidence to support prioritized management and long-term monitoring of plastic pollution in the marine environment.
Phenanthrene (Phe) and plastic particles can co-occur in coastal waters, but their combined metabolic effects in marine bivalves remain uncertain. We exposed Mactra veneriformis to nominal Phe concentrations of 20, 50, or 100 μg L-1, 1 mg L-1 polystyrene nanoplastics (PS-NPs), or their combinations for 8 d. Non-targeted LC-MS data were reanalyzed using the aquarium as the independent experimental unit, yielding three aquarium-level profiles per treatment. Of 543 MS/MS-annotated metabolites, 36, 118, 164, and 139 met prespecified effect-size and Welch-FDR criteria in the PS-NP versus control and the three solvent-matched Phe-plus-PS-NP versus Phe comparisons, respectively. Sixteen metabolites met these criteria in all four comparisons. Exact permutation tests of the supervised models gave P = 0.10, and no KEGG pathway remained significant after FDR correction. Dynamic light scattering showed that nominal 80 nm PS-NPs formed polydisperse aggregates in artificial seawater, reaching 1664 ± 511 nm after 24 h in the highest-Phe medium. These results show that PS-NPs were associated with changes in Phe-related metabolomic response patterns under the tested suspension conditions, but they do not identify a carrier-mediated mechanism or establish environmentally representative effects.
Urbanised embayments worldwide are increasingly affected by anthropogenic release of metals and other contaminants into their surrounding waters, posing risks to both marine and human health. This study assessed metal bioaccumulation and associated sublethal effects in the benthic fish Platycephalus bassensis across eight sites in Port Phillip Bay, Australia. Metal concentrations were quantified in sediments and fish tissues (muscle, liver, gills) and traditional biomarkers, including biometric indices (condition factor, hepatosomatic and gonadosomatic indices) and detoxification enzymes (superoxide dismutase and glutathione S-transferase) were used to evaluate sublethal effects associated with tissue metal burdens. Overall, metal concentrations in sediment and fish tissues varied among sites, with higher values occurring in areas associated with intensive industrial, urban, and shipping activity. Sediment metal concentrations were generally below ANZG default guideline values (DGV-low), except for nickel, which exceeded the DGV-low value at two locations. Mercury concentrations in fish muscle (0.05-0.68 mg/kg wet weight) exceeded food-safety guidelines of 0.5 mg/kg wet weight at these locations, indicating a potential health risk to consumers. Zinc concentrations in liver tissue showed a strong positive association with superoxide dismutase activity and a negative association with hepatosomatic index, while hepatic cadmium showed a moderate negative association with glutathione S-transferase activity. Despite elevated mercury levels, no mercury-linked biomarker responses were detected. These findings highlight the limited sensitivity of traditional biochemical biomarkers in mildly contaminated ecosystems, defining an important threshold for their effective application in environmental monitoring.
Although microplastic contamination has increasingly been documented in Thai coastal environments, comparable information on monsoonal and tidal-zone variation in macroplastic debris remains limited. This study investigated sediment-embedded macroplastic debris (>5 mm) along the Rayong coast, Gulf of Thailand, during the northeast (NE), southwest (SW), and inter-monsoon (IM) periods, and surface macroplastic debris during the SW and IM periods. Embedded debris was collected from triplicate 50 × 50 cm quadrats in each of two operationally defined tidal zones at 12 stations: the high-tide line and a lower-beach position 10 m seaward. Surface litter was surveyed only during SW and IM using one 10 × 10 m quadrat at each station, covering 1200 m2 per campaign. Plastic debris was characterized by shape, color, size, and polymer composition using visual examination and ATR-FTIR spectroscopy. Mean embedded macroplastic abundance was 16.2 items m-2, peaking during NE (30.9) and at the high-tide line (19.3). Negative binomial GLMs confirmed significant monsoonal and tidal-zone effects (p < 0.05). Fibers, white items, mesoplastics (5-25 mm), PE, and PP predominated. PERMANOVA revealed significant monsoon-related variation in shape, color, size, and polymer composition. Surface-litter density was higher during IM than during SW. Correspondingly, item-based Clean Coast Index values increased from 8.27 ("moderate") during SW to 18.12 ("dirty") during IM. Sand dominated and varied spatially, but grain-size fractions were not significant with sediment-embedded macroplastic abundance. These findings provide a regional baseline for season- and location-specific monitoring and targeted plastic-litter management.
Microplastics are a global concern, but reliable high-throughput morphological candidate screening remains constrained by labor-intensive visual inspection and the limited availability of chemically supported image benchmarks. Here, we constructed an FTIR-supported image dataset from mangrove water and sediment samples and benchmarked 11 deep-learning detector configurations. The dataset contained 2865 unique FTIR-confirmed particles assigned to fragment, fiber, and film categories, together with background-only image tiles representing heterogeneous membrane residues and non-plastic interference. Among the evaluated configurations, YOLOv5m achieved the highest performance (F1 = 0.906; mAP@0.5 = 0.910). Model-derived particle counts showed a strong linear association with FTIR-confirmed counts (R2 = 0.92). Across 45 membranes, automated complete-image screening and counting with YOLOv5m required an average of 6.57 s per membrane. Performance was higher for in-distribution mangrove samples than for out-of-distribution samples, indicating that environmental background and particle heterogeneity remain important determinants of model transferability. Class-specific analysis further showed that fiber-related errors were dominated by missed detections rather than confusion with other morphological categories. The framework is intended as a morphological screening and triage tool before FTIR or Raman confirmation, providing a quick solution for microplastic monitoring in complex field samples.
Marine plastic debris (MPDs) provide artificial substrates for microalgal attachment, but how water-column phytoplankton and plastic-associated periphyton respond to environmental conditions associated with freshwater-seawater mixing remains poorly understood. We conducted a 30-day mesocosm experiment by mixing freshwater (salinity 0) and seawater (salinity 35) to establish three treatments: estuarine salinity (ES; ∼15), brackish coastal salinity (BCS; ∼30), and coastal salinity (CS; ∼35). Polypropylene attachment plates were used to examine periphyton development. In the water column, ES showed a late Chl. a maximum on day 20, BCS peaked earlier on day 10, and CS maintained low biomass with relatively stable Fv/Fm until day 20. The ES bloom did not persist despite high nitrate+nitrite concentrations, indicating possible constraints from low phosphate availability, nutrient imbalance, and low-salinity stress. On the plastic plates, Chl. a accumulated most rapidly in CS, with significantly different accumulation rates among treatments (ANOVA, F = 403.06, p < 0.001); CS showed a much higher rate (6.16 ± 0.02 μg cm-2 day-1) than ES (1.42 ± 0.23 μg cm-2 day-1) and BCS (1.24 ± 0.25 μg cm-2 day-1). Periphyton communities were dominated by diatoms, especially Navicula sp., which accounted for more than 94% of the CS periphyton community during the late phase. These results indicate that water-column phytoplankton and plastic-associated periphyton responded differently to salinity-associated environmental conditions. Overall, our findings highlight the capacity of MPDs to support distinct microalgal communities under contrasting estuarine-coastal conditions.
Seasonal oxygen depletion in stratified coastal bays drives shifts in dissolved organic matter (DOM) composition and microbial community structure, yet how DOM composition and microbial assemblages co-reorganize during the subsequent recovery phase remains poorly understood. We examined bottom-water DOM and prokaryotic assemblages across four cruises (August-October 2019) in a seasonally low-oxygen bay of the North Yellow Sea, where stratification breakdown generated a pronounced dissolved oxygen (DO) recovery gradient (2.5-7.2 mg L-1). Integrating bulk and fluorescent DOM characterization, FT-ICR MS molecular profiling, and 16S rRNA sequencing of free-living (FL) and particle-attached (PA) fractions, we show that DOM reorganization along this gradient was selective rather than uniform. DOC concentrations and a blue-shifted marine humic-like component increased with rising DO, while SUVA254 and red-shifted humic-like components declined. FT-ICR MS identified 1919 redox-sensitive formulae (RSFs) partitioned into DO-negative (sulfur-enriched) and DO-positive (CHON-enriched) pools, indicating systematic molecular-level compositional shifts during reoxygenation. Prokaryotic community composition co-varied significantly with DO independently of temperature and differed markedly between FL and PA lifestyles, although the magnitude of compositional turnover along the gradient was comparable in the two fractions (DO × lifestyle interaction, p = 0.575). Bipartite co-occurrence networks nevertheless revealed that FL communities maintained significantly denser associations with RSFs than PA communities. Together, these findings indicate that the seasonal oxygen-recovery transition acts as a selective geochemical filter, restructuring both DOM molecular composition and DOM-microbe associations in a lifestyle-dependent manner in organically enriched coastal systems.
Pharmaceuticals and personal care products (PPCPs) have emerged as contaminants of increasing environmental concern due to their continuous release, widespread occurrence, and persistence in aquatic ecosystems. Although numerous studies have investigated their occurrence, transformation, and removal, a comprehensive synthesis linking their environmental fate, associated risks, and remediation strategies remains limited. This review addresses this knowledge gap by integrating current understanding of PPCP sources, transport pathways, transformation processes, ecological and human health impacts, and emerging treatment technologies. PPCPs enter surface water, groundwater, and drinking water primarily through domestic, hospital, and industrial effluents, while the limited removal efficiency of conventional wastewater treatment plants facilitates their environmental persistence. Following their release, PPCPs undergo sorption, photodegradation, and microbial transformation, producing metabolites that may exhibit equal or greater toxicity than their parent compounds. Their occurrence has been associated with endocrine disruption, antimicrobial resistance, and chronic toxicity in aquatic organisms, highlighting the need for effective mitigation strategies. Current remediation approaches, including advanced oxidation processes, membrane filtration, adsorption, and biological treatments, offer significant potential but remain constrained by cost, scalability, and operational limitations. Overall, this review concludes that sustainable management of PPCPs requires an integrated framework combining advanced treatment technologies, comprehensive environmental monitoring, standardized risk assessment, and strengthened regulatory policies to minimize their long-term impacts on aquatic ecosystems and human health.
Plastic pollution has become a significant concern for marine environments with adverse effects on critical ecosystems such as coral reefs. Marine plastic litter items transform into new variants after prolonged exposure to the environment and interactions with organic and inorganic materials. While earlier documented variants such as plastiglomerates and plasticrusts are chiefly formed between plastic and abiogenic substrates, this study introduces plasticorals, a new form of plastic litter variant formed from plastic materials thermally adhered to or agglutinated to coral rubble. Plasticorals were incidentally observed on three beaches in Okinawa Island, Japan, during routine marine litter surveys. The plastic components of these plastic-coral agglutinate samples, examined with Raman spectroscopy showed spectral consistencies with polyethylene and polypropylene. The infiltration of skeletal pores and plastic coral interface were visualized using micro-CT scanning and microscopy. This new plastic variant provides fresh perspectives on the persistence of plastic litter in coral reef environments and highlights the potential for plasticorals to serve as future stratigraphic markers within the contemporary sedimentary record of tropical reef systems. We recommend further studies to better understand formation processes, distribution, and potential ecotoxicological impacts of plasticorals on coral reef environments.
Shipping noise is a pervasive form of underwater noise pollution, yet its effects on benthic invertebrates remain poorly integrated into spatial risk assessments. The Atlantic sea scallop (Placopecten magellanicus), a benthic bivalve supporting the world's largest wild pectinid fishery, detects low-frequency sound (100-500 Hz), overlapping the dominant range of shipping noise. Previous experiments documented life-stage-dependent valve-closure responses, with juveniles showing higher response probabilities than young adults, particularly at 100-150 Hz. We combined commercially exploited scallop-bed distributions, life-cycle information, experimentally derived acoustic dose-response relationships, and probabilistic shipping-noise models to assess the probability that shipping noise may elicit valve closure across scallop habitats in the Gulf of St. Lawrence. Particle-acceleration dose-response relationships were converted into pressure-level response functions compatible with the modeled mean-square sound pressure spectral density level, Lp,f. Their integration generated seasonal response-probability maps at 125 Hz, the modeled frequency located between the experimental frequencies of strongest response. Response probability showed strong spatial and seasonal variability. The highest probabilities occurred near major shipping routes during winter and early spring. Juveniles showed higher response probabilities and broader affected areas than young adults, reaching >30% in some beds during winter months. Several peripheral beds displayed consistently low response probabilities and may function as acoustic refuges. Because these peaks coincide with periods of elevated energetic demand, shipping noise warrants consideration in cumulative-stressor assessments and marine spatial planning. To our knowledge, this is the first spatial mapping of shipping-noise-induced behavioral-response probability for a marine invertebrate. Maps are available through the Ocean Soundscape Atlas.
Phytoplankton play central roles in marine food webs and carbon cycling, yet their responses to recurrent low-level inputs of refined oils remain poorly understood. We used a 16-day mesocosm experiment to assess the response of a natural cold-temperate/subarctic phytoplankton assemblage from the Lower St. Lawrence Estuary to repeated maritime diesel exposure. Triplicate control mesocosms were compared with triplicate diesel-amended mesocosms receiving two additions during the pre-bloom and bloom phases, equivalent to a nominal final concentration of 5.6 mg L-1 and a simulated slick thickness of approximately 13 μm. Phytoplankton biomass, cell density, size structure, taxonomic composition, and pigments were monitored using flow cytometry, image analysis, microscopy, and HPLC. Diesel exposure did not inhibit initial exponential growth but was associated with a delayed post-bloom decline in phytoplankton biomass and cell density after Day 11, strongest in the microeukaryotic fraction and bloom-forming diatoms. Grazing dilution experiments and nutrient-amended assays indicated that biomass loss was unlikely to be primarily driven by microzooplankton grazing or nutrient limitation, while viral particle density patterns showed no clear treatment-related response. Instead, the decline was consistent with diesel-associated inhibition of phytoplankton growth and biomass accumulation, potentially amplified under late-successional conditions. Although the transition toward smaller phytoplankton groups was consistent with natural post-bloom succession, it was more pronounced under diesel exposure and accompanied by stronger losses of diatom-associated biomass and pigments. These findings suggest that recurrent low-level diesel inputs can alter phytoplankton succession, reduce diatom-associated carbon biomass, and potentially modify carbon-transfer pathways in cold coastal ecosystems.
Coastal plastic pollution is routinely quantified using abundance- and mass-based metrics. These metrics are effective for trend detection, regulatory reporting and international comparison, but by design they describe the magnitude of contamination rather than its internal organisation, its commercial attribution, or the functional behaviour of the items involved. Here we operationalise and internally validate the Taxonomy-Inspired Plastic Litter Indices (TIPLI), a modular set of diagnostic metrics intended to complement conventional monitoring. Twenty-seven indices spanning structural diversity, corporate attribution, functional traits, geo-environmental dynamics, hazard weighting and network organisation were computed for harmonised, item-level coastal litter datasets from six sites in Colombia, Morocco, Brazil, Italy, Panama and Spain (Canary Islands). Richness-based indices were strongly effort-dependent (Spearman rho with sample size 0.89-0.94) and estimated sample coverage was low at product level (0.005-0.698), so raw richness contrasts are not directly comparable among sites. The first ordination axis derived from the full index set was itself correlated with assemblage size (rho = -0.94, p = 0.005). After rarefaction to common effort, product richness converged to 19.2-22.0 products per 22 items, whereas abundance-weighted diversity retained a two-group separation. In contrast, corporate concentration, functional-trait, hazard and geo-environmental indices were insensitive to effort and were estimated without bias by non-parametric bootstrapping (coefficients of variation 1.1-32.4%). The descriptive configurations reported here are therefore presented as exploratory hypotheses rather than validated classes.
Nano‑copper oxide (CuO NPs), as a highly promising antibacterial agent in aquaculture, has demonstrated excellent performance against pathogens affecting cultured organisms. However, its application is accompanied by potential toxicity risks to both the cultured organisms and the entire aquatic ecosystem. In this study, CuO NPs was synthesised using a sodium hypophosphite liquid-phase reduction method, and then a toxicity experiment was conducted using 50 μg/L CuO NPs in M. galloprovincialis. Multiple endpoints at Cu distribution, enzyme activity, lipid peroxidation degree, immune-related gene expression, tissue pathology, and metabolic response were assessed in response to CuO NPs exposure. The multi-biomarker approach revealed that CuO NPs toxicity in M. galloprovincialis operated through a coordinated network of effects: tissue-specific Cu accumulation drives histopathological damage, oxidative stress, immune disruption and ultimately systemic metabolic reprogramming. At the metabolomic level, CuO NPs exposure induced a two-system metabolic shift in M. galloprovincialis, featuring lipid upregulation and amino acid downregulation, and six metabolites (three oxylipins up, three amino acids down) that highlighted their potential as sensitive biomarkers for nanomaterial contamination. These molecular-level alterations eventually led to pathological changes in the hepatopancreas and gills. The study could provide a theoretical basis for the toxicity assessment of nanomaterials in bivalves and offer effective support for environmental risk assessments.
Halophila beccarii is one of the 10 seagrass species at risk of extinction worldwide and is listed as Vulnerable (VU) by the IUCN. To expand the baseline data on H. beccarii seagrass beds and identify the primary factors influencing their spatial distribution, this study investigated the growth and environmental characteristics of H. beccarii seagrass beds in Huachang Bay in 2025. Factor analysis and Spearman correlation analysis were adopted to explore the relationships between seagrass traits and environmental variables. The results showed that the coverage, density and biomass of H. beccarii all exhibited a declining trend. Spatially, seagrass beds near the lagoon inlet and mid-lagoon zones maintained relatively stable ecological status, whereas inner lagoon habitats suffered obvious degradation driven by intensive mariculture. Data analysis revealed that the coverage, density and biomass of H. beccarii were significantly negatively correlated with salinity, indicating that salinity acts as the primary driving factor for the degradation of H. beccarii in this region. Additionally, eutrophication and heavy metal pollution resulting from the discharge of aquaculture wastewater from shrimp ponds around Huachang Bay may also have potential negative impacts on H. beccarii. Given that the H. beccarii seagrass beds in this area have undergone a certain degree of degradation, it is recommended that Huachang Bay Nature Reserve treat seagrasses as equally key protected targets in future management and strengthen relevant conservation and management measures.
This study presents a national-scale spatiotemporal assessment of documented oil spill events in Brazilian coastal waters and the Exclusive Economic Zone between 1980 and 2022, based on the OILSPILL-BR database, a standardized online platform developed to improve public access to historical oil spill records in Brazil. A total of 234 events greater than approximately 1 t were compiled, harmonized, classified, and analyzed according to spatial distribution, temporal evolution, spill size, source, cause, oil type, and affected ecosystem. The documented incidents, corresponding to approximately 28,080 t of oil released. The Southeast region, particularly São Paulo, concentrated most records and released volume, reflecting the overlap between offshore production, port infrastructure, petroleum logistics, maritime transport, and institutional monitoring. Hotspot analysis identified recurrent spill areas associated with major oil-handling and port zones, especially São Sebastião and Santos. Temporal results showed a decline in medium and large spills, consistent with regulatory, operational, and international pollution-prevention advances, while small spills increased after the 2000s, likely reflecting offshore expansion and improved reporting. Ships were the main source of incidents and released volume, pipelines were associated with high-volume events, and offshore platforms with recurrent small spills. The study highlights the need for unified, continuously updated national databases and demonstrates how OILSPILL-BR can support environmental management, emergency planning, risk assessment and broader decision support.
Phycotoxins produced by harmful microalgae pose increasing threats to coastal ecosystems, yet their occurrence patterns and environmental drivers remain poorly understood in semi-enclosed bays. In this study, a year-round survey was conducted in Qinzhou Bay, South China Sea from November 2021 to November 2022 to investigate the prevalence, phytoplankton sources, and environmental drivers of phycotoxins. Multiple toxin groups, including paralytic shellfish toxins (PSTs), lipophilic marine algal toxins (LMATs), and amnesic shellfish toxins (ASTs), were detected throughout the investigation, with gonyautoxins (GTX) analogues, pectenotoxin-2 (PTX2), homo-yessotoxin (hYTX), and domoic acid (DA) as dominant components. Toxin occurrence exhibited pronounced seasonality, with elevated diversity and concentrations in early summer (May-June), while offshore waters represented a relative accumulation region of phycotoxins. Integrated morphological and molecular analyses identified Alexandrium spp. as key PST producers, Pseudo-nitzschia spp. as dominant DA producers, while Dinophysis and Protoceratium reticulatum, Gonyaulax spinifera, and Lingulodinium polyedra were identified as potential sources of LMATs. Environmental analyses revealed contrasting ecological controls among toxin groups: PSTs and LMATs were strongly associated with warm, saline summer conditions and dinoflagellate proliferation, whereas DA displayed distinct environmental relationships linked to diatom dynamics. It's suggested that seasonal phytoplankton succession and environmental variability jointly regulate phycotoxin occurrence. These findings reveal clear seasonal windows and accumulation regions of phycotoxins in Qinzhou Bay. The results provide a scientific basis for harmful algal blooms monitoring, early-warning systems, and risk management in aquaculture-dominated coastal ecosystems of the Beibu Gulf.
Dredging activities can alter seabed morphology and benthic communities, with long-lasting ecological consequences. This study investigates the long-term morphosedimentary and biological evolution of the CNEXO dredging pit, located in the eastern Bay of Seine (English Channel, France), more than four decades after extraction ceased. A multidisciplinary approach combining bathymetric data (1981, 2002, 2025), sediment analyses and benthic community surveys (1995, 2010, 2025) was applied to evaluate physical infilling processes and ecological recovery. Bathymetric data indicates that the pit remains partially infilled in 2025, despite substantial sediment accumulation since 1981, particularly between 2002 and 2025. Pit sediments remain heterogeneous, comprising sand, mud, and gravel derived from slope erosion and post-extraction deposition. This heterogeneity, coupled with bathymetric gradients, exerts a strong structuring effect on benthic assemblages, with redundancy analysis (RDA) showing that sediment composition and depth explain approximately 32% of community variability. Biotic indices (taxonomic richness, abundance, Shannon diversity and Pielou's evenness) revealed higher diversity and abundance within the pit than at peripheral stations. Non-metric multidimensional scaling (nMDS) highlights clear spatial and temporal gradients, reflecting a gradual convergence of pit and peripheral communities over time, consistent with the ongoing siltation of the eastern Bay of Seine. Overall, the CNEXO pit remains morphologically and ecologically distinct from surrounding habitats, a pattern supported by the Ecological Quality Status indices (MUMARINEX, GPBI, M-AMBI, and EQA), underscoring the long-term legacy of intensive, fixed-point dredging. These findings reinforce ICES recommendations advocating extensive or semi-extensive extraction practices to facilitate faster physical and biological recovery of impacted marine ecosystems.
By combining satellite technology with ecological risk analysis, this study establishes a scalable global framework for tracking the environmental effects of chronic oil slicks. We used Sentinel-1 SAR from SkyTruth's Cerulean platform to detect surface slicks potentially attributable to over 24,000 fixed oil infrastructure and 326 FxO operating locations. We validated >2000 detections through expert review. This approach generates a replicable global database of offshore oil pollution sources, exemplifying a systematic method for identifying chronic polluters.We ranked offshore oil sources globally and within European and Mediterranean EEZs based on the percentage of satellite captures that contain attributed oil slicks. We overlaid validated slick locations with marine ecoregions, protected areas, and species occurrence data from the Map of Life. For nine identified chronically polluted regions—five global and four European/Mediterranean—we extracted species assemblages across concentric 50 km buffers. Chronic oil slicking correlated with consistent differences in assemblage composition and threatened species indicators. Species richness remains relatively stable across distance classes, but species composition shifts significantly. In European/Mediterranean waters, slick proximity explained >40% of the variation in community structure, surpassing the influence of fishing intensity or coastal proximity. Globally, polygons closer to chronic slick sites contain higher threatened-species representation in the Map of Life species lists. Beta diversity partitioning suggested that turnover dominated compositional differences among slick-proximate versus farther polygons, which supports compositional differences not explained by richness alone. These results pinpoint pollution hotspots with elevated ecological vulnerability, offering a pathway to align environmental monitoring with spatial conservation priorities.
