Seasonal variation in environmental conditions profoundly influences host-microbe interactions and nutrient dynamics in marine invertebrates. This study investigated the seasonal changes in body wall nutritional components and gut microbiota of the sea cucumber Apostichopus japonicus in a marine ranching system. Significant seasonal fluctuations were observed in crude protein, lipid content, and key fatty acid and amino acid profiles, with autumn identified as a peak phase for nutrient accumulation. High-throughput 16S rRNA sequencing revealed pronounced shifts in gut microbiota diversity and community composition across seasons, with Proteobacteria and Bacteroidetes as dominant phyla. Co-occurrence network and neutral model analyses indicated that microbial community assembly was primarily governed by stochastic processes, particularly ecological drift and dispersal limitation. Strong correlations between specific microbial taxa and host fatty acids or amino acids suggest that gut microbes actively participate in host metabolic regulation, especially under thermal and nutritional stress. These findings provide new insights into host-microbiota interactions and ecological adaptation mechanisms in sea cucumbers, with implications for sustainable aquaculture management.

Enrofloxacin is one of the antibiotics commonly used in aquaculture. Nevertheless, the precise mechanisms underlying its toxicological effects on the energy metabolism of organisms remain elusive. Therefore, we conducted experiments employing grass carp (Ctenopharyngodon idellus) as our model organism, subjecting them to varying concentrations of ENR for a duration of 21 days followed by a 14-day purification period. Our results revealed that ENR exposure led to disturbances in the intestinal flora of grass carp, inducing hypoglycemia by impeding gluconeogenesis while promoting glycolysis and aerobic metabolism. Additionally, it curtailed lipid utilization and catabolism in grass carp, resulting in hepatic function impairment and metabolic disorders. The effects were partially alleviated after a 14-day purification period, but the damage to the grass carp continued. Furthermore, our investigation unveiled a significant association between the top 20 abundant genera and biomarkers of energy metabolism, providing further insights into the intricate interplay of the microbial-gut-liver axis. Concurrently, we detected 6 common quinolone resistance genes in the experimental group, indicating a potential risk of antimicrobial resistance genes (ARGs) transmission, which could lead to environmental pollution and pose threats to human health.

Tralopyril is a known endocrine-disrupting chemical that interferes with the thyroid hormone system. Using Oryzias melastigma, we established a full life-cycle exposure and multigenerational model (F0-F3) to investigate the reproductive and skeletal toxicity of tralopyril. Results showed disrupted gonadal maturation, abnormal sex hormone levels, and altered expression of HPG axis genes, with sex-specific feedback patterns. Collagen accumulation and activation of cathepsin K indicated transgenerational bone matrix imbalance. In F1-F2 larvae, downregulation of bmp4 and col2a1a was associated with craniofacial skeletal deformities and delayed mineralization. Fluctuations in thyroid hormone levels and upregulation of tsh beta were linked to bone toxicity, whereas increased er beta expression suggested estrogen-mediated skeletal effects. Parental hormone profiles showed strong correlations with offspring bone phenotypes, indicating multigenerational endocrine disruption. Additionally, abnormal tissue iron and glutathione levels, together with increased fth1 expression, suggested that ferroptosis contributed to multigenerational toxicity. These findings highlight tralopyril's persistent ecological risks, emphasizing the need for regulatory focus on emerging pollutants.

Nickel (Ni) released from olivine weathering during ocean alkalinity enhancement (OAE) may threaten the carbon sequestration capacity of nearshore primary producers. Here, the holobiont of Gracilariopsis lemaneiformis was exposed to a Ni gradient (20-200 μg/L) for 15 days to simulate near-field exposure, combined with 16S rRNA sequencing and targeted metabolomics, to investigate the effects of Ni stress on algal-bacterial carbon metabolism and its light-dark dependent responses.Ni exposure disrupted carbon fixation through altered energy acquisition, metabolic allocation, and growth accumulation, with clear diurnal differences. During the light period, Ni stress mainly induced photodamage, including pigment degradation and impaired photosystem II (PSII) function, thereby limiting ATP and NADPH supply. In contrast, the dark period was characterized by metabolic repair, with enhanced glycolysis, tricarboxylic acid (TCA) cycle, and pentose phosphate pathway (PPP), accompanied by increased α-ketoglutarate and succinate accumulation to maintain energy homeostasis. Meanwhile, the associated microbial community shifted from a "photosynthetic compensation" state to a "tolerance-adaptation" state. Overall, Ni stress disturbed carbon metabolism through a diurnal "daytime photodamage-nighttime metabolic repair" mechanism, potentially affecting the carbon accumulation capacity of G. lemaneiformis. These findings provide new insights into circadian-regulated algal-microbial responses to Ni stress and contribute to ecological risk assessment of OAE in nearshore environments.

Nanoplastics are widely distributed in diverse aquatic environments and pose potential threats to organisms. Despite the growing awareness of nanoplastics' toxicity, their effects on higher-order cognitive functions and ecological adaptability of fish remain poorly understood. This study investigated the effects of 50 nm polystyrene nanoplastics on the cognition and adaptability of marine medaka (Oryzias melastigma) and further explored potential molecular mechanisms through transcriptomic analyses. Exposed fish showed a pattern of faster decision-making but lower accuracy in spatial and numerical learning tasks, indicating reduced cognitive abilities. Exposed fish displayed closer inter-individual distances, increased avoidance distances, and more substantial reliance on shelters in mesocosm systems. Transcriptomic analysis also revealed altered expression of genes involved in cell adhesion, signal transduction, and oxidative stress, especially in focal adhesion and tight junction pathways. This study provides additional neurobehavioral toxicological evidence of nanoplastics and highlights the importance of including nanoplastics in the current plastic management strategies.

Bivalve aquaculture shows promise as a carbon sink, but its sensitivity to temperature and pH fluctuations highlights the need to study the effects of ocean acidification (OA) and ocean warming (OW) on carbon sequestration. This study investigates the effects of OA and OW on physiological processes and carbon sequestration mediated by biosynthesis and biodeposition in Crassostrea gigas. OA significantly enhances carbon ingestion, reduces respiratory carbon, increases carbon allocation to growth, improves digestive efficiency, and promotes TOC accumulation in soft tissues (all p < 0.05). While OW significantly increases excreted and fecal carbon (p < 0.05), but enhanced digestion compensates for energy loss, sustaining TOC accumulation. Combined OA and OW significantly altered soft tissue carbon sequestration, with values between OA and OW alone (p < 0.05). Notably, their interaction increases biodeposit density and sinking velocity (p < 0.05), potentially enhancing carbon burial. Tissue-specific metabolic responses reveal that muscle tissue prioritizes energy production, whereas the digestive gland follows an opposite trend, resulting in uneven energy distribution. Furthermore, functional predictions based on KEGG pathway analysis and correlation patterns suggest that SCFAs production via tryptophan metabolism might be a potential mechanism through which probiotics modulate host metabolism and contribute to biosynthesis-mediated carbon sequestration. However, disruptions in microbial homeostasis due to an imbalance between probiotics and pathogens in the digestive gland may threaten the long-term sustainability of this sequestration process. These findings provide insights into the complex physiological and microbial responses of oysters under climate change, highlighting potential mechanisms for carbon sequestration in marine ecosystems.

Tralopyril, a novel antifouling agent widely used in hull coatings, has raised ecological concerns due to its increasing application. This study employed marine medaka as a model to systematically evaluate the behavioral toxicity and underlying mechanisms of tralopyril exposure. Tralopyril significantly reduced locomotor activity, enhanced phototaxis, and impaired olfactory function. Histopathological analysis revealed damage in multiple organs, including retinal thinning, olfactory epithelial disruption, brain vacuolization, cardiac atrophy, muscle disorganization, and cranial cartilage contraction. At the molecular level, tralopyril altered the expression of key retinal development genes (rh1 (rhodopsin 1), rh2 (rhodopsin 2), six6 (SIX homeobox 6), pax6 (paired box 6), and rx3 (retina and anterior neural fold homeobox 3)), suppressed olfactory receptor expression, and interfered with signal transduction. It also disrupted bone remodeling by affecting osteogenic and osteoclastic processes. Endocrine disruption was evident, with elevated T3 and T4 levels and upregulation of tsh (thyroid-stimulating hormone) and tpo (thyroid peroxidase). Overall, the observed behavioral toxicity is a cumulative consequence of damage to the sensory, neural, cardiac, and skeletal systems, as well as disruptions in multiple molecular pathways including thyroid hormone signaling, olfactory signal transduction, and bone metabolism. This study highlights the multi-organ toxic effects of tralopyril on behaviors in marine fish and provides evidence for the environmental risk assessment of emerging antifouling agents.

Exposure to carbon nanotubes may hinder animal growth. Gut microbiota is closely associated with lipid metabolism in animals, yet its role in the growth impairment of fish induced by carbon nanotubes remains unclear. In this study, juvenile goldfish (Carassius auratus) was exposed to 0-1000 μg/L carboxylated multi-walled carbon nanotubes (MWCNT-COOH) for four weeks to find the correlations between gut microbial community and the induced toxicities. MWCNT-COOH was found to induce histopathological and oxidative damages to liver. The weight of fish body and liver decreased after the MWCNT-COOH exposure at any dose after 14 days (p < 0.05). Pyrosequencing of 16S rRNA gene amplicon showed the MWCNT-COOH exposure greatly disturbed gut microbial community of the fish by increasing the relative abundance of Bacteroidetes phylum and Bacteroides genus and inhibiting Proteobacteria and Firmicutes phyla and Vibrio genus. Correlation and network analyses consistently indicated that the liver weight and body weight changes were positively correlated with the alterations of Firmicutes/Bacteroidetes ratio and negatively correlated with the increase of Bacteroidetes and Bacteroides abundance. Our results suggested that MWCNT-COOH inhibited fish growth by modulating the intestinal microbiota and subsequently disturbing the lipid metabolism.

With industrialization, global climate change has intensified. Ocean alkalinization via olivine addition enhances seawater alkalinity and carbon sequestration but its ecological risks remain poorly understood. In this study, Chlorella vulgaris and Brachionus plicatilis were used as model organisms. Olivine of different particle sizes (≤38 μm, 50-74 μm, ≥154 μm) and dosages (1‰, 2‰) was applied in laboratory experiments with molecular analyses and model evaluation to assess effects on planktonic ecosystems and carbon sequestration. Results indicate strong particle-size dependence, with finer particles causing more pronounced effects. In phytoplankton, small particles induced stronger growth inhibition and reduced photosynthesis, while larger particles showed weaker effects or slight stimulation. In rotifers, fine particles decreased locomotion, feeding, and carbon transfer fluxes, suggesting potential disruption of zooplankton-mediated carbon transport. Overall, particle size, together with suspension characteristics and mineral dissolution processes, likely governs planktonic responses, with suspended fine particles representing a major ecological risk source. Model evaluation further indicates that, under the experimental conditions and assessment framework of this study, larger olivine particles (≥150 μm) exhibited relatively lower ecological risk. However, practical ocean alkalinization applications should balance settling behavior, dissolution efficiency, carbon sequestration, and ecological impacts to optimize the trade-off between carbon removal and ecosystem safety.

Tralopyril is an emerging antifouling biocide widely used in hull coatings. However, tralopyril is neurotoxic and a potential olfactory toxicant. Additionally, it is not easily biodegradable and poses a threat to nontarget aquatic organisms. In this study, marine medaka were exposed to environmentally relevant concentrations of tralopyril from the embryonic stage for 180 days. Olfactory behavior was assessed, and histopathological damage to the olfactory epithelium, olfactory bulb, and brain was observed. The results showed impaired olfactory behavior, thickening of the olfactory epithelium, and an increase in damaged cells and tissue vacuolation in both the olfactory bulb and brain. Measurement of cAMP levels, ion channel protein activity, and related gene expression in the olfactory epithelium indicated disruption of the olfactory signal transduction pathway. Further proteomic analysis of the brain revealed abnormalities in the complement and coagulation cascades, with a significant inhibition of the complement alternative pathway. Brain neurotransmitter-targeted metabolomics showed abnormalities in dopamine synthesis and metabolism, with a significant reduction in dopamine content. ELISA analysis also confirmed decreased C3 and dopamine levels in the olfactory epithelium. Finally, supplementation with exogenous LPS partially restored olfactory function, suggesting that the complement alternative pathway and dopamine synthesis/metabolism are potential mechanisms underlying tralopyril-induced olfactory toxicity.

Ocean acidification (OA) and microplastics (MPs, <5 mm) are co-occurring stressors that threaten marine ecosystems. Although the marine environment contains multiple pollutants, OA can alter the environmental behavior of MPs, influencing their toxicity and environmental fate. Therefore, investigating the interactive effects of OA and MPs is essential. Fish can activate physiological compensatory mechanisms to adapt to OA; however, it remains unclear how MPs affect these mechanisms. In this study, marine medaka were exposed to acidified seawater (pH 7.70) containing environmentally relevant concentrations of MPs (0.1 mg/L) for 90 days to investigate the disruptive effects of MPs on responses to OA. The results showed that while OA triggered compensatory energy metabolism reprogramming to enhance ammonia production, MPs disrupted this process, reducing the TCA cycle intermediate α-ketoglutarate. This α-ketoglutarate deficiency limited the glutamate supply for ammonia production. Simultaneous inhibition of glutamate dehydrogenase activity further limited glutamate availability. As a result, MPs reduced the level of ammonia production by 25.29%, compromising the ability to neutralize excess H+. Crucially, photoaging exacerbated this toxicity, leading to a 32.04% reduction in ammonia production. This study demonstrates that MPs interfere with fish responses to OA via α-ketoglutarate-mediated metabolic reprogramming, highlighting a vulnerability in marine organisms facing climate change scenarios.

The co-application of biochar and organic fertilizer with chemical fertilizer is considered an important strategy for improving soil functions and vegetable quality. In this study, a field experiment was conducted with four treatments under equal total nutrient input: chemical fertilizer alone (T1), 50% substitution of chemical fertilizer nutrients with organic manure (T2), chemical fertilizer plus biochar (T3), and 50% substitution of chemical fertilizer nutrients with organic manure plus biochar (T4). The objective of this study was to investigate the effects of organic fertilizer and biochar application on lettuce yield, soil physicochemical properties, and leaf metabolomic profiles, thereby providing a scientific foundation for reducing chemical fertilizer inputs, enhancing fertilizer use efficiency, and improving vegetable quality. The results showed that, compared with T1, treatments T2, T3, and T4 increased soil organic matter, pH, available nitrogen, phosphorus, and potassium contents, as well as lettuce yield and nutrient uptake to varying degrees, with T4 exhibiting the most pronounced overall effects. Metabolomic analysis revealed that the application of organic fertilizer and biochar significantly up-regulated phenolic acids and flavonoids in lettuce leaves and promoted the enrichment of pathways associated with secondary metabolite accumulation, such as phenolic acid biosynthesis and sulfur metabolism. Correlation analysis further indicated that the changes in leaf metabolites were significantly correlated mainly with soil organic matter, pH, and available potassium. KEGG enrichment analysis uncovered differential impacts of the fertilization treatments on metabolic pathways: organic fertilizer primarily affected the tyrosine metabolism pathway, biochar mainly influenced nitrogen metabolism-related pathways (involving zeatin and amino acids), whereas the combination of organic fertilizer and biochar predominantly affected pathways including phenolic acid biosynthesis and sulfur metabolism. In conclusion, from a metabolomics perspective, this study revealed the metabolic pathway division of labor and synergistic effects of organic fertilizer and biochar in regulating secondary metabolism in lettuce, and preliminarily established associations between soil physicochemical factors and leaf metabolites, providing new insights into the quality improvement mechanism of organic substitution combined with biochar.

The integrity of the fish visual system is a critical indicator of aquatic environmental health. However, the etiology of pollutant-induced visual impairment remains fragmented, and the impairment is rarely localized. To map the evolving landscape of this field, we first conducted a bibliometric analysis, which reveals a paradigm shift from initial phenomenological observations to complex mechanistic exploration. Informed by the key trends and knowledge gaps identified in this analysis, we then critically integrate the core pathological mechanisms of visual dysfunction: direct ocular toxicity and indirect cascading effects driven by cross-system interactions. For precise environmental monitoring, we synthesize diagnostic biomarkers specifically linked to these distinct toxicological mechanisms, providing a strategic framework for endpoint selection. Within this complex interaction landscape, we identify the gut-retina axis as a primary regulatory target in mediating visual toxicity. We provide a detailed examination of how pollutant-induced gut dysbiosis triggers systemic inflammation and alters metabolic signaling. By integrating these multidimensional findings, we propose a conceptual Adverse Outcome Pathway (AOP) framework. Distinct from traditional ocular-centric AOPs that focus on direct tissue damage, this AOP integrates cross-system signaling in the chain from gut dysbiosis to retinal neurotoxicity. This review provides a theoretical basis for understanding pollutant-induced visual dysfunction and offers an AOP-informed conceptual perspective for hypothesis generation and future ecotoxicological risk assessment in aquaculture ecosystems.

The extensive use of antibiotics, particularly sulfadiazine (SDZ), has led to significant environmental contamination and the proliferation of antibiotic resistance genes (ARGs). This study investigates the bioremediation potential of two SDZ-degrading bacterial strains, Acinetobacter sp. M9 and Enterobacter sp. H1, and their impact on ryegrass (Lolium perenne) growth and the inter-root microenvironment in SDZ-contaminated soils. A pot experiment combined with amplicon and metagenomic sequencing revealed that inoculation with M9 and H1 significantly enhanced ryegrass growth by alleviating oxidative stress, increasing chlorophyll content, and improving soil nutrient availability. The strains also promoted SDZ degradation efficiency and improved carbon and nitrogen cycling through the upregulation of key functional genes. Furthermore, microbial community analysis demonstrated increased alpha diversity, shifts in dominant taxa, and functional enrichment in pollutant degradation pathways. The dynamics of ARGs revealed a decrease in aminoglycoside, rifamycin, and streptomycin resistance genes, while sulfonamide resistance genes increased due to the residual SDZ stress. These findings highlight the potential of M9 and H1 as sustainable bioremediation agents to mitigate antibiotic contamination, improve soil health, and support plant growth in polluted environments.

The urgency of emerging pollutants driven by human activities presents an increasing threat to the health of fish. The mucosal system, serving as a primary barrier against environmental pollutants, has emerged as a central focus in toxicological research. Alterations in the mucosal microbiota can impact health at both local and systemic levels. This review explores the toxic effects of emerging pollutants on the mucosal immunity of teleost fish, reflects on the reasons behind the limited focus on adaptive immunity studies, and highlights changes in microbial composition, gene expression, histology, and overall mucosal organ function. Furthermore, we summarize the mechanisms through which these pollutants disrupt the mucosal barriers of teleosts, emphasizing interactions between the mucosal microbiota, physical barriers, and immune defenses. The relevant methodologies and potential solutions to the current challenges have been summarized. While current research predominantly centers on the intestines and gills, further studies are needed to investigate the toxic effects of emerging pollutants on other mucosal organs and to elucidate how microbiota influence host health through neuro-immune communication. This review aims to provide a comprehensive overview of mucosal immunity, serving as a theoretical foundation for the assessment of related ecological risks.

Bisphenols, a class of compounds with endocrine-disrupting characteristics, encompassing its effects on reproduction, nervous and immune systems. Diet represents the principal route of bisphenols intake, prompting concerns about dietary exposure. In this study, the occurrence and content of nine bisphenols in 96 marine shrimps from Tianjin were detected and analysed using ultra high performance liquid chromatography mass spectrometer and solid-phase extraction. The analytical method was validated to demonstrate reliable analytical performance. The results revealed that bisphenol A was detected in the majority of the samples, with the highest detection rate among the nine bisphenols, followed by bisphenol S, while the remaining bisphenols were not detected. A discernible age-related trend was identified in the assessment of dietary exposure, whereby exposure levels increased with decreasing age. Furthermore, regional discrepancies were observed, yet no gender-based distinctions were discerned. The estimated daily intake to total bisphenols through marine shrimp in this study was lower than the current tolerable daily intake set by the European Food Safety Authority, and it can be assumed that the risk of exposure to the nine bisphenols investigated through dietary is acceptable. However, given the recently proposed draft values by the European Food Safety Authority and the higher exposures observed in children and teenagers, further surveillance and dietary guidance is required. To our knowledge, this is the first study in Tianjin to evaluate the health risks associated with bisphenol A and its analogues via marine shrimp, which can monitor dietary safety and protect population health.

Enrofloxacin (ENR), commonly used in aquaculture, plays a role in the development and dissemination of antibiotic resistance genes (ARGs). While most research on ARGs has focused on the environment, the gut, the host’s largest microbial habitat, remains underexplored. Accordingly, this research investigates the gut microbiome, aiming to assess the potential mobility of ARGs after ENR exposure. Additionally, ENR exposure alters short-chain fatty acid (SCFAs) levels. Subsequent conjugation transfer experiments demonstrated that ENR exposure modifies SCFA levels, and this alteration facilitates the spread of ARGs. Both plasmid- and phage-mediated ARGs transmission were observed. ENR exerted selective pressure on the gut microbiota, significantly promoting plasmid-mediated conjugation as a key driver of ARGs dissemination. Simultaneously, environmental stress triggered the release of progeny phages carrying ARGs, further facilitating their spread. Conjugation experiments confirmed that ENR and SCFAs interact with bacterial outer membrane proteins, inducing the production of ROS. As a result of ROS production, membrane integrity is disrupted and membrane permeability is increased, ultimately causing an increase in the frequency of conjugative transfer and facilitating the horizontal delivery of ARGs. Therefore, ENR not only directly influences the transmission of ARGs but also indirectly promotes their transmission by altering SCFA levels. The study findings underscore the risks posed by excessive use of ENR in aquaculture to public health, providing scientific evidence to prevent food safety hazards from market entry of aquatic products carrying drug-resistant pathogens.

According to the "2024 Global Carbon Budget" report, emission reduction alone is insufficient to avert the dual crises of ocean acidification and climate change. As a result, negative ocean emissions-particularly alkalinity enhancement-have gained scientific attention as promising carbon sequestration strategies. This paper examines research on negative marine emissions by analyzing the structure and functioning of aquatic ecosystems. A comprehensive analysis of studies sourced from the China National Knowledge Infrastructure (CNKI) and Web of Science (WOS) databases was conducted to assess the impact of alkalinity enhancement sinks on marine systems. Various species and environmental factors were considered in the investigation. Furthermore, preliminary estimates of the carbon sink capacity of shellfish-algae systems were provided for nine coastal provinces of China and across six continents, concerning oceanic pH levels. By summarizing the current state of research on negative global ocean emissions, this review aims to evaluate the potential risks and synergistic benefits associated with the alkalinity enhancement sinks to advance the science in this area and lay the groundwork for future research.

Micro- and nanoplastics (MNPs) form protein corona (PC) upon contact with biological fluids, but their impact on the intracellular transport, distribution, and toxicity of MNPs remains unclear. Fetal bovine serum (FBS) and bovine serum albumin (BSA) were used to simulate in vivo environment, this study explored their influence on the transport and toxicity of polystyrene (PS) MNPs in zebrafish liver (ZFL) cells. Results showed PS MNPs were wrapped by proteins into stable complexes. Nanoparticles (NP, 50 nm) and their protein complexes (NP@PC) were internalized by cells within 6 h, with PC formation enhancing NP uptake. NP primarily entered cells through clathrin- and caveolae-mediated endocytosis, while NP@PC via clathrin-mediated pathways. Internalized particles were predominantly in lysosomes where PC degraded and some were also in mitochondria. Eventually, particles were expelled from cells through energy-dependent lysosomal pathways and energyindependent membrane penetration mechanisms. Notably, PC formation limited the clearance of NP. In toxicity, NP had a more severe impact than microplastics (MP, 5 mu m). FBS more effectively mitigated PS MNPsinduced reactive oxygen species accumulation, subcellular structural damage, and dysregulation of glycolipid metabolism than BSA did. This study elucidates the modulatory role of PC on biological effects of MNPs, providing safety and risk management strategies.