Marine Environmental Research[JOURNAL]
Sun
200 papers
Impact of low oxygen in diatom Nitzschia in light and dark conditions.
Vijayan NT, Gauns MU, Pratihary AK
Mar Environ Res · 2026 Jun · PMID 42269306 · Publisher ↗
Rising ocean temperatures is a major concern as it intensifies deoxygenation, threatening marine life and biogeochemical cycles. The lowering oxygen concentration can impact phytoplankton, a key primary producer reliant...
Rising ocean temperatures is a major concern as it intensifies deoxygenation, threatening marine life and biogeochemical cycles. The lowering oxygen concentration can impact phytoplankton, a key primary producer reliant on O for respiration, affecting marine productivity, fisheries, and food webs. Here, we examined how lowering oxygen concentration (hypoxia, anoxia) affect pennate diatom Nitzschia sp. under dim-light (∼20 μmol photons m s) and dark conditions using isolates from anoxic benthic waters of the Western Indian Continental Shelf (WICS), the world's largest coastal hypoxic zone. In the in vitro experiment conducted under dim light, diatom growth decreased as O concentration decreased, with lower growth rates under hypoxic (0.21 day) and anoxic (0.24 day) conditions compared to normoxic conditions (0.32 day). While in the dark, diatom growth rates were lower compared to light under oxic (0.06 day), hypoxic (0.10 day), and anoxic (0.10 day) conditions; however, cells remained viable under all lower oxygen conditions. Interestingly, under dark conditions, the highest nitrate uptake was observed under anoxic conditions (53 pmol cell day), compared to oxic conditions (42 pmol cell day; 82%). While, under 12 h light: 12 h dark incubation conditions, nitrate uptake was lower in oxic- L:D (6.9 pmol cell day) and anoxic- L:D (5.9 pmol cell day) conditions. The intracellularly stored nitrate (ICNO) was consumed only under anoxic-D conditions (0.3 pmol cell day), compared to oxic-dark, anoxic-L:D and oxic-L:D, suggested the enhanced ICNO utilization in the dark-anoxic condition. Similarly, higher NO uptake in antibiotic-treated (AT-Nitzschia, 39%) and antibiotic-untreated (UT-Nitzschia, 56%) cultures, with higher ICNO consumption (AT-Nitzschia, 84%; UT-Nitzschia, 69%) and increased extracellular ammonium (ECNH) indicated diatom-mediated nitrate utilization under anoxic-dark condition.
Ontogenetic and spatial variation in the feeding habits of Tripneustes gratilla.
Liu Z, Zhao X, Guo Y … +1 more , Qin C
Mar Environ Res · 2026 Jun · PMID 42263421 · Publisher ↗
As a keystone species in coral reef ecosystems, the collector sea urchin Tripneustes gratilla maintains its ecological balance by regulating algal populations; however, a systematic understanding of its role as a primary...
As a keystone species in coral reef ecosystems, the collector sea urchin Tripneustes gratilla maintains its ecological balance by regulating algal populations; however, a systematic understanding of its role as a primary consumer in tropical marine environments remains limited. In this study, we investigated T. gratilla populations in coastal waters near Wuzhizhou Island, Sanya city, Hainan Province, China. Using 18S rDNA and 16S rDNA high-throughput sequencing, we analyzed differences in the T. gratilla diet in autumn across different habitats and body size classes. The analysis revealed that Tripneustes gratilla has a diverse diet spanning multiple phyla, including Arthropoda, Rhodophyta, Apicomplexa, and Cyanobacteriota. Distinct spatial dietary patterns were observed across different benthic habitats. In offshore rocky substrates, the gut contents primarily consisted of Rhodophyta (red algae) and Arthropoda (crustaceans), collectively accounting for more than 40% of the ingested material. Conversely, nearshore sandy-gravel substrates showed remarkable dietary specialization, with Arthropoda and Rhodophyta constituting more than 70% of the total dietary composition. Body size influenced the T. gratilla diet: large individuals (500-600 g) consumed specialized diets dominated by Eukaryota and Rhodophyta (>80%), whereas medium and small individuals presented greater dietary diversity. The gut microbiota demonstrated regional universality, with Proteobacteria and Bacteroidetes constituting the core microbiome. Environmental factors (e.g., pH) significantly affect T. gratilla feeding behavior. In this study, we identified habitat heterogeneity and ontogenetic shifts as critical drivers of T. gratilla trophic ecology, providing novel insights into its functional role in ecosystem dynamics.
Light modulates the impact of aluminum on the physiology of the coccolithophore Emiliania huxleyi.
Sun W, Liu Y, Gao L … +4 more , Chen M, Liu J, Liu X, Tong S
Mar Environ Res · 2026 Jun · PMID 42259098 · Publisher ↗
Aluminum (Al) is ubiquitous in marine environments, yet its physiological effects on phytoplankton remain inadequately understood, particularly under variable light regimes. This study investigated the individual and int...
Aluminum (Al) is ubiquitous in marine environments, yet its physiological effects on phytoplankton remain inadequately understood, particularly under variable light regimes. This study investigated the individual and interactive effects of Al and light intensity on the coccolithophore Emiliania huxleyi GY-H55 using a factorial design with three light levels and three Al treatments. Under low light, both low and high Al elevated growth rate by ∼24%. Under medium and high light, low Al had no effect on growth, whereas high Al decreased it. Carbon/nitrogen production rate increased by 12.1-23.3% with both Al additions under low and medium light, likely through improved light harvesting, as indicated by elevated chlorophyll a content. In contrast, under high light, high Al inhibited carbon/nitrogen assimilation, accompanied by suppressed electron transport and impaired non-photochemical quenching, effects likely driven by enhanced oxidative stress, as reflected in elevated malondialdehyde levels. These results demonstrate that the role of Al shifts from beneficial to inhibitory depending on light intensity and concentration. Since most oceanic Al concentrations remain low (tens of nanomoles per liter), we suggest that Al might support phytoplankton productivity under current and projected surface light conditions, with potential implications for ocean productivity in a changing climate. It should be noted that the strain used here had lost its calcifying capacity, a limitation that future studies should address to fully understand the integrated response of E. huxleyi to Al and light.
Linking hydrocarbon gradients to microbial community variation across full-depth water columns in the Western Pacific Ocean.
Jiang L, Chen C, Hu S … +6 more , Jiang L, Zhang D, Ji Z, Zhang C, Xiong L, Zhou H
Mar Environ Res · 2026 Jun · PMID 42259097 · Publisher ↗
Hydrocarbons are widely distributed in marine environments and may influence microbial communities even at the low concentrations typically found in non-contaminated marine environments, yet their vertical patterns and e...
Hydrocarbons are widely distributed in marine environments and may influence microbial communities even at the low concentrations typically found in non-contaminated marine environments, yet their vertical patterns and ecological implications in oligotrophic open-ocean systems remain poorly understood. In this study, we investigated six full-depth pelagic water-column profiles (maximum depths ranging from 1000 m to 5900 m) in the Western Pacific Ocean, integrating measurements of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) with microbial community composition, diversity, and assembly analyses across 44 samples. The results showed that n-alkanes exhibited clear depth-related enrichment, particularly for long-chain homologues, likely associated with particle-mediated transport, whereas PAHs displayed more variable vertical patterns influenced by multiple processes. Molecular diagnostic indices indicated predominantly pyrogenic sources, suggesting potential transformation during vertical transport. Hydrocarbon gradients were associated with shifts in microbial community composition and diversity, accompanied by changes in predicted functional potential, with higher concentrations favoring hydrocarbon-associated and heterotrophic taxa. Moreover, community assembly analysis indicated that hydrocarbon variability governed niche-based transitions in microbial communities; elevated concentrations decoupled microbial taxa from their environmental niches, shifting the assembly processes from dispersal limitation to drift dominance. This transition was further supported by a structural simplification of co-occurrence networks, characterized by reduced connectivity and complexity under hydrocarbon pressure. These findings suggest that even background hydrocarbon variability may influence microbial community organization and assembly in oligotrophic marine environments. Overall, this study provides new insights into how natural hydrocarbon variability may shape microbial community organization and assembly processes in oligotrophic open-ocean ecosystems.
Temporal and spatial changes in fish assemblages associated with the placement of a rock armoured pipeline complex in northwestern Australia.
Marshall BT, Harvey ES, Elsdon TS … +5 more , Marnane MJ, de Lestang P, Jones C, Wiegele K, Saunders BJ
Mar Environ Res · 2026 Jun · PMID 42259096 · Publisher ↗
Despite growing knowledge of the effects of subsea pipelines for fishes, the influences of their associated protective structures, such as rock armour used for stabilisation, on fish assemblages remain understudied. We u...
Despite growing knowledge of the effects of subsea pipelines for fishes, the influences of their associated protective structures, such as rock armour used for stabilisation, on fish assemblages remain understudied. We used baited remote underwater stereo-video systems (stereo-BRUVs) to assess how fish assemblage composition, biomass, and the number of species and individuals changed in response to the placement of a rock armoured pipeline complex within soft sediment habitat in northwestern Australia. We compared fish assemblage metrics before placement to those observed one, two, and eleven years after, and how responses varied with distance from the rock armour habitat. A total of 239 unique identifiable taxa were observed across all samples, 40 of which were unique to samples within or close to the rock armour habitat. Fish assemblages exhibited a strong but spatially limited response to the presence of the rock armour habitat, with a distinct assemblage composition characterised by reef-associated species and increases in fish abundance, biomass and the number of species observed within 30 m of the rock armouring following its placement. We demonstrate the potential ecological role of rock armouring as an artificial reef habitat for fishes and highlight the importance of having longer-term studies when assessing the impacts of artificial structures.
Picophytoplankton dominance driven by multi-factor eutrophication in a subtropical mariculture bay.
Wang JX, Kong FZ, Liu C … +3 more , Geng HX, Kang ZJ, Yu RC
Mar Environ Res · 2026 Jun · PMID 42251770 · Publisher ↗
Under the influence of anthropogenic activities, phytoplankton communities in coastal oceans have undergone significant alterations. Qinzhou Bay (QB), a typical subtropical mariculture bay, has experienced rapid developm...
Under the influence of anthropogenic activities, phytoplankton communities in coastal oceans have undergone significant alterations. Qinzhou Bay (QB), a typical subtropical mariculture bay, has experienced rapid development of oyster mariculture industry and notable eutrophication, yet the systematic dynamics of phytoplankton communities and their driving mechanisms remain poorly characterized. In this study, monthly investigations were conducted from November 2021 to November 2022 to obtain physical, chemical, and phytoplankton data. The size structure, taxonomic composition, and spatiotemporal dynamics of phytoplankton assemblages were systematically analyzed using flow cytometry, pigment analysis, and high-throughput amplicon sequencing. Phytoplankton assemblages exhibited distinct spatial rather than temporal variability during the study period. The low-salinity eutrophic inner bay showed signs of phytoplankton miniaturization, with pico-sized prasinophytes and chlorophytes as characteristic taxa, whereas the nutrient-poor outer bay was dominated by relatively larger diatoms and dinoflagellates. Partial least squares regression (PLS-R) analysis identified phosphate (the most important), dissolved oxygen, temperature, salinity, and ammonium as the key environmental drivers shaping phytoplankton assemblages. Causal analysis based on partial least squares path modeling (PLS-PM) further demonstrated that nutrient status was the primary factor driving changes in phytoplankton size structure and taxonomic composition. Physical conditions and oyster aquaculture (via phosphate excretion) indirectly regulated phytoplankton assemblages mainly by modulating the nutrient regime in QB. Oyster grazing exerted a minor direct effect on phytoplankton size structure but substantially reduced phytoplankton biomass. Overall, the multi-factor eutrophication has promoted phytoplankton miniaturization in QB, raising concerns about potential food web imbalance and the risk of future pico-sized harmful algal blooms.
Corrigendum to "Kelp forests as natural barriers against invasive turf-forming algae" [Mar. Environ. Res. 220 (2026) 108160].
Alvite N, Barrientos S, Barreiro R … +1 more , Piñeiro-Corbeira C
Mar Environ Res · 2026 Jun · PMID 42250998 · Publisher ↗
Abstract loading — click title to view on PubMed.
Microplastics alter the toxicity of benzo[a]pyrene in a mangrove oyster: An integrated biomarker approach.
Giannetto RVG, Barbosa Dos Santos J, Choueri RB … +6 more , Carnaúba JH, Cecilia Rizzatti de Albergaria-Barbosa A, Simões FR, Pereira CDS, Nobre CR, Kachel Gusso-Choueri P
Mar Environ Res · 2026 Jun · PMID 42250519 · Publisher ↗
Microplastics (MPs) and Benzo[a]pyrene (BaP) are ubiquitous co-contaminants in marine environments, yet their combined ecotoxicological effects remain poorly understood. This study evaluated the isolated and interactive...
Microplastics (MPs) and Benzo[a]pyrene (BaP) are ubiquitous co-contaminants in marine environments, yet their combined ecotoxicological effects remain poorly understood. This study evaluated the isolated and interactive toxicity of alone linear low-density polyethylene (LLDPE) (0, 5, 50, 500 mg L) and BaP (0, 3, 12, 21, 30 μg L) in the mangrove oyster Crassostrea gasar, a key filter-feeding species highly vulnerable to particulate and hydrophobic contaminants. The concentrations of 5 mg/L MPs and all BaP concentrations tested are environmentally relevant. Adult oysters were exposed for 7 days in a full factorial design, and biomarkers (Glutathione S-transferase, Glutathione Peroxidase, Reduced Glutathione, Lipid Peroxidation, DNA damage, Neutral Red Retention Time) were assessed in gills and hemolymph. Alone MPs alone induced oxidative and cytogenotoxic effects, confirming that even uncontaminated plastic particles can disrupt cellular homeostasis. Significant interactive effects between MPs and BaP were observed, particularly influencing oxidative stress and DNA integrity. GPx, GST, and GSH responses were associated with DNA damage at higher exposure levels. BaP increased lipid peroxidation, reducing lysosomal membrane stability, and this impairment was exacerbated under combined exposure. The integrated biomarker response index identified the combination of 30 μg L BaP and 500 mg L MP as the most hazardous scenario. The environmentally relevant MP concentration (5 mg L) also produced significant effects when combined with BaP. These findings demonstrate that MPs modulate BaP toxicity and highlight the importance of assessing co-contaminant interactions in filter-feeding organisms. Although the highest concentration tested (500 mg L) exceeds environmental levels, effects were also observed at environmentally relevant concentrations. The inclusion of elevated concentrations was intended to identify effect thresholds and underlying mechanisms, providing robust data for environmental risk assessment.
Preliminary evidence of intra-offshore wind farm variation in epibiotic assemblages from automated ROV image analysis.
Marlow J, Halpin JE, Wilding TA
Mar Environ Res · 2026 Jun · PMID 42248059 · Publisher ↗
As global energy demand grows, our oceans are becoming increasingly industrialised. In the North Sea, one of the world's most developed marine regions, offshore infrastructure is shifting from isolated hydrocarbon platfo...
As global energy demand grows, our oceans are becoming increasingly industrialised. In the North Sea, one of the world's most developed marine regions, offshore infrastructure is shifting from isolated hydrocarbon platforms to large multi-turbine offshore wind farms (OWFs). These structures support diverse epibiotic assemblages which can influence structural integrity, alter ecological processes, and affect ecosystem service provisioning (e.g. water filtration). While epibiotic assemblage composition and zonation is well characterised on solitary structures, little is known about this varies at the intra-OWF scale. Our study explores this variation using ROV footage from a UK OWF; the foundations of two jacketed turbines situated at both the edge and centre of the OWF footprint were surveyed across all legs and depths, and the cover of five dominant epibenthic taxa quantified using a combination of structure-from-motion photogrammetry and machine-learning-based taxonomic segmentation. Epibiotic assemblages were dominated by anemones (Metridium senile) at intermediate depths, with increasing abundance of other target taxa at greater depths. While depth was the primary structuring factor, assemblage composition also appeared to vary with cardinal orientation and turbine position, with higher coverage of most target taxa at the OWF centre (notably soft corals (Alcyonium digitatum)). These patterns may be influenced by turbine-induced changes in downstream turbulence, stratification, and resource availability. While a limited sample size, our results suggest intra-OWF epibiotic heterogeneity, implying assemblage structure varies beyond depth zonation. As offshore wind development accelerates, research is needed to determine this variability's extent and drivers, helping to manage the consequences of an industrialised seascape.
Emission and enrichment of coastal viable and non-viable bacteria during ocean-atmosphere transfer.
Feng Y, Zhang Y, Ruan Z … +4 more , Duan B, Wu L, Tham YJ, Lai S
Mar Environ Res · 2026 May · PMID 42248058 · Publisher ↗
Airborne bacteria significantly influence the environment, climate, and public health. The nature and extent of these impacts, however, can vary depending on bacterial viability. To understand the sources and controlling...
Airborne bacteria significantly influence the environment, climate, and public health. The nature and extent of these impacts, however, can vary depending on bacterial viability. To understand the sources and controlling factors of viable and non-viable bacteria in coastal aerosols, we investigated their temporal variations, cell size distributions, and enrichment during sea-to-air transfer at Wanshan Island, southern China. Viable bacteria in aerosols showed strong correlations with those in seawater in both concentration (r = 0.783) and cell size distribution, indicating a dominant seawater origin. Their emission was jointly enhanced by seawater viable bacterial abundance and chlorophyll a (r = 0.910). In contrast, non-viable bacteria showed no such correlation and exhibited distinct size patterns, and were primarily influenced by rainfall, sea surface temperature, and relative humidity, suggesting they are controlled by atmospheric physical processes. During sea-to-air transfer, viable bacteria were preferentially enriched with an enrichment factor of 236 compared to non-viable bacteria (143). Although viable bacteria account for only 13% of total bacteria in seawater, their contribution to the emission flux rises to approximately 20% (18.4 cells m s). The estimated viable bacterial productivity flux is 2.3 × 10 g C m d. Given the higher enrichment of viable bacteria in sea spray aerosols, their potential contribution to ice nucleation and cloud condensation processes in coastal regions needs further investigation. These findings highlight the importance of distinguishing between viable and non-viable bacteria in assessing marine microbial impacts on atmospheric chemistry, carbon cycling, and climate.
Mercury concentrations in cephalopods from the Pacific sector of the Southern Ocean in relation to their biology, habitat and trophic position.
Lespinas M, Xavier JC, Bustamante P … +5 more , Queirós JP, Thompson DR, Coelho P, Pereira ME, Seco J
Mar Environ Res · 2026 Jun · PMID 42241962 · Publisher ↗
Mercury (Hg) can negatively affect marine biota through uptake from prey and from the surrounding environment. Cephalopods constitute a major prey group in Southern Ocean ecosystems, yet little is known about Hg concentr...
Mercury (Hg) can negatively affect marine biota through uptake from prey and from the surrounding environment. Cephalopods constitute a major prey group in Southern Ocean ecosystems, yet little is known about Hg concentrations in these taxa and how biological and ecological factors can influence Hg body burdens. By combining stable isotope analyses (δC and δN) and Hg concentrations in beaks from 25 cephalopod species from the Pacific sector of the Southern Ocean, we studied 1) habitats and trophic positions; 2) Hg concentrations; and 3) how Hg concentrations relates to lower rostral length, habitat and trophic position of the studied species. Our results showed that δC values indicated that species inhabited various water masses, with Alluroteuthis antarcticus inhabiting further north than previously reported. Additionally, δN values of these cephalopod species showed that cephalopods in the Pacific sector of the Southern Ocean occupy two to three trophic levels with Hg concentrations among studied cephalopod species increasing from southern to northern habitats. Mercury concentrations in cephalopod beaks ranged from 0.003 μg g (Filippovia knipovitchi) to the highest concentration ever recorded in cephalopod beaks (0.590 μg g in Histioteuthis atlantica), with Hg concentrations increasing with the lower rostral length in H. atlantica but decreasing in Moroteuthopsis ingens. Our results suggest that Hg concentrations in Southern Ocean cephalopods may be driven by species-specific factors rather than a general pattern across species. This study emphasizes the need for cephalopod species-specific research on Hg bioaccumulation and biomagnification to better understand its impact on Southern Ocean marine food webs.
The vital role of epiphytic bacteria in tropical marine macrophytes: community structure differences between macroalgae and seagrass in Hainan Island, China.
Wu Y, Li J, Fu S … +3 more , Luo H, Wang W, Xie S
Mar Environ Res · 2026 Jun · PMID 42241961 · Publisher ↗
Epiphytic bacteria play crucial roles in the ecological and biochemical processes of tropical macroalgae and seagrass, yet comparative studies on their community structure and functional profiles across these distinct ho...
Epiphytic bacteria play crucial roles in the ecological and biochemical processes of tropical macroalgae and seagrass, yet comparative studies on their community structure and functional profiles across these distinct hosts remain limited. Here, we characterized the epiphytic bacterial communities of two macroalgae (Sargassum polycystum, SP; Eucheuma gelatinae, EG) and one seagrass (Enhalus acoroides, EA) from Hainan Island, China, using 16S rRNA high-throughput sequencing, and examined their relationships with environmental factors across the April-June growing season. Host identity was the dominant driver of community structure, independently explaining 52.1% of variation, followed by temporal (32.7%) and environmental (23.2%) components (PERMANOVA R = 0.753). EA harbored significantly higher alpha diversity (Shannon: 6.25 ± 0.16; Chao1: 4064.43 ± 683.15) than SP (Shannon: 4.57 ± 0.81) and EG (Shannon: 4.93 ± 1.25). Kistimonas dominated EG (22.21%) but was nearly absent from other hosts, likely reflecting its specialized degradation of sulfated polysaccharides of EG, whereas Erythrobacter was enriched in EA (5.57%). LEfSe identified 33 biomarkers (14 seawater, 19 marine macrophyte-associated), with only EG showing significant temporal fluctuations (CV of Shannon = 32.7% vs. 4.3% for EA), indicating that host endogenous physiology overrides external environmental variability in governing temporal stability. Environmental factors (temperature, DOC, TN, EC, and Chl-a) exhibited positive correlations with specific genera (Alteromonas, Paraburkholderia, Woeseia, AqS1, Variovorax) but played a secondary, modulating role. Predicted functional profiles were highly conserved across hosts (only 4 of 28 KEGG level-2 pathways differed significantly), suggesting broadly shared core metabolism. These findings underscore the primacy of host traits in structuring tropical epiphytic microbiomes and highlight the need for metatranscriptomic validation of predicted functions.
Mitochondrial uncoupling protein SpUCP regulates redox homeostasis and enhances heavy metal tolerance in mud crab (Scylla paramamosain) exposed to copper and cadmium.
Cheng CH, Fan SG, Ma HL … +5 more , Liu GX, Deng YQ, Jiang JJ, Feng J, Guo ZX
Mar Environ Res · 2026 Jun · PMID 42241960 · Publisher ↗
Heavy metal pollution, particularly copper (Cu) and cadmium (Cd), poses a severe threat to coastal ecosystems and the aquaculture industry of mud crabs (Scylla paramamosain), a commercially important crustacean species....
Heavy metal pollution, particularly copper (Cu) and cadmium (Cd), poses a severe threat to coastal ecosystems and the aquaculture industry of mud crabs (Scylla paramamosain), a commercially important crustacean species. S. paramamosain, a dominant and economically important coastal aquaculture crustacean, is highly sensitive to heavy metal pollution due to its benthic and omnivorous lifestyle, making it an ideal stress-response model. Mitochondrial uncoupling proteins (UCPs) regulate mitochondrial function and oxidative stress, but their roles in mud crabs under heavy metal stress are unknown. This study aimed to clone and characterize a novel mitochondrial uncoupling protein gene from the mud crab, and to clarify its regulatory function in oxidative stress and tolerance under copper and cadmium exposure. In this study, a novel UCP gene was cloned from the mud crab (designated SpUCP). Tissue-specific expression analysis revealed that SpUCP was predominantly expressed in the hepatopancreas and gills. Mud crabs were exposed to different concentrations of Cu (0, 0.1, 0.5, 2.0 mg/L) and Cd (0, 0.1, 0.5, 2.0 mg/L) for 72 h, respectively. The current study revealed that exposure to Cu and Cd led to elevated hydrogen peroxide (HO) accumulation and lipid peroxidation (MDA). while concurrently suppressing the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), suggesting that heavy metals caused oxidative stress and tissue damage. SpUCP expression was elevated in response to both Cu and Cd stressors, suggesting its role in mediating stress resistance in the mud crab. Furthermore, an RNA interference (RNAi) assay was designed to elucidate the functional roles of SpUCP in the mud crab under Cu and Cd stress. SpUCP knockdown in vivo not only significantly diminished SOD and CAT activities post-heavy metal exposure but also enhanced HO generation and elevated mortality rates in mud crabs subjected to Cu and Cd stress, indicating that SpUCP maintains redox balance by reducing mitochondrial reactive oxygen species (ROS) production through mild uncoupling. It was first cloning and functional characterization of a UCP gene in the mud crab, and the first report revealing its protective role against heavy metal toxicity. This study provides novel insights into the molecular mechanisms underlying the tolerance of mud crabs Cu and Cd stress and offers a molecular basis for evaluating coastal heavy metal pollution and a potential target for breeding stress-tolerant mud crab.
Selection and qualification of standard test organisms for BWMS type-approval testing.
Shin J, Cho J, Shin Y … +2 more , Kim H, Heo C
Mar Environ Res · 2026 Jun · PMID 42241959 · Publisher ↗
Seasonal and regional variability of natural plankton assemblages can constrain biological validity in BWMS land-based type-approval testing, particularly when challenge-water concentrations fall below regulatory require...
Seasonal and regional variability of natural plankton assemblages can constrain biological validity in BWMS land-based type-approval testing, particularly when challenge-water concentrations fall below regulatory requirements. This study proposes an evidence-based workflow to select and qualify standard test organisms (STOs) for the ≥10 μm to <50 μm and ≥50 μm size classes. Survivor records from full-scale type-approval tests were first used to prioritize taxa that persist through treatment and subsequent handling. Four candidates were finalized: two centric diatoms for the ≥10 μm to <50 μm class (Stephanocyclus meneghinianus and Actinocyclus sp.) and two zooplankton for the ≥50 μm class (Moina macrocopa and Tigriopus sp.). Taxonomic assignments were supported by DNA barcoding, and regulatory compliance was evaluated using minimum-dimension measurements under practical microscopy views. All candidates consistently satisfied the relevant size thresholds. Operational feasibility was assessed through routine maintenance, showing stable culture growth for diatoms (OD750) and maintained or increasing total abundance for zooplankton. Control-holding performance under test-relevant conditions was examined during short-term dark holding across freshwater, brackish, and marine waters over the protocol temperature range (5-35 °C) for up to 5 days. The ≥10 μm to <50 μm candidates remained above the minimum required concentration throughout the holding period, whereas the ≥50 μm candidates were more sensitive under extreme conditions but remained viable under typical holding durations and non-extreme temperatures. Collectively, the finalized candidates provide practical STO options that combine size compliance, routine maintainability, and control-holding validity for reproducible challenge-water preparation in land-based type-approval testing.
Interactions between dissolved organic matter of different molecular weights and hexabromocyclododecanes.
Hu J, Sun X, Wang P … +7 more , Liu X, Yang C, Hao Q, Zhu J, He P, Li T, Guo Y
Mar Environ Res · 2026 May · PMID 42235202 · Publisher ↗
Although dissolved organic matter (DOM) has been reported to interact with various persistent organic pollutants (POPs), the molecular-weight-dependent interactions between DOM and hexabromocyclododecanes (HBCDs) remain...
Although dissolved organic matter (DOM) has been reported to interact with various persistent organic pollutants (POPs), the molecular-weight-dependent interactions between DOM and hexabromocyclododecanes (HBCDs) remain poorly characterized. In particular, limited information is available on how DOM molecular weight regulates the binding affinity and fluorescence response of individual HBCD isomers, including α-, β-, and γ-HBCD. To elucidate the interactions between DOM of varying molecular weights and HBCDs, this study employed Fulvic Acid (FA), Humic Acid (HA), and Suwannee River Natural Organic Matter (SRNOM) as representative dissolved organic matter. Using ultrafiltration, ultraviolet-visible (UV-Vis) spectroscopy, three-dimensional excitation-emission matrix combined with parallel factor analysis (EEM-PARAFAC), and Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS) to characterize the relationships between HBCDs and DOM of different types and molecular weights. The results indicate that HBCDs addition affects DOM across all types and molecular weight ranges (30 KDa ∼0.45 μm, 10 ∼ 30 KDa, 1 ∼ 10 KDa, and <1 KDa). However, the interaction mechanism is complex and lacks uniform patterns, manifesting as fluorescence response (quenching or enhancement) varies with DOM type, molecular weight, and HBCDs concentration, exhibiting non-linear relationships. The apparent binding constants between the four molecular-weight fractions and HBCDs, as well as their individual isomers, decreased with increasing DOM concentration, with the highest binding constants observed at low DOM concentration. High-molecular-weight FA and HA exhibited stronger binding capacities, whereas SRNOM showed the highest binding constants at low concentrations for low-molecular-weight components. The binding constants of γ-HBCD with FA, HA, and SRNOM were significantly higher than those with other isomers, suggesting γ-HBCD have higher hydrophobicity and a stronger binding capacity with organic matter. This binding state may also directly influence its accumulation within organisms and potential bioavailability.
Long-term assessment of nutrient-induced eutrophication in Xiamen Bay: Implications for integrated watershed-coast management.
Ainin Q, Zhang M, Zhang X … +2 more , Yu D, Chen N
Mar Environ Res · 2026 May · PMID 42235201 · Publisher ↗
Coastal eutrophication, driven by increasing anthropogenic nutrient inputs, represents a major environmental threat to marine ecosystems worldwide. This study presents a comprehensive analysis of the spatiotemporal dynam...
Coastal eutrophication, driven by increasing anthropogenic nutrient inputs, represents a major environmental threat to marine ecosystems worldwide. This study presents a comprehensive analysis of the spatiotemporal dynamics of eutrophication in Xiamen Bay, a subtropical semi-enclosed coastal system in Southeast China, based on a decadal monitoring dataset (2008-2018) covering spring, summer, and autumn. We applied an adapted version of the HELCOM Eutrophication Assessment Tool (HEAT) to evaluate eutrophication status and identify its key drivers. The results revealed pronounced spatial heterogeneity: dissolved inorganic nitrogen (DIN) concentrations were highest in the Jiulong River Estuary, reflecting dominant riverine inputs, whereas elevated dissolved inorganic phosphorus (DIP) levels were found in Western Xiamen Bay and Tongan Bay, associated with localized sewage discharges. Seasonally, nutrient concentrations and eutrophication severity peaked in spring and autumn but were lower in summer, a pattern attributed to increased dilution and flushing during the wet season. Nutrient levels were identified as the primary determinant of eutrophication, with the Eutrophication Ratio (ER) closely tracking spatial and temporal nutrient distributions and reflected by chlorophyll-a responses. A persistently high molar DIN:DIP ratio (71.7-107) indicated that phosphorus (P) was the limiting nutrient throughout the study period. This HEAT-based assessment underscores the critical need for integrated watershed-coast management in Xiamen Bay. Effective mitigation requires a dual-nutrient (N and P) reduction strategy, implemented through advanced wastewater treatment, optimized agricultural practices, and strengthened cross-regional governance. The findings provide a scientific foundation for sustainable eutrophication management in rapidly developing subtropical coastal regions.
Depth-dependent temperature shifts and their impact on zooxanthellae dynamics and physiological stress in Anemonia sulcata.
Cohen-Sánchez A, Compa M, Quetglas-Llabrés MM … +5 more , Araujo O, Tejada S, Gil L, Pinya S, Sureda A
Mar Environ Res · 2026 May · PMID 42229194 · Publisher ↗
Warming seas represent a major threat: rising baseline temperatures and increasing frequency and intensity of marine heatwaves intensify physiological stress in marine organisms. In symbiotic cnidarians, thermal stress c...
Warming seas represent a major threat: rising baseline temperatures and increasing frequency and intensity of marine heatwaves intensify physiological stress in marine organisms. In symbiotic cnidarians, thermal stress can disrupt the host-symbiont balance by enhancing reactive oxygen species production, potentially leading to oxidative damage and bleaching. Depth can further modulate thermal exposure, as shallow habitats experience greater temperature variability and light intensity than deeper zones. The aim was to assess the effects of depth-dependent temperature shifts in Anemonia sulcata by sampling individuals at 0.2 and 1.5 m depth monthly from June to September 2024, with an additional sampling in November. Zooxanthellae density, chlorophyll a and c concentrations, antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase), and lipid peroxidation biomarker (malondialdehyde) were quantified. Discrete monthly temperatures did not differ significantly between depths; however, 24-h temperature records in July and August revealed diel peaks up to ∼31.1 °C in shallow habitats, approximately 2 °C higher than in deeper sites. Zooxanthellae density and chlorophyll a and c concentrations increased during the warmest months (August-September), particularly in shallow anemones. Catalase and glutathione peroxidase activities, together with malondialdehyde levels, were elevated in shallow individuals during July-September, whereas superoxide dismutase and glutathione reductase remained comparatively stable. These patterns indicate enhanced photosynthetic activity accompanied by increased oxidative stress in shallow habitats. In conclusion, although A. sulcata appears capable of short-term photoacclimation, the concurrent rise in lipid peroxidation suggests that antioxidant defences may become insufficient under repeated or prolonged warming, potentially preceding bleaching events.
Trophic ecology of two discarded elasmobranchs (Scyliorhinus canicula and Torpedo marmorata) in a NE Atlantic trawl fishery (Gulf of Cádiz).
Fernández-Oliveras C, Rodríguez-García C, Sarmiento-Carbajal J … +1 more , Cabrera-Castro R
Mar Environ Res · 2026 May · PMID 42229193 · Publisher ↗
In trawl fisheries, elasmobranchs are commonly caught as bycatch and discarded, including the lesser-spotted dogfish (Scyliorhinus canicula) and the marbled electric ray (Torpedo marmorata). This study examined their fee...
In trawl fisheries, elasmobranchs are commonly caught as bycatch and discarded, including the lesser-spotted dogfish (Scyliorhinus canicula) and the marbled electric ray (Torpedo marmorata). This study examined their feeding ecology in the Gulf of Cádiz and tested the hypothesis that S. canicula would display a broader and more diverse diet than T. marmorata, with diet composition in both species varying according to body size and environmental factors, and Levin's index indicating opportunistic feeding. A total of 303 individuals were analyzed between 2019 and 2022. The two species showed clear habitat segregation, with S. canicula more frequent at greater depths and T. marmorata in shallower waters, while both were more abundant during nighttime hauls. Diet analysis revealed higher prey diversity in S. canicula compared to T. marmorata, with crustaceans and teleosts as dominant prey in both species. T. marmorata showed a higher vacuity index, suggesting reduced feeding activity or more specialised foraging. In S. canicula, diet composition varied with body size, depth, and time of day, whereas no effects of sex or parasite presence were detected. Levin's index indicated a relatively narrow trophic breadth in both species. These results highlight species-specific differences in trophic ecology and the influence of biological and environmental factors on feeding strategies in discarded elasmobranchs. They underscore the ecological relevance of bycaught species in demersal food webs and support their inclusion in ecosystem-based fisheries management frameworks.
Assessment of the metabolic potential and transformation of aliphatic and polycyclic aromatic hydrocarbons by marine fungi from Mexican coastal and deep-sea environments.
Olguin J, Solís-Weiss V, Ponce-Vélez G … +4 more , Botello AV, Figueroa M, Walker AK, Velez P
Mar Environ Res · 2026 May · PMID 42229192 · Publisher ↗
The oil industry represents an environmental threat to marine ecosystems due to the risks of associated pollution. Crude oil is composed of various fractions, including saturated aliphatic and polycyclic aromatic hydroca...
The oil industry represents an environmental threat to marine ecosystems due to the risks of associated pollution. Crude oil is composed of various fractions, including saturated aliphatic and polycyclic aromatic hydrocarbons (PAHs), which are of great concern due to their toxic effects. Fungi are eurytopic heterotrophs that can biotransform complex compounds, making them a potential model for hydrocarbon bioremediation. In this study, we investigated the tolerance and biodegradation of aliphatic saturated hydrocarbons (n-hexadecane and 1-hexadecene) and PAHs (naphthalene, Nap, and benzo[a]pyrene, BaP) by seven microfungal isolates (two distinct genetic lineages of Corollospora maritima, Aspergillus sydowii, A. cejpii, and Aspergillus sp.) obtained in Mexico from marine coastal zones and deep-sea hydrothermal vents. Initial tolerance tests revealed statistically significant differences in growth between hydrocarbon-exposed fungi and controls; however, no significant differences were observed in the utilization bioassays. Measurable decreases in total organic carbon (TOC) and biochemical oxygen demand (BOD) were observed in the culture media after the use of hydrocarbons by fungi, suggesting biotransformation. Notably, gas chromatography coupled to mass spectrometry (GC-MS) confirmed a specific reduction of BaP in inoculated samples compared to controls, suggesting a metabolic potential of these marine fungi to use hydrocarbons for growing. These results highlight the potential use of marine fungi for PAH and aliphatic hydrocarbon remediation, providing a model for evaluating the biodegradative potential and tolerance of marine fungi towards recalcitrant pollutants in the oceans.
Feeding selectivity drives fine microplastic uptake and persistence in sand bubbler crab Scopimera globosa on an estuarine tidal flat.
Inoue T, Horinouchi M, Kon K
Mar Environ Res · 2026 May · PMID 42224812 · Publisher ↗
Microplastics (MPs) are widespread in coastal ecosystems. However, field evidence on the uptake of fine MPs by deposit feeders remains limited. We investigated the occurrence, size composition, and biological processing...
Microplastics (MPs) are widespread in coastal ecosystems. However, field evidence on the uptake of fine MPs by deposit feeders remains limited. We investigated the occurrence, size composition, and biological processing of MPs in the sand bubbler crab, Scopimera globosa, on a sandy tidal flat in the Tama River estuary (Tokyo Bay, Japan). Field surveys were conducted in the spring, summer, and autumn of 2024 to quantify MPs in surface sediments, crab-produced sand pellets, and crab tissues, and laboratory experiments were conducted to test ingestion size selectivity and elimination using fluorescent polystyrene beads. Sediment MP abundance did not significantly vary seasonally, whereas MP abundance increased in both sand pellets and crab tissues in the autumn. The mean size of MPs in sand pellets (25.1-28.1 μm) was larger than that in sediments (19.5-23.2 μm) and crab tissues (17.8-23.1 μm), consistent with particle sorting during feeding. In the laboratory, crabs preferentially ingested small MPs (10-20 μm), despite an equal supply of three size classes. Following exposure to fine MPs, internal MP counts decreased over time and were described by an exponential decay model, yielding an elimination half-life of 1.39 days and estimated times to 90% and 99% elimination of 4.61 and 9.21 days, respectively. These results indicate that MP burdens in S. globosa are governed by feeding activity and size-selective ingestion, and cannot be inferred from sediment MP loads alone.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe