Search Results (907)

Iberian reservoirs are highly vulnerable to droughts, warming temperatures, and agricultural runoff, which accelerate eutrophication. Monitoring these dynamics is crucial for sustainable management. This study investigated long-term trends in chlorophyll-a (Chl-a) and water transparency Secchi depth and developed empirical models for the Alto Rabagão (Rb) and Aguieira (Ag) reservoirs in Portugal. We used Sentinel-2 Level-2A reflectance data coupled with 153 in situ observations (2014–2024) for model calibration (n = 95) and validation (n = 58). Temporal trends were assessed using linear regression and Mann–Kendall analyses. Empirical models based on spectral indices (TBDO1, TBDO, MCI, NDWI) were evaluated using walk-forward time-series cross-validation. Results revealed a significant Chl-a increase (0.38 µg L⁻¹ year⁻¹; p = 0.016) and a simultaneous decline in transparency (p < 0.001) in Rb, indicating progressive eutrophication. In contrast, no significant trends were detected in Ag. Reservoir-specific models achieved moderate-to-high predictive performance, particularly for Chl-a (R² up to 0.75; cross-validated R² = 0.67–0.68, RMSE = 1.1 µg L⁻¹, MAE = 0.82 µg L⁻¹). Models using combined datasets showed lower accuracy, highlighting the importance of site-specific calibration. Wilcoxon signed-rank tests confirmed the absence of systematic bias between observed and predicted values. Ultimately, Sentinel-2 imagery combined with time-series cross-validation provides a reliable and cost-effective framework for the long-term monitoring of inland water quality. Full article

Landslides pose a significant natural hazard requiring cost-effective, sustainable mitigation strategies. Nature-based solutions utilizing vetiver (Chrysopogon zizanioides) demonstrate considerable potential due to its deep, dense root system, which enhances soil reinforcement. This study examines the effects of growth medium composition and NPK fertilization on the root mechanical properties, biomass accumulation, and vegetative growth of vetiver under controlled greenhouse conditions. The planting medium comprised landslide-affected soil mixed with compost in varying proportions, combined with different NPK fertilizer levels. Root tensile strength was measured to assess mechanical performance, while biomass and vegetative parameters were evaluated to determine growth responses. Results indicate that both growth medium composition and fertilization significantly influence biomass production, root diameter, and tensile strength. The highest biomass (178.33 g) was recorded under T80P20N7.5, while the greatest root diameter (1.47 mm) and tensile strength (21.9 MPa) were observed under T100P0N0. These outcomes suggest a trade-off between biomass production and mechanical reinforcement. Overall, optimizing soil amendments and nutrient inputs enhances vetiver’s bio-reinforcement capacity, supporting its application in sustainable slope stabilization and landslide mitigation. Full article

Bacterial density, cell morphology, and carbon stock (C stock) were quantified in seven Brazilian reservoirs (Serra da Mesa, Manso, Itumbiara, Corumbá, Furnas, Mascarenhas de Moraes, and Luis Carlos Barreto) to evaluate spatial and seasonal patterns in these tropical freshwater systems. Subsurface water samples were collected before, during, and after the rainy season. Bacterial density, cell volume, elongation, and biomass were determined using epifluorescence microscopy, and bacterial C stock was estimated from biomass integrated over the 0.5 m sampling depth. C stock varied among reservoirs and sampling periods, with the highest values consistently observed in the largest reservoir (Serra da Mesa, 1.9·10⁻⁵ g C). Although bacterial densities showed limited temporal variation, biomass peaked before the rainy season. Density and biomass were negatively correlated with water transparency and positively correlated with turbidity, suggesting that particle-associated organic and inorganic matter influences bacterial biomass accumulation. These findings highlight how environmental conditions shape bacterial biomass and carbon storage in tropical reservoirs, contributing to a broader understanding of microbial carbon pools in these ecosystems. Full article

Charal (Chirostoma spp.) is a small pelagic fish of high nutritional and economic importance in central Mexico. However, its high moisture content and rapid post-harvest deterioration result in substantial losses in artisanal fisheries. Solar drying represents a sustainable preservation alternative, particularly in regions with limited access to refrigeration. This study investigates the drying kinetics of whole charal under field-realistic mild-to-moderate solar drying scenarios, including forced convection, natural convection, and open-air exposure. Experimental drying curves were modeled using classical thin-layer formulations, and neural network models were evaluated as complementary one-step-ahead predictors of experimental moisture ratio. Among the evaluated thin-layer models, the Modified Page formulation consistently provided the most reliable empirical description of the drying curves, with coefficients of determination greater than 0.97. An ablation-style comparison of ANN, CNN, LSTM, and CNN-LSTM architectures showed that the CNN model achieved the highest global predictive accuracy in the present dataset, with R² = 0.987 and MSE = 4.3 × 10⁻⁴. Because the dataset contained a limited number of independent drying curves, the deep-learning results are interpreted as exploratory and complementary to thin-layer modeling rather than as a replacement for classical empirical models. The proposed framework may support future drying-endpoint estimation and decision-support tools for artisanal fish processing, provided that additional validation is performed with standardized sample masses, environmental covariates, and product-quality indicators. Full article

Kobuviruses infect a wide range of hosts and exhibit high genetic diversity, highlighting the need for further studies to better understand their evolution and impact on animal health. In the present study, bovine kobuvirus (BKoV) was detected in 40 of 154 fecal samples from calves using the primers targeting the 3D gene region, corresponding to an overall positivity rate of 25.97%. All positive samples were obtained from diarrheic calves younger 30 days of age, (40/133; 30.08%), consistent with previous studies. To enable more reliable genotyping, the complete VP1 gene sequences of seven BKoV strains were obtained, and the phylogenetic analyses showed that all VP1 sequences of this study clustered within Aichivirus B1. Additionally, immunoinformatics analysis of the VP1 protein identified conserved linear and discontinuous B-cell epitopes that may represent potential targets for cross-reactive diagnostic assays or future vaccine studies. The complete coding sequence of one strain, K056/2008/TUR, was also generated, and molecular analysis of this strain provided further evidence of ongoing viral evolution and genetic diversity in Türkiye. Overall, these findings provide new insights into the prevalence, genetic diversity, and predicted immunogenic features of BKoVs in calves in Türkiye, supporting further studies on its pathogenesis, diagnostics, and antigenic properties. Full article

The classification position of substrates forming on the beds of aquaculture ponds remains a poorly resolved issue at the intersection of pedology, limnology, and aquaculture science. We examine how major international and national soil classification systems—the USDA Soil Taxonomy, the World Reference Base for Soil Resources (WRB), the German Bodenkundliche Kartieranleitung, the Australian Soil Classification (ASC), the Russian Soil Classification, and the classification systems of Brazil and China—approach the systematics of subaqueous soils and their aquaculture analogues. A systematic literature search was conducted across the Web of Science, Scopus, and Google Scholar databases covering the period from 1953 to 2025. Our analysis reveals that Soil Taxonomy provides the most developed taxonomic framework through specialized suborders (Wassents and Wassists), while the WRB offers the greatest flexibility via its qualifier system (subaquatic, limnic, and gleyic). The German classification uniquely assigns subaqueous soils to the highest taxonomic level (division) with a substantive typology that is directly applicable to pond substrates. The Australian classification contributes a three-part sulfidic material typology of practical significance for pond management. The Russian and Brazilian systems currently lack formal taxa for subaqueous soils, although recent proposals (e.g., Aquazems) may address this gap. The Chinese paddy soil model offers a conceptual bridge between subaqueous pedology and aquaculture. No existing system adequately addresses the specific anthropogenic impacts of aquaculture management on pond soil formation. Permanently inundated little-disturbed ponds fall within the subaqueous soil concept, whereas intensively managed, frequently drained or dredged ponds are better treated as anthropogenic soils with a subaqueous phase. We recommend the WRB (4th edition, 2022) as the most suitable framework for current classification of aquaculture pond soils while acknowledging that a multi-system approach may ultimately prove most effective. These findings carry particular relevance for countries of the former Soviet Union (CIS), where extensive pond aquaculture is practiced but pond substrates remain outside formal pedological classification. Full article

Comprehensive biological and ecological data are essential for the appropriate stock management of Solenocera alticarinata Kubo, 1949. The lack of ecological knowledge on S. alticarinata, a species of potential economic value in the East China Sea, limits the development and implementation of appropriate fishery management measures such as minimum landing size and seasonal closure. Accordingly, we employed research vessels to characterize the seasonal spatial distribution patterns of S. alticarinata within the study area (26.5–35° N, 120–127° E) in 2018–2019. Our findings indicate that S. alticarinata can survive at a depth of 50–120 m and sea bottom salinity of 33–35. The highest biomass-based CPUE and greatest abundance of S. alticarinata were found during the summer and autumn, respectively. The seasonal ranking of the total catch per unit effort in number was as follows: autumn (1438.7 ind·h⁻¹) > summer and winter (1012.1–1078.2 ind·h⁻¹) > spring (287 ind·h⁻¹). In terms of mean average individual size, the order was summer > spring > autumn and winter. Overall, our findings provide a basis for developing management policies, and offer insights for designing fishery management and conservation strategies. Full article

Radioisotopic techniques provide powerful tools for reconstructing the history of lake sediments, offering critical insights into past environmental changes and human impacts. These techniques have contributed significantly to our understanding of past environmental change and have implications for current environmental management practices. This review comprehensively examines various radiometric dating techniques used for lake sediments, with a focus on natural, cosmogenic, and artificial radionuclides, including ²¹⁰Pb, ¹³⁷Cs, ²⁴¹Am, ⁷Be, ³H, and ¹⁴C. The review highlights the widespread use of radionuclides in establishing sediment chronologies across different time scales, from short-term processes (days to decades) to long-term environmental reconstructions spanning thousands of years. Moreover, applications in limnological research are explored, including sedimentation rate estimation, reconstruction of pollution history of trace elements, nutrients, microplastics, and organic compounds, and assessment of anthropogenic impacts and catchment changes. The integration of radioisotopic methods with multiproxy paleolimnological approaches is emphasized as a powerful framework for reconstructing past environmental and ecological conditions. Despite their effectiveness, radioisotopic methods are exposed to several sources of uncertainty, including dispersion in atmospheric isotope flux, post-depositional processes, reservoir effects, and model assumptions. These challenges highlight the importance of careful methodological selection, site-specific evaluation, and rigorous uncertainty assessment in radioisotopic studies of lake sediments. Future research should emphasize refining sediment age-model calibration using region-specific sedimentation parameters and standardized validation procedures, and integrating radiometric techniques with geochemical, biological, and paleolimnological proxies to improve the reconstruction of environmental change in lacustrine systems. Such developments would enhance the interpretation of historical pollution records, sediment accumulation patterns, eutrophication history, and ecological variability, thereby providing scientifically robust information to support evidence-based lake management, restoration programs, and long-term conservation strategies. Full article

The Tietê River, heavily polluted by the largest Brazilian city (São Paulo), has significant ecological and socioeconomic importance. The effects of water-quality degradation on zooplankton diversity (taxonomic and functional) and limnological variables were evaluated through a comparison of the Tietê River’s main channel, one of its marginal lagoons and a low-impacted tributary. Samplings covered both a rainy and a dry season. Environmental conditions are distinctive, with the main river and lagoon classified as hypereutrophic and the tributary as oligo-mesotrophic. The zooplankton, an essential community for aquatic ecosystem functioning, also exhibited remarkable spatial variation. Richness varied between six (lagoon/dry) and 43 (tributary/rainy). There was a much higher abundance in the lagoon (mean = 6.5 × 10⁵), followed by the Tietê River (mean = 4.0 × 10⁴) and tributary (mean = 2.5 × 10³), and a higher taxonomic diversity (Shannon mean = 2.98) and functional richness (mean = 0.66) in the tributary, contrasting with the intermediate values in the Tietê River (means of 1.7 and 0.31, respectively) and lower in the lagoon (1.49 and 0.01). Zooplankton from the Tietê River and the lagoon positively correlated with pH, total solids, chlorophyll and phosphorus. Negative pollution’s effects on the zooplankton community were intensified by the lagoon’s lentic hydrodynamics. The low-impacted tributary seems to act as a refuge for the regional zooplankton biodiversity, taxonomically and functionally, which is restricted to highly tolerant species in the main river. Full article

Mineral waters represent unique limnological ecosystems with stable physicochemical conditions and specialised microbial communities adapted to extreme environments. Bulgarian mineral waters remain comparatively underexplored despite their considerable ecological and biotechnological significance. These studies present a systematic narrative review of microbial diversity, ecological functions, and biotechnological potential of microbial communities from Bulgarian mineral springs. A total of 233 scientific sources published between 1990 and 2026 were analysed, of which 33 focused on Bulgarian sites. Data were retrieved from major scientific databases, regional reports and grey literature. Due to strong methodological heterogeneity, a qualitative synthesis was conducted, supported by bibliometric summaries of research focus and environmental context. The available evidence demonstrates that microbial communities in Bulgarian mineral waters include diverse bacteria, archaea, cyanobacteria, and microalgae that adapt to broad thermal and geochemical gradients. These microorganisms actively participate in element cycles, form complex biofilms, and show numerous physiological adaptations to oligotrophic and extreme temperature conditions. Bulgarian systems broadly reflect global microbial patterns but exhibit additional variability linked to contrasting hydrogeological settings. Many taxa produce thermostable enzymes, antimicrobial compounds, and exopolysaccharides with significant biotechnological potential. The review identifies significant research gaps and emphasises the importance of integrated multi-omics approaches for future exploration of Bulgarian mineral water ecosystems. Full article

Vegetation change in cryosphere-affected mountain basins reflects interacting climate and human pressures but their relative influence remains uncertain in the Upper Indus Basin. The novelty of this study is the integration of satellite vegetation, climate variables, human pressure indicators, residual attribution and diagnostic validation in a data-scarce high-mountain basin. We evaluated growing-season Normalized Difference Vegetation Index dynamics and associated drivers from 2001 to 2023 using trend analysis, correlation, Random Forest diagnostics, Sentinel 2 validation, and residual trend analysis. The results showed widespread greening across 96.59% of the basin, with stronger improvement in the lower and central areas. Significant greening covered 69.94% of the basin, while only 1.55% showed significant browning. Precipitation and temperature were predominantly positive drivers of vegetation change, whereas potential evapotranspiration and solar radiation were mostly negative. Soil moisture played a strong regulatory role along elevation gradients. Residual trend analysis provided approximate and method-dependent estimates of the possible anthropogenic influence on vegetation change at 73.09% and climatic drivers at 26.91% rather than direct causal decomposition. These values are approximate and method-dependent estimates, not direct causal decomposition. The findings highlight human-related greening in lower valleys and climate-controlled vegetation responses in high-mountain areas. Full article

This research investigates the effects of incorporating cyanobacterium Oscillatoria limnetica (OL) powder into aquafeeds on the growth rates, activity of digestive enzymes, antioxidant status, and innate immune responses of white-leg shrimp, Litopenaeus vannamei. The shrimps’ resistance against possible infection with Vibrio harveyi was also examined. For 12 weeks, shrimps (1.26 ± 0.088 g) were nourished on experimental diets with 0.0, 0.75, 1.5, 2.25, and 3.0 g OL/kg feed, represented as OL0, OL0.75, OL1.5, OL2.25, and OL3.0, respectively. At the end of the feeding trial, shrimps were challenged by V. harveyi, and their mortality was further observed for further ten days. The shrimps fed on OL-enriched diets, particularly OL3.0, showed significantly greater growth, digestive enzyme activities, and innate immunity performance than those fed on the control diet (OL0). Compared to the control group, enzymatic antioxidant parameters (CAT and SOD) were significantly (p < 0.05) higher; meanwhile, MDA levels showed marked declines in shrimps fed on OL-containing diets (particularly OL3.0). The relative mRNA expression of antioxidant-related genes (cMn-SOD, CAT, and GPx) and immune-related genes (HMC, Alpha2M, ProPO, and Pen3a) was upregulated in the OL-fed animals compared to the control group. The intestinal morphometry was markedly enhanced in the animals fed on OL-enriched diets, especially with respect to the OL3.0 diet. After the bacterial challenge assay against V. harveyi for ten days, shrimps fed on the control diet had 83.3% mortality; meanwhile, the mortality rate was lower in shrimp groups fed on OL diets, particularly OL3.0 (46.7%). This study demonstrates that L. vannamei benefits from dietary inclusion of O. limnetica (3.0 g/kg feed) through accelerating its growth due to better digestion of diets. Additionally, the OL meal acts as a functional ingredient that fortifies the shrimp against possible V. harveyi infection by enhancing their biological defense system. Full article

The goal of this study was to replace the costly fishmeal (FM) with Tenebrio molitor larvae meal (TMLM) in diets for Nile tilapia (Oreochromis niloticus) juveniles. Six isonitrogenous diets were created in order to examine the viability of substituting FM protein with stepwise inclusion levels of TMLM protein, i.e., 0%, 15%, 30%, 45%, 60%, and 75% represented by TMLM0, TMLM15, TMLM30, TMLM45, TMLM60, and TMLM75, respectively. For 90 days, Nile tilapia juvenile (8.8–10.5 g) were fed on TMLM diets three times a day until apparent satiation. Nile tilapia fed on TMLM levels were found to significantly (p < 0.05) boosted their growth and feed efficiency indices by up to 45%, after which their performance declined. In comparison to other treatments, larger villi length/width and increased digestive enzymes activity were observed at this level (TMLM45). At TMLM45, there were no signs of inflammation in the liver tissues but feeding the fish on TMLM60 and TMLM75 showed more vacuolated hepatocytes and fewer hepatic sinusoids. Total protein, albumin, and globulin contents showed significant (p < 0.05) increases in response to TMLM levels in fish feeds; meanwhile no significant (p > 0.05) changes in blood glucose were observed compared to the control one (TMLM0). The values of alanine and aspartate aminotransferase, total cholesterol, and triglycerides decreased significantly (p < 0.05) as TMLM levels increased in fish feeds. In addition, significant (p < 0.05) increases in antioxidant and immunological variables were observed in fish fed with TMLM diets, in particular TMLM45. The current study concluded that the substitution of FM protein by 45% TMLM protein in diets administered to Nile tilapia juveniles significantly improved (p < 0.05) their growth, antioxidant, and immune response compared to the control diet (FM-based diet). Full article

With the advancement of urbanization, the functions of cities continue to expand and deepen, among which the tourism function plays an increasingly important role in urban and regional economic development. To resolve the challenges in data acquisition for urban function classification and assessment, this study introduces POI data and machine learning methods to construct an employment sector distribution model. This enables the estimation of tourism-related employment data in Pacific Island countries. The tourism function of these cities is quantitatively evaluated based on two dimensions: functional scale and functional intensity. The results show that: (1) The constructed employment sector distribution model demonstrates strong predictive performance. The error rate for the total employed population in each island country is below 10%. The Bootstrap robustness test confirms that predicted values for all countries fall within the 95% confidence interval. The number of tourism employees shows a significant positive correlation with inbound tourist numbers and the count of tourism-related POIs at the 0.01 level. Empirical validation shows tourism-related sector error rates of 4.44% for Ningbo and 9.02% for Wuxi, both of which are under 10%. (2) Tourism in thirteen countries, including Samoa and Tonga, constitutes a fundamental function of the national economy, whereas in Papua New Guinea, tourism is a non-fundamental function, reflecting a lower degree of economic reliance on the tourism sector. (3) A provisional typology of tourism functions is proposed, identifying Fiji and The Cook Islands as robustly specialized, while Papua New Guinea remains characterized by stable low-specialization. The remaining 11 countries occupy transitional positions where classification is sensitive to prediction uncertainty. Subject to this caveat, the PICs are provisionally categorized into three groups: medium-to-large specialized (Fiji, Cook Islands, Vanuatu, and Samoa), small specialized (Tuvalu, Palau, Solomon Islands, and Tonga), and low-specialization (Papua New Guinea, Kiribati, Federated States of Micronesia, Nauru, Niue, and Marshall Islands). The classification results can guide these island nations in enhancing their tourism functions, fostering sound regional development, and enabling more effective participation in global governance. Full article

The preservation of hydrobiological diversity is essential to ensuring the stability of the food chain and the sustainable development of high-Andean basins, which face increasing vulnerability to anthropogenic factors such as the construction of dams and reservoirs. In this study, multiple regression models, both linear and nonlinear, were developed to predict the Shannon–Wiener (H′) and Pielou (J′) indices of periphyton and macrobenthos using 21 water quality parameters and concentrations of nine metals in sediments. Samples of macrobenthos and periphyton were collected at seven monitoring stations during the dry and wet seasons between 2014 and 2025. For the analysis, linear regression models were compared with nonlinear machine learning models, specifically Gradient Boosting and Random Forest. Principal component analysis (PCA) revealed that variability of the basin’s ecosystem is dominated by geogenic factors (conductivity, boron, chlorides, and arsenic) and thermal influence. The Gradient Boosting model demonstrated superior predictive capacity (R² = 0.768 for macrobenthos) compared to linear models (R² = 0.354), successfully capturing the nonlinear responses of biota to stressors such as arsenic in sediments and temperature. It is concluded that natural chemical anomalies in the Titire River act as severe ecological filters, and that artificial intelligence shows promising results in the exploration of new applied tools for environmental management in extreme altoandine ecosystems. Full article