Search Results (1,032)

Freshwater lakes worldwide are undergoing rapid degradation, raising concerns about the effectiveness of recent large-scale conservation interventions. China’s ‘10-year fishing ban’ represents one of the world’s most ambitious fishery moratoria, yet its ecosystem-level consequences remain poorly quantified. Using data from the two seasonal surveys conducted in Dongting Lake in 2019, we applied a mass-balanced Ecopath with Ecosim model to evaluate how fishing closure, and its combination with multi-species stock enhancement, affects trophic structure, energy flows, and system stability from 2021 to 2030. Simulations show that the closure-only scenario nearly doubles total ecosystem production, yet yields limited improvement in maturity indicators, reflecting a slow recovery of food web complexity. Across the tested closure-plus-enhancement scenarios, the highest projected system omnivory index occurred under scenario S5 (from 0.24 to 0.27), whereas the highest projected Shannon diversity index (from 0.59 to 0.64) and total transfer efficiency (from 10.80% to 11.12%) occurred under scenario S1, relative to the 2019 baseline. Based on the level-wise responses of the L9 treatments, a recommended combined scenario consisting of 1.04 t bighead carp, 4.30 t grass carp, and 1.14 t silver carp, with no additional black carp stocking, was constructed. Under this scenario, the model projected enhanced biomass recovery and a shorter restructuring period for key functional groups. Our study provides a reference for predicting ecosystem responses following the ‘10-year fishing ban’ and also provides data for ecosystem-based assessments for stock enhancement. Full article

Marine ranching is a crucial component of the “blue granary” strategy. Evaluating the long-term conservation effectiveness of artificial reef areas in marine ranches helps to assess the current conservation status, identify issues during the conservation process, and develop targeted solutions. Based on survey data from the national marine ranching in the western waters of Furong Island in 2019 and 2022, we used Ecopath with Ecosim version 6.7 to construct Ecopath models for the two periods. By comparing factors such as trophic structure, system attributes, and energy flows, we evaluated the potential ecological effects associated with sustained conservation and management activities. The results indicated that the trophic level structures of the ecosystem food web between 2019 and 2022 were similar. The trophic levels of most functional groups in 2022 were slightly higher than those in 2019, and the biomass increased significantly. The biodiversity slightly increased, with the Shannon index rising from 1.544 to 1.570, and the trophic levels of most functional groups increased. The overall ecosystem scale expanded by 29.37%, while total primary production/total respiration (TPP/TR), total primary production/total biomass (TPP/TB), and the ascendancy (A) value decreased, and Finn’s cycling index (FCI), mean path length (MPL), and transfer efficiency (TE) increased. Collectively, these changes suggest a tendency toward greater ecosystem maturity, although not all ecosystem indicators exhibited consistent responses. In the energy transfer process, the proportion of energy flowing into each trophic level improved. The detrital food chain dominated the system’s energy supply, though its proportion of total flow decreased from 61% to 57% over the years, while the energy contribution from primary producers increased, and the total transfer efficiency of both pathways improved. Analysis of mixed trophic impacts and keystone species revealed changes in keystone species. Overall, the observed changes from 2019 to 2022 were consistent with potential ecological improvements under sustained conservation and management. These findings will contribute to the further refinement of fisheries resource conservation methods and support decision-making for marine ecosystem restoration. Full article

Upon entering aquatic ecosystems, coal fly ash (CFA) particles and their leachates distribute across all environmental compartments, from surface water to benthic sediments, rendering them accessible to aquatic organisms spanning multiple trophic levels. Although CFA is widely classified as non-hazardous waste, a growing body of toxicological evidence demonstrates its capacity to induce significant adverse biological effects. This discrepancy between laboratory-demonstrated toxicity and its current non-hazardous regulatory status highlights a critical knowledge gap in risk assessment frameworks and testing philosophies. Herein, we provide a comprehensive review of CFA characterization techniques, leaching methodologies and their environmental relevance, and the aquatic ecotoxicity of both particulates and leachates to primary, secondary, and tertiary consumers. Based on the findings from the review, we propose four paradigm shifts to more accurately characterize CFA ecotoxicological risks: from standardized leaching protocols to application-specific and maximum leachability tests, from single-species assays to multi-trophic-level bioassays, from single-metal analysis to comprehensive, whole-matrix testing that integrates particulate and dissolved fractions, and from standardizing the reporting of CFA provenance, coal types, and combustion conditions to meaningful meta-analyses and cross-study comparisons. It is believed that these suggestions will substantially advance the realistic ecotoxicological assessment of CFA and bridge the gap between laboratory toxicity data and regulatory classification. Full article

Macrobenthic seaweeds are key species in temperate and boreal nearshore rocky ecosystems, and their interspecific interactions profoundly affect the species composition, spatial distribution and dynamic succession of the community. This paper systematically reviews the mechanisms of interspecific competition and facilitative effects among macrobenthic seaweeds. We also examine their environmental regulation and impacts on community phase transitions. Competition mainly centers on three major resources: light, space and nutrients. It manifests as an asymmetric hierarchical structure, in which canopy-forming species exert a disproportionate repressive effect on lower algal layers through light competition. Facilitative effects are realized through several mechanisms. These include canopy shading to mitigate heat stress and water loss, physical structure building to create complex habitats, and nutrient retention with chemical microenvironment regulation. Moreover, the relative strengths of facilitation and competition shift systematically across environmental stress gradients. Multi-trophic level regulation further shapes community diversity maintenance mechanisms through the suppression of dominant species by vegetative predators and the cascading effect of top predators on vegetative predators. In the context of global change, physiological asymmetries driven by oceanic heat waves are tilting the competitive balance in favor of opportunistic turf algae. These algae form a lock-in state through the triple positive feedbacks: physical barriers, biogeochemical deterioration, and chemosensory exclusion. This significantly decreases the resilience of algal field recovery. Tropical coral-macroalgae phase transition is highly consistent with the degradation of temperate algal fields in terms of driving logic. They follow the law of coupling resource competition imbalance, downward regulatory relaxation, and positive feedback lock-up. This paper suggests several priorities for future research. Studies should focus on the nonlinear response of multifactor interaction, the quantitative correlation between key functional traits and community resilience, and the establishment of a cross-ecosystem comparison framework. These efforts will provide theoretical support for predicting and adaptively managing offshore ecosystems under global change. Full article

Diapause serves as an adaptive dormancy strategy in freshwater, hypersaline, and marine crustaceans, allowing them to survive harsh conditions like temperature extremes, salinity fluctuations, hypoxia, and food scarcity. This review focuses on diapause across major crustacean taxa, with particular emphasis on branchiopods and copepods. However, detailed mechanistic evidence is more prevalent in well-studied species like Artemia, Daphnia, and calanoid copepods, leading to an uneven distribution of evidence across these taxa. Thus, the molecular and physiological mechanisms discussed in this review should not be assumed to be universally conserved across Crustacea, and taxon-specific differences and current knowledge gaps are highlighted where appropriate. The review consolidates the current understanding of crustacean diapause, focusing on environmental cues, gene-regulatory networks, hormonal and epigenetic control, metabolic suppression, and stress resilience. In the best-studied taxa, diapause has been associated with changes in the expression and/or activity of antioxidant defenses, small RNAs, energy-storage pathways, heat shock proteins, and FoxO-associated signaling components; however, the evidence for these mechanisms varies among taxa, and their conservation across Crustacea, remains uncertain. The functions of these responses include developmental arrest, energy conservation, cellular protection, and maintaining viability during dormancy. Their significance varies among different groups of organisms and remains incompletely understood in many cases. Diapause also contributes to the persistence of populations by forming dormant propagule banks, coordinating seasonal processes, linking trophic levels, and increasing resilience to environmental changes. The ecological effects of diapause depend on the life stage and habitat. Recent progress in transcriptomics, epigenomics, long-read sequencing, single-cell methodologies, and multi-omics integration present new opportunities for comparing regulatory responses across species. Molecular data primarily focuses on Artemia, Daphnia, and a limited number of copepod species, posing challenges in generalizing to less represented lineages. Previous syntheses have concentrated on individual taxa, physiological dormancy, or specific molecular mechanisms. This review aims to fill this gap by integrating environmental regulation, taxonomic and life-stage contexts, molecular and physiological mechanisms, and ecological and evolutionary implications systematically. This comparative approach distinguishes between shared regulatory features across species and lineage-specific characteristics, while considering variations in the strength of supporting evidence. Future research should prioritize functional validation, broader taxonomic inclusivity, comparative multi-species analyses, multifactorial experiments, and long-term ecological investigations to enhance understanding of crustacean diapause evolution and refine predictions amidst climate-induced environmental shifts. Full article

Elasmobranchs play a major role in shaping the structure and functioning of marine ecosystems through their position in food webs. The Lusitanian cownose ray Rhinoptera marginata, a benthopelagic species classified as Critically Endangered on the IUCN Red List, is frequently landed in fisheries off the Mauritanian coast, yet its trophic ecology remains poorly documented. We investigated the diet of R. marginata along the coast of Nouadhibou through stomach content analysis of 308 individuals sampled between March 2022 and August 2023; 135 stomachs (66 females and 69 males) contained identifiable prey and formed the basis of the analyses (disc width range 33–87 cm). Common dietary indices (frequency of occurrence, numerical and gravimetric percentages, Pinkas’ IRI, Hureau’s Q) were combined with multivariate approaches (PERMANOVA on Bray–Curtis dissimilarities, SIMPER, non-metric multidimensional scaling), measures of trophic niche breadth and specialization (Levins’ standardized index Bi, Shannon H′, Pielou’s J′, modified Costello plot), niche overlap (Pianka and Schoener indices), and ontogenetic modelling (generalized additive models). A total of 33 prey taxa were identified, dominated by Bivalvia (86.1% IRI), followed by Gastropoda (6.9%) and Crustacea (6.7%). The species exhibited a strongly specialized feeding strategy (Levins Bi = 0.06; Shannon H′ = 1.42) with high niche overlap between sexes (Pianka = 0.89). PERMANOVA detected significant compositional differences across seasons (pseudo-F = 6.98, p < 0.001) and size classes (pseudo-F = 4.98, p < 0.001) but not between sexes (pseudo-F = 1.87, p = 0.077). The proportion of bivalves significantly decreased with body size (R² = 0.176, p < 0.001), revealing a clear ontogenetic shift towards more diversified prey in larger individuals. The estimated trophic level (3.13) confirms a mesocarnivore benthic position. These results provide the first comprehensive description of the diet of R. marginata in West Africa and highlight its role as a specialized durophagous predator of bivalve molluscs, omnipresent along the northern Mauritanian coastal ecosystems. By identifying the principal prey, our findings provide a basis for identifying potentially important foraging habitats for this Critically Endangered species and informing future conservation and management strategies. Full article

River-connected lakes are characterized by complex hydrological regimes, where hydrodynamic conditions serve as key physical drivers of aquatic ecosystem evolution and eutrophication. However, traditional water-balance methods struggle to accurately quantify water exchange under strong seasonal water-level fluctuations and the backwater effect of the Yangtze River, resulting in significant gaps in understanding lake hydrodynamic features and their seasonal eutrophication response patterns. Taking Dongting Lake as an example, this study employed a two-dimensional hydrodynamic model coupled with the advection–dispersion equation of a conservative tracer to simulate the spatiotemporal patterns of flow velocity and water turnover time during the dry season, rising-water season, wet season, and receding-water season using observed hydrological data from 2017 to 2025. Field sampling data and structural equation modeling were further used to identify the pathways through which hydrodynamic conditions affect lake trophic status. Flow velocity and water turnover time exhibited significant spatiotemporal heterogeneity: water turnover time was generally within 10 d in main flood channels but exceeded 60 d in stagnant floodplain areas and local topographic depressions. Seasonally, it was shortest in the wet season due to enhanced hydrological connectivity, yet longest in the dry season because of weakened hydraulic connection. The effects of hydrodynamics on trophic status were strongly season-dependent: during the rising-water season, hydrodynamics inhibited nutrient accumulation through dilution and flushing; during the wet season, strong runoff promoted external nutrient input; and during the dry season, hydrodynamics mainly affected trophic status by modifying physical habitat conditions for algal growth. These findings reveal the hydrological and hydrodynamic mechanisms regulating eutrophication in typical river-connected lakes, providing direct scientific support for hydrological regulation optimization, zonal eutrophication prevention and control, and water environmental carrying capacity assessment in Dongting Lake and similar systems, enabling lake managers to formulate differentiated pollution control strategies based on the hydrodynamic–trophic status response relationships across different hydrological seasons. Full article

Eutrophication in shallow plain lakes is highly dynamic and often characterized by short-term trophic fluctuations that are difficult to resolve using annual or single-sensor satellite observations. The Eastern Plain Lake Zone (EPL) of China contains numerous shallow lakes and reservoirs embedded in densely populated and intensively cultivated lowland catchments, making it a representative region for high-frequency eutrophication monitoring. Here, we developed a monthly Trophic State Index (TSI) monitoring framework for lakes and reservoirs in the EPL using Harmonized Landsat–Sentinel (HLS) observations. The XGBoost model using combined spectral features achieved the best validation performance (R² = 0.90, RMSE = 5.23), and provided the highest trophic-state classification accuracy, with an overall accuracy of 0.73 and a Kappa coefficient of 0.66. Lakes showed substantially higher trophic levels than reservoirs, with mean TSI values of 57.32 ± 6.89 and 45.00 ± 9.22, respectively. Temporally, significantly decreasing and increasing TSI trends accounted for about 15% and 5%, respectively. Natural lake TSI reflects integrated climatic, anthropogenic, and hydro-morphological influences, whereas reservoir TSI variability may be more closely associated with hydrological regulation and morphometric conditions. Our results show that HLS observations provide a robust basis for monthly eutrophication monitoring in optically complex shallow lake regions. The EPL-focused framework highlights the value of virtual satellite constellations for detecting short-term trophic deterioration and supporting region-specific lake and reservoir management. Full article

With climate change, marine heatwaves become more frequent and may favour the emergence of cyanobacterial blooms. Because cyanobacteria lack long-chain polyunsaturated fatty acids, they provide poor dietary quality for consumers, potentially altering the fatty acid composition of primary consumers and propagating nutritional stress through food webs. We examined how a simulated heatwave (12 °C to 18 °C) and an associated cyanobacterial bloom-like dominance may affect trophic transfer from phytoplankton to the herbivorous rotifer Brachionus plicatilis and further to its predator, the mysid Neomysis integer. Rotifers were fed either high-quality algae or a low-quality cyanobacteria-dominated diet mixture. Rotifers were then rinsed to remove external residual phytoplankton and subsequently offered as prey to mysids. We analyzed the fatty acid profiles of both rotifers and mysids and monitored mysid survival. High temperature and the presence of cyanobacteria at the base of the food web reduced mysid survival. Both factors also influenced the fatty acid composition of rotifers and mysids. For mysids at the third trophic level, warming modulated how strongly diet quality affected their fatty acid profile. These results suggest that concurrent heatwaves and cyanobacterial blooms may intensify cyanobacteria’s negative impacts on food webs by altering the transfer of key fatty acids across trophic levels. Full article

This study examines how students aged 10–20 conceptualize Education for Sustainable Development (ESD), focusing on their ability to think multiperspectively and justify decisions multidimensionally. In a classroom-based teaching experiment, 131 high school students from Lower Saxony completed a drawing task visualizing sustainable village transformations, followed by interviews with twelve participants. Their negotiation processes, verbal responses, and drawings were analyzed using qualitative content analysis. The visualization of village transformations functions as a biology-didactic ESD activity, where students apply decision-making and problem-solving strategies to address biological system levels (e.g., individuals, populations, ecosystems) and their interconnections (trophic levels, food webs, biodiversity). Results indicate age-related differences: students in grades 5–7 primarily emphasized social and ecological aspects, designing idealized living spaces for themselves. Upper-secondary students (grades 11–13) incorporated societal, political, and economic considerations, prioritizing economic development. However, no consistent relationship between multiperspectivity and multidimensional reasoning was identified. Based on these findings and related research, the study advocates integrating systems thinking with a comprehension-oriented approach, combining the Conceptual Metaphor Theory (CMT) and the Model of Educational Reconstruction (MER). This aims to address the complexity of ESD more effectively, avoiding oversimplified, monocausal narratives that undermine the multidimensional nature of sustainable development. Full article

Microplastic pollution severely threatens aquatic ecosystems, yet the trophic microecological risks of petroleum-based polyvinyl chloride (PVC) and biodegradable polyhydroxyalkanoate (PHA) microplastics remain insufficiently compared. This study established a two-trophic food chain model with Daphnia magna and zebrafish to explore the toxic effects and microbial disturbances of environmentally relevant 0.1 mg/L PVC and PHA. A 21-day chronic exposure induced no physiological damage to the survival, growth, reproduction, and locomotion of both organisms, suggesting conventional phenotypic indicators fail to identify early microplastic stress. However, trophic microplastic exposure triggered prominent zebrafish gut dysbiosis with distinct pathogen enrichment patterns. PHA trophic exposure enriched plant pathogenic genera (Acidovorax, Clavibacter, Rhizobium), whereas PVC trophic exposure accumulated zoonotic and clinical pathogens (Acinetobacter, Neisseria, Mycobacterium, Aeromonas). This work verifies that PHA is not entirely eco-safe, and PVC poses greater ecotoxicological risks via trophic pathogen transmission, providing genus-level evidence for differentiated microplastics risk assessment. Full article

Microplastics have emerged as a persistent and prevalent threat to human health and the marine environment due to their widespread use and poor management, including low recycling rates, inadequate waste management, improper disposal, and inadequate control of plastic leakage into the environment. Plastic pollution is transported to the marine ecosystem through both ocean-based and land-based pathways and can be fragmented into microplastics (<5 mm) and nanoplastics (<1 µm). The study explains the sources, distribution, mechanisms of degradation, and transport pathways to the marine environment. Land-based activities are recognized as the dominant source, causing approximately 70–80% of marine plastic pollution. Domestic greywater is highlighted as a significant and common source of microplastics due to the release of microbeads and synthetic fibers from different sources, such as laundry, washbasins, and personal care products (PCPs). Similarly, greywater release from maritime vessels and cruise ships significantly contributes to marine microplastic pollution. The study discusses the biotic and abiotic degradation mechanisms. The health and environmental effects of microplastics are measured across different trophic levels. Ingestion and bioaccumulation of microplastics can cause physiological and reproductive disturbances. Human exposure through seafood consumption and inhalation may result in skin infections, cardiovascular complications, gastrointestinal disorders, and respiratory problems. The mitigation and control measures include improvements in wastewater treatment, public awareness, policy regulations, and biodegradable alternatives to support sustainable protection of the marine environment. Full article

Plantations dominated by different tree species can differ in soil nutrient cycling and microbial community assembly, but corresponding bacterial and fungal patterns have not been characterized for mature plantation stands and a natural secondary forest in the Longmen Mountains of southwestern China. This study compared a natural secondary forest (SF) with four plantations, Magnolia officinalis (MO), Juglans regia (JR), Larix gmelinii (LG), and Cryptomeria japonica (CJ), in the Longmen Mountains of southwestern China, and investigated soil physicochemical properties, enzyme activities, bacterial and fungal community composition, co-occurrence networks, and predicted functional profiles in the 0–20 and 20–40 cm soil layers. The results showed that stand type was associated with total nitrogen (TN; p = 0.012), dissolved organic carbon (DOC; p < 0.001), dissolved organic nitrogen (DON; p < 0.001), and urease activity (p = 0.018), whereas pH differed between soil layers (p = 0.024) but not among stand types (p = 0.270). Relative to SF topsoil, DOC was 29.2% higher in JR and 36.1% higher in LG, while DON was 42.0% higher in JR and 51.4% higher in LG. TN and DON also showed stand type × soil layer interactions. None of the bacterial or fungal Chao1, Shannon, or Simpson indices showed significant stand type, soil layer, or interaction effects. In contrast, PERMANOVA indicated that bacterial and fungal community composition differed among the sampled stand types (p < 0.05), and fungal community composition also differed between the two soil layers (p < 0.05), whereas bacterial community composition did not. Paired partial dbRDA indicated that the integrated soil environmental gradients represented by the first three PCA axes were associated with bacterial community composition (R² = 0.083, p = 0.012), whereas the corresponding association was not significant for fungi (R² = 0.080, p = 0.371). Within the retained co-occurrence network analysis, MO had the most complex bacterial network, and JR had the most complex fungal network. PICRUSt2-predicted profiles were dominated by metabolism (38.6%–39.3%), but no bacterial KEGG Level 1 category or FUNGuild trophic-mode category showed a stand type, soil layer, or interaction effect after correction for multiple testing. These findings indicate that differences among the sampled stands were expressed more clearly in active carbon and nitrogen pools and microbial community composition than in alpha diversity or broad predicted functional profiles. Full article

Understanding how animals operationally identify and exploit resource patches is central to foraging ecology. The “patch”—a discrete area of resource concentration—is the fundamental unit of individual foraging behavior; however, standardized operational definitions of the criteria for patch identification across taxa, habitats, and biomes are still scarce. Following PRISMA 2020 guidelines, we reviewed 87 empirical studies encompassing 133 species, classifying patch identification methods across eight macro-categories of the European Nature Information System (EUNIS)—a structurally detailed habitat classification that, despite its European origin, we apply here as a general structural template for habitat architecture rather than as a claim of biogeographic universality, given that our dataset also spans non-European taxa and biomes. Patches are operationally identified through two approaches: observational delineation of natural resource structures (e.g., fruiting trees, prey aggregations, vegetation clusters) and experimental manipulation via artificial depletable units. We demonstrate that habitat structural complexity and species trophic preferences jointly govern the operational method by which patches are identified: habitat architecture determines which operational approach is used for patch delineation—observational or experimental—while a four-category Feeding Guild classification (Granivore, Herbivore, Omnivore, Carnivore) reveals that resource discretizability—the capacity to standardize prey into countable, depletable units—operates as the primary species-level predictor of patch identification method selection, an association that remains robust after formally controlling for phylogenetic non-independence and body mass in a mixed-effects model. The resulting framework provides, for the first time, a standardized operational guide for calibrating patch identification methods to habitat type and species trophic preferences and searching behavior across taxa and biomes. Full article

This study evaluated seasonal variations in mesozooplankton carbon biomass in Laguna de Terminos, a tropical coastal lagoon of the Southern Gulf of Mexico and a designated Ramsar site. We compared data from two contrasting 2022 sampling periods, the dry season (April) and the rainy season (October), coinciding with a strong La Niña event. Through systematic expeditions, we collected hydrographic and biological data to estimate zooplankton carbon biomass and assess its relationship with prevailing climatic conditions. Our results revealed distinct seasonal shifts. While surface water temperatures were higher in October (30 °C) than in April (28 °C), salinity and total dissolved solids exhibited the inverse trend. Chlorophyll-a peaked in April (>5 mg m⁻³) near river discharges and the lagoon’s connection to the Gulf of Mexico. Consistent with this, zooplankton carbon biomass was higher in April (up to 77.2 mg C m⁻³) than in October (up to 48.4 mg C m⁻³), with maximum concentrations observed in the eastern section of the lagoon. Given the scarcity of published reports for this system, these findings establish a critical baseline for future environmental monitoring. Furthermore, this data is essential for evaluating the lagoon’s primary and secondary productivity potential and for estimating the carbon pool held within lower-trophic-level organisms that support higher-level consumer groups. Full article