To address knowledge gaps in microplastic (MP) fates within connected ecosystems, this study analyzes divergence and convergence across interconnected seagrass and coral habitats. Convergence was limited: Only 16% of MP categories were shared (notably black fibrous PET), and high-density MPs consistently accumulated in sediments in both ecosystems. However, divergence was pronounced. Seagrass meadows acted as selective filters that facilitated sedimentation of larger MPs, leaving smaller fractions to dominate transport to reefs, where they accumulated on coral surfaces and tissues. Notably, biological selectivity altered this pattern internally: while small MPs were prevalent, coral tissues disproportionately accumulated large (1-2 mm), high-density transparent fibers, likely triggered by physical entanglement and prey-mimicking optical cues. Seagrass leaves intercepted high-density MPs on surfaces, whereas corals were highly susceptible to internal accumulation within tissues and skeletons. Furthermore, coral skeletons served as long-term archives sequestering diverse, predominantly high-density MPs, while seagrass leaves acted as short-term dynamic traps with significantly higher surface abundance. Specifically, surface accumulation was morphologically driven, whereas internal incorporation in corals was biologically regulated and decoupled from surface loads. Mechanistically, these patterns suggest that intrinsic biological modulation is the primary driver of MP heterogeneity between ecosystems. These findings highlight the need for habitat-specific risk assessments.

Benzo[a]pyrene (BaP), a high-molecular-weight polycyclic aromatic hydrocarbon, is a persistent contaminant with well-documented developmental and endocrine-disrupting effects in aquatic organisms. This study examined how reproductive timing after exposure cessation influences transgenerational toxicity in marine medaka (Oryzias melastigma). Fish were exposed to environmentally relevant BaP concentrations (1, 4, and 8 μg/L) for 120 days, and F1 offspring were obtained from parents spawning 1, 30, and 60 days post-exposure. Offspring from 1-day post-exposure spawns showed up to 40 % reduced hatching, elevated mortality, malformations, and shorter body length, accompanied by downregulation of antioxidant (sod, cat, gpx) and steroidogenic (cyp17a, 17βhsd, cyp11b) genes and elevated thyroglobulin (tg) and vitellogenin (vtg1, vtg2). Partial recovery occurred in oxidative and apoptotic pathways at 30 days, while endocrine and growth disruptions persisted. By 60 days, most parameters normalized except thyroid- and growth-axis markers. Hormonal assays revealed increased adrenocorticotropic hormone, cortisol, elevated thyroxine, and suppressed growth hormone, indicating slow endocrine and growth recovery.

Thermal effluents from coastal nuclear power plants (NPPs) typically raise near-field seawater temperatures by 2-4 °C for several hours to days, imposing thermal stress on local marine biota. This study investigates the biochemical and molecular responses of juvenile large yellow croaker Larimichthys crocea to acute thermal stress, simulating the thermal discharges from coastal NPPs. Fish were exposed to 28 °C (control), 29 °C, 30 °C, and 32 °C, with sampling conducted at 24 h and 96 h. At 32 °C, all fish died within 48 h, while exposure to 29 °C and 30 °C for 96 h induced oxidative stress in the liver, marked by elevated lipid peroxidation and altered antioxidant enzyme activities. Transcriptomic analysis showed a significant intensification of immune responses after 96 h compared to 24 h at both 29 °C and 30 °C. Notably, immune response adaptation occurred at 29 °C, whereas at 30 °C, immune-related pathways shifted from pro-inflammatory activation to broad transcriptional suppression as the temperature approached the species' upper thermal limit. These findings highlight the narrow thermal tolerance of L. crocea, provide insights into the risks of thermal pollution from NPPs, and emphasize the need for improved coastal aquaculture management to address the impacts of climate change and ocean warming.

Microplastics (MPs) are ubiquitous marine pollutants that pose increasing ecological risks, yet their effects on intestinal physiology and gut microbial homeostasis during the juvenile developmental stages of Tachypleus tridentatus remain unclear. In this study, fifth- and sixth-instar juveniles of T. tridentatus were exposed to environmentally relevant concentrations of 6.0 μm polystyrene microplastics (PS-MPs; 0, 102, and 104 particles/L) for 7 and 21 days to investigate intestinal physiological responses and potential mechanisms associated with PS-MP exposure. Intestinal retention, oxidative stress, innate immune responses, and gut microbiota were comprehensively evaluated. PS-MP exposure induced concentration-dependent and time-dependent alterations in superoxide dismutase, catalase, malondialdehyde, and lysozyme, suggesting oxidative imbalance and modulation of innate immune responses. Fifth-instar juveniles displayed more pronounced oxidative-stress alterations and divergent innate-immune profiles relative to sixth-instar conspecifics, pointing to greater physiological susceptibility at earlier developmental stages. Gut microbiota analysis revealed pronounced dysbiosis, characterized by a reduced relative abundance of Bacillota, enrichment of Pseudomonadota, depletion of beneficial taxa (e.g., Lactococcus), and increased abundance of opportunistic bacteria, including Pseudomonas and members of Enterobacteriaceae. These physiological and microbial alterations collectively suggest that environmentally relevant PS-MPs impair intestinal homeostasis in juvenile T. tridentatus by inducing oxidative imbalance, modifying innate immune responses, and reshaping gut microbial communities, with clear instar- and exposure time-dependent effects. These findings highlight the importance of considering developmental stages in ecological risk assessment for benthic arthropods.

Thermal stress from global warming and heated discharges from coastal nuclear power plants poses a significant threat to marine aquaculture, particularly during the sensitive early life stages of fish. These discharges elevate local seawater temperatures, altering the nearshore thermal environment. This study examined the effects of elevated temperatures on early development in large yellow croaker (Larimichthys crocea), a commercially important mariculture species in China. Embryos were exposed to five temperature regimes (22, 23, 24, 26 and 28 °C) to evaluate impacts on hatching success, survival, morphology, physiology, antioxidant activity, and immune gene expression. Temperatures +4 °C and +6 °C above the optimal 22 °C significantly reduced survival and body length, induced early hatching, and increased deformities. Antioxidant enzyme activity declined, while malondialdehyde (MDA) levels rose, indicating oxidative stress. Expression of heat shock proteins showed a selective response, with hsp70 downregulated and hsp27 upregulated. Immune-related genes such as nfkb and casp1 were upregulated, while infy, myd88, and tgfb were suppressed. The integrated biomarker response version 2 (IBRv2) quantified cumulative biological stress across treatments. These findings provide insight into the temperature sensitivity of early developmental stages in marine fish and emphasize the importance of thermal assessments under changing environmental temperature conditions.

Microplastic pollution has become an emerging threat to marine biodiversity, yet the developmental-stage-specific responses of endangered marine species remain poorly understood. Tachypleus tridentatus, a threatened marine arthropod of high ecological and conservation value, is exposed to microplastics in coastal habitats. In this study, five-instar-old and six-instar-old juvenile T. tridentatus were exposed to polystyrene microplastics (PS-MPs) with a diameter of 6 μm at environmentally relevant concentrations (0, 102, 104 particles/L) for 21 days. Fluorescence imaging revealed the accumulation of PS-MPs within the intestinal tract, with distinct retention characteristics among developmental stages. Transcriptome analysis revealed significant differential gene expression after exposure, with affected pathways related to energy metabolism, immune regulation, stress response, signal transduction, and development. Younger juveniles exhibited stronger transcriptional disturbances in metabolic and stress-related pathways, whereas older juveniles showed more coordinated regulation of homeostatic and adaptive genes. These findings suggest that juvenile T. tridentatus employs age-dependent molecular response strategies when confronted with microplastic exposure, reflecting developmental differences in stress sensitivity and adaptive capacity. Our study provides new insights into the molecular mechanisms underlying microplastic responses in an endangered marine species and highlights the importance of incorporating developmental-stage variation into ecological risk assessments and conservation strategies for horseshoe crabs in polluted coastal ecosystems.

Poor thermal tolerance is a foremost issue in hybrid abalone (Lvpan abalone, Haliotis discus hannai hybrid H. fulgens) farming, while acclimation temperature and size may be key factors affecting abalones’ thermal tolerance. Evaluating the effects of acclimation temperature and size on the thermal tolerance of abalones is of great significance for guiding their farming practices and the conduct of surrounding human activities. Using critical temperature maximum (CTM) and upper incipient lethal temperature (UILT) tests, this study was conducted to assess abalones’ thermal tolerance after 21 days of acclimation at two temperatures (25 °C and 16 °C). At each temperature, abalones were divided into small (average weight 6.85 ± 1.97) and large (average weight 41.33 ± 8.41) groups. The CTM test applied heating rates of + 1 °C/h, + 2 °C/h, + 4 °C/h, + 6 °C/h, and + 8 °C/h. The UILT test, tailored to the acclimation temperature, used temperature shocks of + 2 °C (27 °C), + 4 °C (29 °C), + 6 °C (31 °C), + 8 °C (33 °C), and + 10 °C (35 °C) in the high acclimation temperature group and + 8 °C (24 °C), + 12 °C (28 °C), + 16 °C (32 °C), + 18 °C (34 °C), and + 20 °C (36 °C) in the low acclimation temperature group. In the CTM tests (n = 11), the maximum critical temperature and death temperature of each abalone were recorded across three repeats. The semi-lethal temperature was determined via exponential model fitting. In the UILT test (n = 33), abalone mortality was monitored over 24 h, with the Probit model calculating the 24-h semi-lethal temperature. Results showed that higher acclimation temperatures significantly increased the maximum critical temperature for both abalone sizes (P < 0.05) and the initial death temperature at lower heating rates (+ 1 °C/h and + 2 °C/h, P < 0.05). However, they did not significantly affect the initial death temperature at higher heating rates nor the semi or absolute lethal temperatures across all rates (P > 0.05). In the UILT test, regardless of the temperature or size, abalones begin to die rapidly at around 31 °C. The 24-h semi-lethal temperatures for large abalones were 31.1 °C (high acclimation temperature) and 29.1 °C (low acclimation temperature), and for small abalones, 30.9 °C and 29.6 °C, respectively. Comparing the two size groups revealed almost no significant differences in all indicators (P > 0.05). In conclusion, higher acclimation temperatures can improve the sensitivity of Lvpan abalones to heat stress, but cannot alter their inherent death temperature. Size does not significantly affect abalones’ thermal tolerance or their response to temperature acclimation.

Benzo[a]pyrene (BaP), a widespread environmental pollutant, has been extensively studied; however, knowledge gaps remain regarding its sex-specific reproductive toxicity and the persistence of its transgenerational effects. Marine medaka (Oryzias melastigma) were exposed to environmentally relevant BaP concentrations (1, 4, and 8 μg/L) throughout the F0 generation, with transgenerational effects assessed in F1, F2, and F3 generations reared in clean seawater. BaP exposure significantly affected biometric responses and reproductive parameters, including impaired gametogenesis, reduced fecundity, and decreased fertilization rates. Males were more sensitive to oxidative stress and hormonal imbalances in the gonads and showed delayed recovery during depuration. Genes in the hypothalamus-pituitary-gonad-liver (HPGL) axis were disrupted in a sex-specific manner. A persistent feminization and poor egg quality were observed up to the F2 generation, indicating transgenerational endocrine disruption. Despite recovery initiation in F3, the results reveal persistent sex-specific reproductive toxicity, emphasizing the need to assess sex-specific and transgenerational effects in ecotoxicology.

The release of cesium (Cs) isotopes from treated nuclear-contaminated water at Japan's Fukushima Daiichi Nuclear Power Plant (FDNPP) has raised global concern due to their potential long-term environmental impacts. Some of these isotopes have a physical half-life of 30.17 years, posing a potential threat to marine environments and marine life. This study used the stable isotope 133Cs to simulate exposure and assess the ecological risks associated with Cs isotopes in marine environments. The black porgy (Acanthopagrus schlegelii) was selected as the model organism and was exposed to various concentrations of 133Cs (0.02, 0.2, 2, and 20 mg/L). Although 133Cs exhibited low bioaccumulation in black porgy, it still showed potential for biomagnification. The fish demonstrated a strong stress response and some antioxidant adaptation at 3 days, but significant cellular and tissue damage occurred after 14 days of exposure. Analysis of the Integrated Biomarker Response version 2 (IBRv2) further revealed that the black porgy was more sensitive to Cs at 3 days, with toxic effects intensifying over time. This study provides a scientific basis and experimental reference for assessing the ecological risks of Cs isotopes in marine ecosystems.

The pollution of micro- and mesoplastic (MMP) in the Eastern Indian Ocean (EIO) remains poorly understood. The present study revealed that MMP abundance in nekton from EIO in 2022 (mean: 2.30 +/- 0.39 items individual-1 and 1.81 +/- 0.54 items g- 1 ) was significantly higher than that in 2021 (mean: 1.60 +/- 0.22 items individual- 1 and 0.80 +/- 0.13 items g- 1 ). In contrast, MMP abundance in surface water varied insignificantly between 2021 (mean: 0.04 +/- 0.01 items m-3) and 2022 (mean: 0.05 +/- 0.02 items m-3). The rise in predominant polymers-polypropylene (PP), rayon (RA), and polyester (PES)-in nekton from 2021 to 2022 may suggest increased pollution from face masks and home textiles along coastal regions. Notable spatial variation in PP and RA between the northeastern and southeastern regions was observed only in nekton, suggesting they are better indicators of MMP spatiotemporal variation than surface water. Shadow driftfish ingested more MMPs than purpleback flying squid and mackerel scad, likely due to its deeper habitat. By simultaneously considering color, composition, and shape, integrated MMP analysis showed insignificant correlation between MMP pollution in surface water and nekton, suggesting that nekton may ingest MMPs through multiple pathways beyond surface water. Risk indices for surface water and nekton reached moderate to upper levels globally, emphasizing the need for continued monitoring in the EIO. Epoxy resin, rubber, and PP + acrylic were identified as the most hazardous polymers, providing a valuable basis for developing effective strategies to mitigate plastic pollution.

While higher latitudes are becoming relatively warm ecosystem for phytoplankton, the rapid and active adaptation of harmful algal cells to cold conditions also contributes to their poleward colonization, which has scarcely been studied. We examined the adaptive mechanism to cold stress in Gymnodinium catenatum, a eurythermic species that has been recently reported to spread to higher latitudes. Using the in-situ focal plane array Fourier transform infrared spectroscopy (FPA-FTIR) imaging combined with transmission electron microscopy, we demonstrated that this dinoflagellate could adapt to cold stress by establishing two cell barriers: one consisting of the massive extracellular polymeric substances (EPS) that accumulated outside the cell and the other represented by lipid phase separation within the reshaped cellular microenvironment. Two-dimensional correlation (2D-COS) spectroscopy further revealed that intracellular bio-macromolecules (lipids, proteins, and carbohydrates) were organized in an ordered and purposeful manner to resist cold. Transcriptome analysis confirmed the inhibition of nicotinamide adenine dinucleotide (NADH) dehydrogenase and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) involved in protein and carbohydrate metabolism, in cold-treated cells. This study elucidated a flexible adaptation strategy of G. catenatum at the bio-macromolecular level and generally discussed the widespread colonization of harmful microalgae at higher latitudes.

Cathelicidin is a family of antimicrobial peptides in vertebrates that plays an important role in resistance and immunization against pathogenic microorganisms. In the present study, the full-length cDNA sequences of four novel cathelicidins (cathelicidin-1 to cathelicidin-4) in the tiger frog Hoplobatrachus rugulosus, encoding 153, 188, 132, and 160 amino acids, respectively, were firstly cloned by rapid amplification of the cDNA ends (RACE) technique. Sequence comparison and phylogenetic tree analysis indicated that the structures of the four cathelicidins are highly diverse. Afterwards, the tissue distribution profiles and antimicrobial patterns of cathelicidins in H. rugulosus were determined by real-time PCR. The four cathelicidins showed tissue-specific distribution patterns in the healthy frogs, and the transcriptional levels of cathelicidins exhibited a tissue- and timedependency profile in the frogs challenged with pathogenic bacteria Aeromonas hydrophila for 72 h. The synthetic peptides of cathelicidin-1 and cathelicidin-2 exhibited broad-spectrum in vitro antimicrobial activity, and cathelicidins exerted antimicrobial activities through excessive induction of reactive oxygen species and direct disruption of the microbial membrane structure. In addition, the intraperitoneal injection of cathelicidin proteins significantly increased the marine medaka Oryzias melastigma resistance to bacterial challenges. The existence of multiple cathelicidins, their distinct tissue distribution patterns, and the inducible expression profiles suggest a sophisticated, highly redundant, and multilevel network of antimicrobial defense mechanisms in tiger frogs. This study provides evidence that cathelicidins have antimicrobial and immunomodulatory activities, and cathelicidins derived from H. rugulosus have potential therapeutic applications against pathogenic infections in aquaculture.

Global warming may affect the health of marine species. However, the collected information on quantitative assessment of response in fish under elevated temperature is poorly defined. The present study aimed to quantitatively evaluate the effects of the hybrid grouper ( Epinephelus fuscoguttatus female x Epinephelus lanceolatus male ) under elevated temperature (33 degrees C and 36 degrees C, ET1 and ET2) stress for 14 days. As endpoints, we examined changes in body growth, hemato-immunological parameters, liver oxidative stress markers, as well as changes of the stomach digestive enzymes. Compared to the control, the body weight was significantly decreased in ET2 group for 14 d exposure, and a remarkable change of differential leukocyte counts of the fish was observed in ET1 group at 3 d and in ET2 group at 14 d. The respiratory burst activity of the hybrid grouper leukocytes markedly decreased in the treatment groups after 14-d exposure. Overall, the antioxidant enzyme activities and transcriptional levels of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GSH-PX) were markedly inhibited in the liver for 3-d and 14-d exposure. The expression levels of nf kappa b mRNA were significantly inhibited while the expression levels of atp2b1 mRNA were significantly induced after 14-d exposure. The activities of pepsin and lipase in the stomach were significantly reduced. In addition, an innovative hazard classification system (ET-HCS) was developed to quantitatively characterize the stress response of the fish following elevated temperature treatments. The stress level of ET2 group for 14-d exposure was ranked as level IV (high stress), and the other treatments were ranked as level II (low stress). Taken together, the findings of this study further extend our understanding of quantitative assessment of response in fish under high-temperature stress, which provides valuable information for improving countermeasures of mariculture industry.

Petroleum hydrocarbon pollution is a global concern, particularly in coastal environments. Polycyclic aromatic hydrocarbons (PAHs) are regarded as the most toxic components of petroleum hydrocarbons. In this study, the biomonitoring and ranking effects of petroleum hydrocarbons and PAHs on the marine fish model Oryzias melastigma embryos were determined in the Jiulong River Estuary (JRE) and its adjacent waters in China. The results showed that the levels of petroleum hydrocarbons from almost all sites met the primary standard for marine seawater quality, and the concentrations of the 16 priority PAHs in the surface seawater were lower compared with those in other coastal areas worldwide. A new fish expert system based on the embryotoxicity of O. melastigma (OME-FES) was developed and applied in the field to evaluate the biological effects of petroleum hydrocarbons and PAHs. The selected physiological index and molecular indicators in OME-FES were appropriate biomarkers for indicating the harmful effects of petroleum hydrocarbons and PAHs. The outcome of OME-FES revealed that the biological effect levels of the sampling sites ranged from level I (no stress) to level III (medium stress), which is further corroborated by the findings of nested analysis of variance (ANOVA) models. Our results suggest that the OME-FES is an effective tool for evaluating and ranking the biological effects of marine petroleum hydrocarbons and PAHs. This method may also be applied to evaluate other marine pollutants based on its framework.

Global warming poses a significant threat to coastal ecosystems and aquaculture. Moreover, nuclear power plants (NPPs) also release excess thermal energy into the environment, contributing to rising seawater temperatures and exacerbating this threat. However, studies on the potential negative impacts of thermal pollution on mariculture are scarce, especially in field environments. Herein, a comparative investigation of hybrid abalone (Haliotis discus hannai female x Haliotis fulgens male) under thermal stress was performed in laboratory and field to evaluate the potential ecological risks of NPP thermal discharge. The survival rate, behavioral changes, antioxidant enzyme activity, and transcriptional profiles of antioxidant-relevant genes were determined in hybrid abalones under thermal stress. Under a natural water temperature of 29 degrees C, an increase of 4 degrees C led to the death of all abalones. In the field study, a temperature increase of 2 degrees C resulted in the partial death of these abalones and a decrease in their adhesion capacity, which did not occur in laboratory. In addition, thermal stress caused considerable changes in the antioxidant enzyme activity in these abalones, including superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase, and malondialdehyde content. Moreover, transcriptional levels of sod, cat, and heat shock protein 70 genes were substantially induced in laboratory and field studies. The integrated biomarker responses version 2 (IBRv2) method was used to comprehensively assess the effects of thermal discharge on the abalones. The relationship between the IBRv2 values and thermal stress is not linear. These results provide valuable information for policy makers regarding the impacts of thermal discharge on marine aquaculture and the importance of establishing aquaculture safety zones near NPPs.

Here, we investigate the effects of acute and chronic exposure to arsenate (AsV) and arsenite (AsIII) in the marine medaka Oryzias melastigma. In vivo effects, biotransformation, and oxidative stress were studied in marine medaka exposed to the two inorganic arsenics for 4 or 28 days. An investigation of embryonic development revealed no effect on in vivo parameters, but the hatching rate increased in the group exposed to AsIII. Exposure to AsIII also caused the greatest accumulation of arsenic in medaka. For acute exposure, the ratio of AsV to AsIII was higher than that of chronic exposure, indicating that bioaccumulation of inorganic arsenic can induce oxidative stress. The largest increase in oxidative stress was observed following acute exposure to AsIII, but no significant degree of oxidative stress was induced by chronic exposure. During acute exposure to AsV, the increase in the enzymatic activity of glutathione-S-transferase (GST) was twice as high compared with exposure to AsIII, suggesting that GST plays an important role in the initial detoxification process. In addition, an RNA-seq-based ingenuity pathway analysis revealed that acute exposure to AsIII may be related to cell-cycle progression. A network analysis using differentially expressed genes also revealed a potential link between the generation of inflammatory cytokines and oxidative stress due to arsenic exposure.

Rapid, anthropogenic activity-induced global warming is a severe problem that not only raises water temperatures but also shifts aquatic environments by increasing the bioavailability of heavy metals (HMs), with potentially complicated effects on aquatic organisms, including small aquatic invertebrates. For this paper, we investigated the combined effects of temperature (23 and 28 degrees C) and methylmercury (MeHg) by measuring physiological changes, bioaccumulation, oxidative stress, antioxidants, and the mitogen-activated protein kinase signaling pathway in the marine rotifer Brachionus plicatilis. High temperature and MeHg adversely affected the survival rate, lifespan, and population of rotifers, and bioaccumulation, oxidative stress, and biochemical reactions depended on the developmental stage, with neonates showing higher susceptibility than adults. These findings demonstrate that increased temperature enhances potentially toxic effects from MeHg, and susceptibility Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat

Global warming and the changes in environmental conditions such as temperature and salinity may affect the health of marine species. However, the underlying mechanisms remain poorly characterized. The objectives of the present study were to examine the liver transcriptome and proteome of the marine species, hybrid grouper (E. fuscoguttatus 9 x E. lanceolatus & MALE;), to assess which physiological pathways are modulated by exposure to climate change-related stressors, how the responses vary with exposure duration, and whether they represent adaptive or maladaptive changes. To answer these questions, the hybrid grouper was subjected to single stressors (elevated temperatures, reduced salinity) or stressor combinations for 3 or 14 days. As endpoints, we examined changes in body and organ growth, liver histopathology, lipid accumulation, and alterations of the liver transcriptome and proteome. The results demonstrated that the elevated temperature resulted in reduced body weight and a reduced liver-somatic index after a 14-day exposure. The spleen-somatic index was significantly decreased compared to controls after 3-day treatment. At the transcriptomic level, the pathways with the greatest numbers of differentially expressed genes at day 3 of exposure were immune-related in all treatment groups. After 14 days of exposure, the transcriptomic and proteomic analyses showed that metabolic and protective processes became activated. The increased lipid droplet accumulation in the hepatocytes is corroborated by the transcriptomic/proteomic findings which show alterations in the pathways of lipid metabolism and fatty acid oxidation. While these changes may represent adaptive responses, the increase of hepatic lipid accumulation despite an overall loss of liver and body weight may represent a maladaptive process. Overall, the physiological responses of the hybrid grouper showed a clear time dependency, and they were partly stressor-specific, with the low salinity treatment separating from the treatments with elevated temperature. When both stressors were combined, the temperature effect dominated the salinity effect.

The status and ecological impacts of sedimentary elements of the marginal seas of Arctic and Northern Pacific Oceans was investigated during 2016 to 2018 by using inductively coupled plasma mass spectrometry. Industrial (0.006 mg kg -1-64.6 g kg -1), precious (0.003-43.8 mg kg -1), rare earth (0.006-112.9 mg kg -1), and heavy metal (0.009-398.9 mg kg -1) elements showed spatial variation, and temporal uniformity. The results indicated sigma REEs and light REEs enrichment compared to chondrite and heavy REEs, respectively, while nonsignificant positive and negative delta Ce and delta Eu anomalies existed, respectively. High contamination and extreme enrichment of priority control, industrial (As, Mo, Re, Sb), precious (Au, Ir, Pd, Pt, and Ru) and RE elements indicated potential moderate to high ecological and biological risks. The study highlighted the ecological importance and fragile nature of these ecosystems and calls for an urgent action to ensure sustainability of these ecosystems.

Although evidence suggests the ubiquity of meso- and microplastics (MMPs) in mangrove forests, our knowledge of their bioavailability and risk on mangrove leaves is scarce. Here, we investigated MMP contamination concerning submerged mangrove leaves and herbivorous snails that mainly feed on them from the four mangrove forests located in Beibu Gulf, Guangxi Province, China. Results showed that the MMP abundance on the mangrove leaves ranged from 0.01 ± 0.00 to 0.42 ± 0.15 items cm-2, while it ranged from 0.33 ± 0.21 to 6.20 ± 2.91 items individual-1 in the snails. There were significant positive correlations between snails and leaves regarding the abundance of total MMPs and the proportions of MMPs with the same characteristics. Expanded polystyrene (EPS) that mainly derived from aquaculture rafts, accounted for a major component both on the leaves and in the snails in Shi Jiao (SJ). Both the detection frequency and percentage of larger EPS (2.00-17.50 mm) on the leaves in SJ were higher than other sites. Meanwhile, the detection frequency, abundance and percentage of larger EPS on the leaves had significant positive correlations with those of micro-EPS in the snails. These findings suggested that mangrove leaves may represent a viable pathway for MMPs to enter the herbivorous snails. Larger EPS with higher frequency of occurrence on mangrove leaves were more likely to be encountered and ingested by snail considering its opportunistic feeding behavior. In addition, 11 sensitive genes involved in the processes of metabolism, intestinal mucosal immune systems, and cellular transduction in the snails were significantly suppressed by MMP exposure, which may be potentially used as early biomarkers to indicate the biological effects of MMPs under realistic environmental conditions. Overall, this study provides novel insights into the fate, sources, and biological effects of MMPs on mangrove leaves.