Search Results (1,078)

Zinc oxide (ZnO) nanoparticles are semiconductor nanomaterials widely used in biomedical, environmental, and catalytic applications due to their unique physicochemical properties. However, their increasing environmental release has raised concerns regarding potential toxicity in aquatic ecosystems. In this study, pure ZnO, 1% Au-modified ZnO, and 5% Au-modified ZnO nanoparticles were synthesized via a reflux-assisted method to evaluate the effects of Au incorporation on morphology, crystallinity, optical behavior, surface chemistry, and ecotoxicological responses, using Artemia salina as a marine bioindicator. Structural characterization was performed using high-resolution transmission electron microscopy (HRTEM), electron diffraction, high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X ray spectroscopy (EDS) elemental mapping, while optical and surface analyses were conducted using UV–Vis and Fourier-transform infrared (FT-IR) spectroscopy. Although Au-rich domains were identified, the available data do not allow definitive determination of whether Au is incorporated into the ZnO lattice or present as surface-associated metallic Au. Increasing Au content promoted greater nanoparticle agglomeration and broader particle size distributions while preserving the hexagonal wurtzite ZnO crystalline structure. UV-Vis and FT-IR analyses demonstrated that Au modification altered the optical response and surface chemical environment of the nanoparticles. Toxicological evaluations revealed concentration- and time-dependent toxicity. Pure ZnO nanoparticles exhibited LC₅₀ values of 531.25 ppm after 24 h and 65.15 ppm after 48 h exposure. In contrast, 1% Au-modified ZnO nanoparticles showed reduced toxicity, whereas 5% Au-modified ZnO nanoparticles exhibited increased toxicity after prolonged exposure. These findings demonstrate that Au modification significantly influences the physicochemical properties and biological interactions of ZnO nanoparticles. Full article

The histological segmentation of fish gill lesions is a crucial step in environmental biomarker analysis, as morphological alterations in bioindicator species, such as Sciades herzbergii, provide biologically meaningful evidence of exposure to aquatic contaminants. In this context, gill histology enables the assessment of biomarkers; however, manual lesion quantification remains time-consuming, observer-dependent, and challenging to scale for environmental monitoring programs. Moreover, this task remains challenging due to the presence of heterogeneous textures, fragmented lesion boundaries, low-contrast regions, and staining variability. To address these issues, this study proposes a deep learning framework for the semantic segmentation of epithelial lifting (EL) and hyperplasia (HY) in gill histological images. The proposed model combines a ResNet-50 encoder, an ASPP bottleneck for multiscale contextual aggregation, squeeze-and-excitation-based channel recalibration at the bridge, and a nested U-Net++ decoder with deep supervision. The GillHistDB dataset was also developed for this study, comprising 447 RGB histological images and 29,730 annotated lesions, including 16,855 EL and 12,875 HY instances. The proposed method achieved the best overall performance among the evaluated models in the main overlap-based metrics. At the class level, it obtained Dice values of (0.842 ± 0.055) for EL and (0.684 ± 0.190) for HY, with corresponding IoU values of (0.731 ± 0.080) and (0.548 ± 0.196), respectively. For EL, the method also achieved the highest recall (0.848 ± 0.074), while for HY it reached the highest precision (0.653 ± 0.205) and maintained a high recall (0.767 ± 0.139). These results indicate that the proposed architecture provides an effective and robust solution for gill histological lesion segmentation, while GillHistDB establishes a relevant benchmark to support future studies on environmental biomonitoring, histological biomarkers, and the assessment of aquatic pollution. Full article

Microplastics pose a growing threat to marine ecosystems as they can accumulate in aquatic organisms, interfering with essential physiological processes including reproduction. This study analyzed the effects of short-term exposure (48 h) to two concentrations (0.5 and 1 µg/mL) of 5 µm diameter polystyrene microplastic bead particles in female Mytilus galloprovincialis mussels, a bioindicator species of the Mediterranean Sea. Histological analyses revealed progressive oocyte degeneration and the development of hypertrophic PAS-positive mucous cells, indicative of a stress response, in a dose-dependent manner. Changes in hemocyte classes, which are major effectors of bivalve immunity, were evidenced by the May–Grünwald Giemsa reaction. Biochemical data showed that microplastics increased levels of stress proteins, such as HSP70 and p53, and altered the composition of ovarian glycoproteins. Metabolomic analysis based on ¹H NMR spectrometry revealed significant alterations in metabolites involved in energy (glucose, glycogen, and malonate) and amino acid (branched-chain amino acids arginine, glycine, glutamate, histidine, betaine, and choline) metabolism, suggesting impairment to bioenergetic and antioxidant pathways. Overall, these results suggest that even short-term exposure to polystyrene microplastic beads can alter the ovarian function and metabolism of female M. galloprovincialis, highlighting their vulnerability. Full article

The water bodies of southern Kazakhstan are under strong anthropogenic pressure, underscoring the relevance of their comprehensive research. In the summer of 2025, hydrobiological and hydrochemical studies were conducted at 32 stations across seven water bodies in the region. The dissolved solids content (TDS) ranged from 239.5 to 1472.5 mg/dm³, with favorable oxygen levels and relatively low nutrient levels. Zooplankton comprised 100 species, with rotifers predominating. Zooplankton abundance was 133.2–1289.9 thousand specimens/m³, with a biomass of 0.99–3.94 g/m³. The average number of species per sample varied from 11.5 to 26.7. The Shannon index values ranged from 1.20 to 2.74 bits. The average individual mass of a specimen varied from 0.0011 to 0.0371 mg. Cluster analysis revealed significant differences in the species composition of planktonic invertebrates across water bodies and their biotopes, which, according to the MDS analysis, reflected heterogeneity in external conditions. Analysis of multivariate data showed that the main factors shaping summer zooplankton community structure in the surveyed water bodies were TDS, silicon, and phosphate. The reasons for the identified dependencies between abiotic and biological variables are discussed. The high indicator significance of zooplankton communities in assessing the ecological state of aquatic ecosystems is demonstrated. Full article

Water mites (Hydrachnidia) are diverse, ecologically important arachnids that can serve as effective bioindicators; however, their communities in Mediterranean mountain rivers are scarcely documented. The present study provides a comprehensive analysis of water mite communities in mountain rivers of Serra da Estrela (Portugal), assessing how abundance, genus richness, and community composition vary across seasons, among rivers, and along an elevational gradient. Water mites were sampled in twelve sites belonging to 3 rivers across an elevational gradient and in three seasons. In total, 7296 adult water mites were collected, representing 33 genera and 17 families. Three genera were documented for the first time in Portugal: Albia, Hexaxonopsalbia, and Wettina. Abundance varied with season, being lower in spring (102 ± 35 specimens per site) than in summer (249 ± 73) and autumn (257 ± 83). Genus richness showed a similar pattern, with lower values in spring (9.8 ± 2.0) than in summer (12.2 ± 1.9). Spatial variation among rivers was comparatively minor. The multivariate analysis revealed that community-level changes between seasons, rivers and elevation were driven by only a few genera. The findings help improve the knowledge of Mediterranean mountain water mite communities, shedding light on their seasonal and spatial dynamics. Full article

The analysis of specific habitat conditions involves a systematic assessment of environmental variables such as temperature, hydrology, and vegetation, to clarify species’ ecological requirements and develop conservation strategies. Common approaches include statistical modelling, various Habitat Suitability Index (HSI) models, and GIS-based spatial analyses, which quantify factors like topography, land cover and anthropogenic pressures. Today, machine learning (ML) methods are widely applied across engineering disciplines, including water resources management. In this study, ML methods, particularly model trees, are employed to model and predict key abiotic factors relevant to fish communities. The research focuses on the bioindicator species Barbus balcanicus (brook barbel), which inhabits the middle part of the Sutla River (transboundary river basin between Croatia and Slovenia) and serves as an indicator of ecological conditions in this system. Using ML, models for water depth, water velocity, and water temperature were developed and applied together with SWAT (Soil and Water Assessment Tool) data to determine the HSI for future scenarios to support habitat assessment and water management planning. Full article

A large portion of the Brazilian Cerrado vegetation currently exists as small, disturbed, and isolated fragments. Evaluating the degree of anthropogenic disturbance in certain environments has been successfully achieved using bioindicator insects, particularly ants. This study aims to characterize the epigeic and arboreal ant communities in Cerrado fragments in the southeastern region of Goiás, bordered by agricultural crops, during both the dry and wet seasons, and to correlate these ant communities with the structural characteristics of the forest fragments. Morphospecies richness and ant community structure across the different environments were compared, and bioindicator species were proposed using the Indicator Value (IndVal) method. The ant community structure under the evaluated conditions was significantly altered, indicating effects that extend beyond fragment-specific variables and are associated with the surrounding agricultural landscape. The IndVal analysis suggested two environmental quality indicator species for the ground stratum: Pheidole cf. radoszkowskii and Crematogaster stollii. However, it did not point to any significant indicator species for the arboreal stratum. Ants mediate various functional roles and shifts in the structure of local communities, reinforcing the importance of these insects as bioindicators of environmental quality. Full article

Earthworms possess a highly developed innate immune system based on the coordinated activity of coelomocytes and humoral factors present in the coelomic fluid. These immune components play a central role in host defence against pathogens, maintenance of physiological homeostasis, and adaptation to environmental stressors. Coelomocytes exhibit remarkable functional and morphological diversity, including participation in phagocytosis, encapsulation, extracellular trap formation, cytotoxic responses, wound healing, and regulation of oxidative and osmotic stress. In addition, coelomic fluid contains numerous biologically active molecules, such as lysenin, coelomic cytolytic factor 1, perforin, serine proteases, lysozyme, antimicrobial peptides, and pattern recognition receptors, which contribute to cellular and humoral immune responses. Recent studies have demonstrated that earthworm coelomocytes are highly sensitive to environmental pollutants, including heavy metals, pesticides, nanomaterials, and microplastics, highlighting their importance in ecotoxicological research and soil biomonitoring. Furthermore, antifungal, antimicrobial, anti-inflammatory, antipyretic, and cytotoxic activities associated with coelomocytes and coelomic fluid suggest promising applications in agriculture, biotechnology, and pharmaceutical research. This review summarises current knowledge regarding the classification, characteristics, immune functions, toxicological responses, and applied significance of earthworm coelomocytes and coelomic fluid, with particular emphasis on their role in environmental monitoring and potential biomedical applications. Full article

The adoption of exhaust gas cleaning systems (scrubbers) in maritime transport generates a complex metal-laden washwater that may pose a noteworthy threat to marine ecosystems. This study assessed the acute toxic effects (LC₅₀, 48 h) of four prevalent metals detected in scrubber washwater—vanadium (V), iron (Fe), nickel (Ni), and zinc (Zn)—both individually and as a realistic mixture. For this purpose, multiple life stages of Artemia franciscana (nauplii, juveniles, and adults) and the rotifer Brachionus plicatilis have been tested under laboratory conditions. All metals induced concentration-dependent toxicity, but sensitivities varied through life stages and species tested. The sensitivity to contaminants generally decreased as the organism’s developmental stage progressed. Consequently, three different orders of toxicity can be detected. The order of metal toxicity (from highest to lowest toxicity, based on 48 h LC₅₀ values) was V > Fe > Ni > Zn for nauplii; V > Zn > Fe > Ni for juveniles and adults; and Fe > V > Zn > Ni for B. plicatilis. The Cumulative Toxic Unit (CTU) approach was utilized to compare the predicted additive effect with observed mixture toxicity. This analysis revealed a complex, life stage-dependent interaction; while antagonism dominated in nauplii (suggesting chemical mitigation), juveniles and adults of A. franciscana and the rotifer (B. plicatilis) exhibited significant synergism, amplifying the total toxicity beyond prediction. This study demonstrates that early life stages and small zooplankton are the most sensitive bioindicators of scrubber-related metal contamination, highlighting the potential ecological risk posed by metal-rich, acidic scrubber discharges that may enhance metal bioavailability and toxicity in marine environments. Full article

Brown trout (Salmo trutta L.) is a bioindicator species of ecological integrity in mountain rivers of northern Portugal. Habitat loss and recreational fishing justify sustainable management to balance the conservation and exploitation of these fish populations. In fact, salmonid streams in NE Portugal are low productive watercourses and fish stocking has been continuously demanded by fishermen. However, this most common management action must be analyzed carefully and determined the effective increase for local fisheries, taking into consideration the potential dispersal of stocked fish. The objective of the present study, developed in River Sabor, was to determine short- and medium-term movement and dispersal patterns and habitat preferences of wild and stocked Brown trout, using radio telemetry, during a weekly monitoring 4-month period (October to February 2026; n = 18). Fish was sampled by electrofishing at beginning and the end of the experiment. Twenty-four adult Brown trout, equally distributed by two salmonid sections, and three groups, (1) wild resident (River Sabor) (213–270 mm TL); (2) wild non-resident (from contiguous basin, River Baceiro) (200–375 mm TL) and (3) rear-captivity (Castrelos Fishfarms, ICNF) (227–365 mm TL) fish, were surgically implanted with radio transmitters. Significant differences (KW-H (2;24) = 4.67; p = 0.09) were observed for the dispersal distances, considering fish detected at least in five sampling events, ranging from 120–1437 m for the wild resident stationary group to 192–14,150 m for the stocked mobile group. Moreover, wild non-resident fish displayed higher movement in the upstream direction, in opposition to the downstream movement of stocked individuals. Wild resident and non-resident trout tended to display increased movements during November and December, probably related to spawning activity, showing preferences by riffle and run habitats. Stocked fish were detected in pool habitats (mainly weir reservoirs), exhibiting significantly lower growth rates, and increased movement during January and February, particularly during flood events. These findings are valuable information for managers related to movement patterns, habitat use and stocking management. Full article

This study evaluates the multi-year taxonomic diversity and functional structure of beetle assemblages (Coleoptera) within Sub Arini Park, a historic urban green space in Sibiu, Romania. Following a preliminary baseline and methodological calibration phase in 2023, systematic monitoring was conducted during the 2024 and 2025 seasonal cycles utilizing standardized pitfall trapping across diverse park zones. We explicitly tested two hypotheses: (H1) that long-standing historic park management preserves a resilient and functional insect community structure, and (H2) that local spatial heterogeneity and microhabitat variations significantly drive species distribution. A total of 14,843 individuals belonging to 39 species were analyzed. While total abundance exhibited a slight decrease from 2024 (N = 7112) to 2025 (N = 6551), true diversity metrics (Hill numbers) revealed a significant increase in raw species richness (q = 0) from 30 to 39 species, alongside an enhanced equity of frequent species (Shannon diversity, q = 1, increased from 4.26 to 5.12). Functional guild analysis and multivariate PCA demonstrated a highly structured biocenotic distribution; specialist and hygrophilous species (e.g., Carabus variolosus Fabricius, 1787) were strictly constrained to high-humidity riparian corridors, whereas thermophilous generalists dominated open lawns under high anthropogenic stress. Our spatial analysis identified critical degradation within these heavily managed zones, specifically driven by intensive mowing, soil compaction, and organic debris removal. These findings confirm both hypotheses, revealing that the park operates as a heterogeneous mosaic of ecological refugia rather than a uniform habitat block. Crucially, this study provides a concrete, quantitative basis—derived from empirical thresholds of species richness, abundance shifts, and mapped microhabitat preferences—for implementing nature-based management strategies (such as establishing buffer zones with reduced mowing frequencies, limiting trampling, and retaining coarse woody debris) aimed at mitigating urban biodiversity loss and maintaining vital biological pest control services in Central–Eastern Europe. Full article

This study focused on the spatial and temporal changes in photosynthetic pigment concentrations in the leaves of Ginkgo biloba and their integration into a new bioindicator index, the Pigment Integrity-to-Dust Ratio (PIDR), to assess urban air pollution stress on trees in Budapest, Hungary. High levels of chlorophyll and carotenoids in early summer indicated greater pigment integrity at the moderate-traffic site, whereas there were clear indications of reductions in the high-traffic area. The control site represented a low-traffic, pollution-free baseline. Chlorophyll concentrations dropped in the traffic-exposed leaves, and there were increased levels in the formation of pheophytin. It is thought that these reductions were caused by city stress. Responses of pigments were also variable at the moderate site, perhaps due to some form of recovery or adjustment in the study’s time frame. The observed negative relationships between selected pollutants and PIDR suggested that pollutant exposure was associated with pigment degradation and foliar dust deposition, although these associations should be interpreted as exploratory. The Air Pollution Tolerance Index (APTI) was significantly different between the pollution-exposed sites and the control, reflecting physiological tolerance in chronically exposed trees rather than directly measuring pigment damage. Therefore, the APTI and PIDR provide complementary information. Overall, the PIDR appears to be a promising exploratory bioindicator of physiological stress response, based on pigment concentration changes and dust deposition. Full article

Sustainable agricultural technologies are essential to respond to environmental and social pressures, ensuring the maintenance of global food security. Therefore, there is an urgent demand for more sustainable agricultural practices that promote soil quality, as this factor directly impacts the global economy. Agricultural yield is directly associated with soil health and fertility. The use of organic waste serves as a source of essential nutrients for plants, increasing soil organic matter, contributing to the improvement of soil physical and chemical properties, as well as increasing crop yield. Based on this context, this research aimed to evaluate the effects of incorporating organic waste aiming to mitigate the oxidative damage in maize plants grown under different levels of soil fertility (low, average, and high), evaluating soil and plant, more specifically chemical, physiological, biochemical, and morphological responses. In soil, organic waste promoted significant increases in the activities of arylsulfatase and β-glucosidase and improved the chemical parameters, including cation exchange capacity, soil organic matter, base saturation, and sum of bases. The application of organic waste, regardless of fertility level, improved the nutritional status in maize plants, increased concentrations of photosynthetic pigments, maximized the photochemical efficiency and photosynthesis rate. In plant metabolism, the results demonstrated that organic waste promoted significant increases in plant antioxidant defense, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, minimizing the oxidative stress on photosynthetic machinery, especially in plants cultivated on soil with low fertility. Therefore, this research proves that organic waste mitigates the negative impacts associated with nutritional starvation, improves soil health and fertility, favors the maintenance of redox metabolism, and stimulates photosynthesis in maize plants cultivated in low-fertility soil. Full article

Livestock intensification drives biodiversity loss, making impact quantification essential. Life Cycle Assessment (LCA) can evaluate whether regenerative practices, such as silvopastoral systems, mitigate this loss, but it requires specific characterization factors (CFs). In this pilot study, we applied the countryside Species-Area Relationship (SAR) model to derive the first invertebrate-specific CFs using dung beetles (Scarabaeinae). From field surveys, we calculated intensity-specific CFs for potential species loss (PSL/m²) in pastureland and cropland. We assessed biodiversity impacts per 1 kg calf live weight (LWC) across three livestock regimes: native silvopastoral (NSP, minimal land use), intensive silvopastoral (ISP, light land use), and monoculture (MC, intense land use). Results show high dung beetle affinity for NSP. The CFs distinguished impact intensity levels: MC had the highest PSL per area (6.76 × 10⁻¹⁰ PSL/m²), followed by ISP (5.93 × 10⁻¹⁰ PSL/m²) and NSP (4.99 × 10⁻¹⁰ PSL/m²). However, normalizing by yield reversed this trend: MC showed the lowest impact per 1 kg LWC (7.64 × 10⁻⁸ PSL/kg LWC), ISP was intermediate (1.06 × 10⁻⁷ PSL/kg LWC), and NSP had the highest impact (1.31 × 10⁻⁷ PSL/kg LWC). Incorporating upstream feed production significantly increased the overall biodiversity footprint, underscoring the need for comprehensive system boundaries. Integrating broader biodiversity components and landscape context remains essential to fully capture livestock management effects. Full article

Introduction: Coastal fishes can adapt to water warming and hypoxia; however, acute tolerance does not necessarily predict longer-term performance and survival. This may be especially important in sedentary, site-faithful species with limited escape to escape increasingly unfavorable habitats. We assessed the climate-related stress responses of the Lusitanian toadfish, Halobatrachus didactylus, a benthic estuarine fish from the Northeast Atlantic, to water warming and hypoxia. Objectives: We aimed to determine the aerobic energy budget, thermal limits (CTmax), and critical oxygen tension (Pcrit), as well as blood indicators of metabolism, altered physiology and systemic stress, as proxies for whole-organism homeostatic state, thereby informing future ecophysiological assessments and bioindicator development in a context of environmental change. Methodology: We determined standard, routine, and maximum metabolic rates; aerobic scope; and critical thermal maximum (CTmax) and critical oxygen (Pcrit) thresholds on a set of 134 individuals ranging from 12 to 160 g in weight. On a different set of individuals (n = 48; 76.3 ± 2.6 g; 16.1 ± 0.18 cm), we simulated 30 days of seasonal scenarios combining low and high temperature with normoxia or hypoxia, followed by integrated metabolic, hematological, biochemical, and multivariate analyses. Results: Acute trials showed high short-term resilience: H. didactylus had an exceptionally low standard metabolic rate and routine metabolic rate, high CTmax (34.82 ± 0.66 °C), and strong hypoxia tolerance (Pcrit 0.59–1.97 mg O₂ L⁻¹), although smaller individuals were more sensitive. After 30 days, however, warming more than doubled standard and routine metabolic rates, while warm hypoxia reduced metabolic output relative to warm normoxia, consistent with metabolic depression under compounded stressors. This treatment also showed shifts in glucose, liver mass, red blood cell count, and hematocrit, identifying warm, oxygen-poor water as the most physiologically costly scenario for this species. Conclusions: Together, these results show that high acute tolerance does not guarantee resilience to climate change. In sedentary fishes, survival may depend less on surviving extremes than on maintaining energetic balance, oxygen transport capacity, and physiological homeostasis in increasingly warm, oxygen-poor coastal habitats. Full article