While pollution due to nano- and micro-sized plastics (NMPs) and hypoxic conditions both occur in coastal areas, the deleterious potential of co-exposure to hypoxia and NMPs (hypoxia and micro-sized plastics, HMPs; hypoxia and nano-sized plastics, HNPs) is largely unclear. Here, we provide evidence for multigenerational effects of HMP and HNP in the marine rotifer Brachionus plicatilis by investigating changes in its life traits, antioxidant system, and hypoxia-inducible factor (HIF) pathway using an orthogonal experimental design, with nanoscale and microscale particles measuring 0.05 μm and 6.0 μm in diameter, respectively, and hypoxic conditions of 0.5 mg/L for six generations. Combined exposure to NMPs and hypoxia caused a significant decrease in fecundity and overproduction of reactive oxygen species (ROS). The HIF pathway and circadian clock genes were also significantly upregulated in response to HMP and HNP exposure. In particular, synergistic deleterious effects of HNP were evident, suggesting that size-dependent toxicity can be a major driver of the effects of hypoxia and NMP co-exposure. After several generations of exposure, ROS levels returned to basal levels and transcriptomic resilience was observed, although rotifer reproduction remained suppressed. These findings help eluciating the underlying molecular mechanisms involved in responses to plastic pollution in hypoxic conditions.

Based on survey data from the Bohai Sea of China in autumn (October) and winter (December) 2019, the structural characteristics of phytoplankton communities and their relationship with environmental factors were analysed. A total of 114 species of phytoplankton belonging to 84 genera and 3 phyla were identified. Warm-water species occurred frequently but cold-water species decreased in the Bohai Sea. This was associated with global warming and rising water temperatures. By comparing with historical data, Paralia sulcata gradually flourished and became the dominant species in autumn and winter, whereas the dominance of Skeletonema costatum decreased. The marine environment of the Bohai Sea has improved significantly in recent years, and phytoplankton biodiversity has increased. In autumn, both total phytoplankton and dinoflagellates were negatively correlated with salinity, and Pseudo-nitzschia delicatissima was positively correlated with nitrite and ammonia nitrogen. In winter, Nitzschia spp. showed a positive correlation with nitrate and a negative correlation with salinity.

The sessile green macroalgae in the Neopyropia aquaculture areas of the Subei Shoal are a confirmed source of green tides in the Southern Yellow Sea (SYS) of China. The green tides have a significant impact on local economic development (tourism, aquaculture, etc.) and ecological stability. In order to develop an effective method for eliminating the green macroalgae attached to Neopyropia aquaculture rafts, this study investigated the effects of mixed acid solutions (0.0475 % hydrochloric acid [HCl] and pH 2.0 citric acid) on cell damage, chlorophyll composition, phycobiliprotein content, and the photosynthetic fluorescence characteristics of Ulva prolifera and Neopyropia yezoensis. The chlorophyll contents of U. prolifera and N. yezoensis were significantly affected by the mixed acid solutions. After treatment with a mixed acid solution (4:3 volume ratio of HCl to citric acid) for 5 s, the photosynthetic pigment content of U. prolifera was significantly different from that of normal U. prolifera. However, photosynthetic pigment content in the treated N. yezoensis increased significantly. In addition, mixed acid solution treatment had a significant effect on the Fv/Fm of U. prolifera and N. yezoensis. After mixed acid treatment (4:3 HCl to citric acid), U. prolifera completely died, but the Fv/Fm of N. yezoensis was restored after 3 d. Therefore, a mixed acid solution comprising 0.0475 % HCl and pH 2.0 citric acid (at a volume ratio of 4:3) can be used as an agent for the removal of green macroalgae from Neopyropia aquaculture areas.

Mercury pollution is a serious global environmental issue and the characterization of its distribution and its driving forces should be urgently included in research agendas. We report unusually high mercury (Hg) concentrations (>5 μg/g) along with stable isotopes values in feathers of southern rockhopper penguins (Eudyptes chrysocome) from colonies in the Southwest Atlantic Ocean. We found a highly heterogenous prevalence of Hg throughout the study area and over a three-fold higher mean Hg concentration in southernmost colonies. Variation in Hg concentrations among colonies is primarily explained by site, rather than by trophic position. We provide further support to the existence of a Hg hotspot in the food web of the Patagonian Shelf and spatially restrict it to the southern tip of South America. Our findings highlight the need for regional and colony-based seabird conservation management when high local variability and plasticity in foraging habits is evident.

We report the concentration of 13 elements in the muscle and liver of 17 coastal fish species of the Bijagós Archipelago, Guinea-Bissau, and link element concentrations to trophic ecology as assessed by carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotopes. We found higher concentrations of Hg, Fe, Mn, Cu, Zn, Se and As in liver as compared to muscle tissue, and the opposite pattern for Sr and Ca in all fish species. The concentration of Hg and Se in muscle samples increased significantly with δ¹⁵N, suggesting a biomagnification of these elements in this food chain. The concentrations of Ca and Sr, Fe and Cr, Ca and Mn, and Fe and Mn were positively correlated to each other in more than 50% of the studied species. Fish constitute the most important animal protein source for people in Guinea-Bissau, and thus assessing the concentrations of potentially toxic elements is relevant for human health.

This study investigated the structure and function of macrobenthic community in Bohai Bay upon improvement of water quality due to pollution abatement. A total of 166 species were collected in the summer and autumn sampling, with an increase in sensitive species recorded as compared to data from previous studies. While historical variations in species richness indicated signs of improvement in community structure, results of functional diversity indices revealed that the macrobenthic community in Bohai Bay was still in an early stage of recovery. From BIO-ENV analysis, habitat instability may hinder how community responded to water quality improvement. Results of the benthic habitat quality assessment also indicated that the ecological status in most areas of Bohai Bay was classified as good, while a few estuarine regions were categorized in a poor status.

Occurrence, distribution, and potential ecological risks of ten organophosphate esters (OPEs) and nine synthetic musks (SMs) were investigated in sediments from the Yangtze River Estuary (YRE) and adjacent East China Sea (ECS). The total concentrations of OPEs in the surface sediments ranged from 0.977 to 19.0 ng/g dry weight (dw) with tris(2-chloro-propyl) phosphate being the dominant component. Total concentrations of SMs ranged from 0.176 to 7.25 ng/g dw, with 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene as the dominant SMs. Higher sedimentary concentrations of ΣOPEs and ΣSMs were found in the river mouths of the YRE, inter face of Hangzhou Bay, and mud area of the ECS; the results suggested that terrestrial discharge might be the main source of OPEs and SMs in the studied region. Risk assessment revealed that low ecological risks were posed by OPEs, and limited to low ecological risks were posed by SMs.

Ultraviolet (UV) radiation can significantly increase the toxicity of polycyclic aromatic hydrocarbons (PAHs) in crude oil to early life stage (ELS) fishes through photo-induced /photo-enhanced toxicity. However, little is known about the sub-lethal effects and mechanisms of photo-induced PAH toxicity in ELS fishes. The present study investigated apoptosis and global transcriptomic effects in larval red drum (Sciaenops ocellatus) (24–72 h post-fertilization) following co-exposure to oil (0.29–0.30 μg/L ∑PAH₅₀) and UV. Apoptosis was quantified using the TUNEL assay, and transcriptomic effects were assessed using RNA sequencing analysis. Apoptotic fluorescence was greatest in the eyes and skin following 24 and 48 h co-exposure to oil and UV, indicating photo-induced toxicity. Consistent with these phenotypic responses, pathways associated with phototransduction, eye development, and dermatological disease were among the top predicted pathways impacted. The present study is the first to provide global transcriptomic analysis of UV and oil co-exposure in an ELS fish.

Health and safety of occupations entailing extensive skin contact with cinnabar-enriched sand in beaches of Friuli-Venezia Giulia (FVG) Region (North-eastern Italy) have been questioned for possible skin absorption of mercury (Hg). One hundred mg hair was collected from the occipital scalp of 50 male workers of Grado beach and 121 males from FVG general population. Factors associated with hair Hg content were investigated by multivariable logistic (considering Hg levels >1 vs ≤1 mg/kg) and log-transformed linear regression. The median hair concentration of Hg in male beach workers was 0.70 (IQR = 0.42; 1.34) mg/kg, lower than FVG general population's [1.29 (IQR = 0.87–2.06) mg/kg (p < 0.001)]. In both regression models the hair Hg increased with fish consumption, both among beach workers of Grado and FVG general population. The mean Hg levels in beach workers of Grado fell within an acceptable range, not requiring restrictions of their occupational activities.

Laboratory exposure studies allow to investigate the impact of microplastics on marine biota, but commonly lack a procedural control, i.e. assessing the effects of natural microparticles. In two experiments with the mussel Semimytilus algosus, we compared the effects of clay vs. polyvinyl chloride (PVC) and celite vs. polymethyl-methacrylate (PMMA), respectively, at concentrations of 1.5, 15 and 150 mg l⁻¹. After more than 60 days, no effects on respiration and clearance rates, mortality and byssus strength were observed. However, in mussels exposed to PVC the Body Condition Index was 34% lower at 150 mg l⁻¹ than at 1.5 mg l⁻¹. Furthermore, at 15 mg l⁻¹, mussels exposed to microplastics produced over 40% less byssus than those exposed to natural microparticles. This suggests that mussels react differently to natural microparticles and to microplastics, but only at high particle loads that exceed current environmental microplastic concentrations by orders of magnitude.