Marine pollution bulletin最新文献

This study examined the structural and functional responses of macrobenthic communities in Bohai Bay to seasonal low-oxygen conditions. Based on field observations conducted in June 2024 (normoxic conditions) and August 2024 (a seasonal low-oxygen period), we examined changes in community structure, functional diversity, and ecological quality. Functional diversity was assessed using Functional Richness (FRic), Functional Evenness (FEve), Functional Divergence (FDiv), and Functional Dispersion (FDis), while ecological quality was evaluated using the AZTI Marine Biotic Index (AMBI) and the multivariate AMBI (M-AMBI). Relationships among environmental conditions, species composition, and functional traits were explored using RLQ analysis. During the low-oxygen period, total macrobenthic abundance increased whereas biomass declined, accompanied by increased dominance of opportunistic taxa, particularly small-bodied polychaetes. Oxygen depletion acted as a strong environmental filter on macrobenthic functional traits, favoring tolerant trait modalities while suppressing oxygen-sensitive functional groups. Although AMBI and M-AMBI generally classified ecological conditions as good, FEve declined markedly under low-oxygen conditions, indicating pronounced functional convergence despite relatively stable taxonomic composition. These findings suggest that seasonal oxygen depletion primarily restructures macrobenthic communities through trait-based filtering rather than immediate species loss, and that integrating functional diversity metrics-especially FEve-with traditional biotic indices can provide earlier and more comprehensive diagnosis of ecosystem degradation in coastal systems.

This study evaluated the impacts of a wastewater treatment works (WWTW) in a regional city in Australia that releases both secondary-treated wastewater and resultant biosolids into an ocean outfall (depth: 25 m). Sediments (n = 64) were collected in both nort-heast (NE) and south-west (SW) directions at 10-20, 50-100, 200-500, and 1000-2000 m distance from the diffusers. The sediments were analysed for physicochemical properties, trace metals, microplastics (MPs), estrogenicity, and estrogenic endocrine disrupting chemicals (e-EDCs). The sediments were low in clay and organic content, but were enriched in fine sands. Most of the trace metal concentrations were below the detection limit of ICP-OES. Only the concentrations of Al, Fe, Cr, and Se were reportable, but were far below sediment quality guideline values. Average MP concentrations (size: >25-5000 μm) were also low (NE: 42 particles kg^-1; SW: 54 particles kg^-1) and were composed of 68% fibres (PET and PP) and 32% fragments (PP and PE). The estrogenicity (NE: 0.89 ng EEQ g^-1; SW: 1.19 ng EEQ g^-1) of the sediments was low to medium. Estrogenic compounds most responsible for the estrogenicity were 17β-estradiol (E2) and bisphenol A (BPA). All parameters were significantly higher near the diffusers (i.e., 10-20 m) and e-EDCs, particularly E2 might pose high ecological risks to aquatic habitats at this distance. Overall, there was limited contamination in the ocean outfall sediment, which is most likely attributable to the effect of significant oceanic dilution, deficiency of clay and organic content, and high content of fine sand in sediment.

Plastic pollution poses a serious threat to seabirds, yet the relationship between plastics and molluscivorous species remains severely understudied despite high risk of exposure to plastics in sediments and contaminated prey. As coastal benthic environments are hotspots for plastic contamination, seaducks that dive and forage on mollusks (predominantly benthic bivalves and gastropods) in coastal habitats may be particularly vulnerable. This study presents the first assessment of plastic contamination in two molluscivorous seaducks: Black Scoters (Melanitta americana) and Stejneger's Scoters (M. stejnegeri), which winter along Japan's Pacific coast. Gizzard samples from 10 individuals were analyzed using Fourier transform infrared spectroscopy after alkaline and acid digestion and density separation, providing an initial assessment of plastic contamination. Microplastics were found in all samples, with a median of 240 particles per bird, corresponding to 7.3 particles g^-1 (gizzard content). Diet and foraging habitat may drive this high plastic burden. 99.8% of the plastics were < 200 μm (a size class not considered during previous seaduck studies) and were predominantly fragments (>98% in both species) which may originate from contaminated prey. Polyethylene and polypropylene were the most common polymers identified, accounting for 78.1% of all detected plastics. However, the presence of two polystyrene microplastic pellets and one polystyrene mesoplastic sphere is a unique finding, which is potentially linked to the scoters' foraging behavior. Given seaducks' high exposure and potential health risks associated with their feeding ecology, as well as anatomical and physiological traits, further research should include quantification of nanoplastics in tissues due to the greater toxicological risks involved.

Marine ranching is increasingly used in coastal management, yet its impacts on ecosystem stability and carbon cycling are still poorly understood. Here, we integrated stable isotope analyses (δ¹³C and δ¹⁵N) with a summer Ecopath model to quantify trophic structure, carbon-flow pathways and system attributes in the Haizhidu marine ranching area (MRA) of the Bohai Sea, China, in comparison with an adjacent control area (CA). We specifically examined the intrinsic linkages between carbon transfer routes and indicators of ecosystem maturity and stability. Under summer conditions, the MRA exhibited substantially higher total system throughput, total biomass, respiration, and primary production than the CA, indicating an enlarged system scale and improved trophic development. Carbon-flow pathways were more complex and denser in the MRA, particularly between trophic levels II-IV, with the number of carbon-flow channels being nearly fifteen times that of the CA. A larger proportion of carbon was retained within low-trophic-level groups in the MRA, contributing to greater carbon storage and slightly higher transfer efficiency. Spearman correlation analysis showed that enhanced energy recycling and increased carbon-pathway complexity were strongly associated with lower TPP/TR and TPP/TB ratios, suggesting increased ecosystem maturity and stability during the study period. Overall, this summer-specific case study provides preliminary evidence that marine ranching, through artificial reef construction, can modify carbon-flow structure and potentially enhance ecosystem functioning during periods of high biological activity. Multi-season and multi-year monitoring is still required to verify whether these patterns persist across time.