Search Results (537)

Urban freshwater ecosystems are exposed to multiple anthropogenic pressures, but their effects on macroinvertebrate communities may vary depending on waterbody type and surrounding land use structure. This study analysed macroinvertebrate communities in three waterbody types of the Belgrade functional urban area. Land use was classified into agricultural, artificial, and semi-natural areas, and evaluated using LUI and HHI indices. A total of 187 macroinvertebrate taxa were recorded, indicating high diversity despite the urban setting. Community composition differed among waterbody types, with non-wadeable rivers characterised by a high proportion of Oligochaeta, wadeable rivers by a greater contribution of insects, and canals by the dominance of crustaceans. Land use further influenced community structure: semi-natural areas were associated with a higher proportion of crustaceans, artificial areas with Chironomidae, and agricultural areas with Oligochaeta. Alpha diversity was highest in wadeable rivers, while beta diversity showed that compositional differences were driven by species turnover. SPEAR indices indicated stress-related differences among waterbody types. CCA showed that community variation was associated with conductivity, temperature, oxygen saturation, pH, BOD, TOC, AOX, and phosphate. Overall, macroinvertebrate communities in the Belgrade urban area are shaped by the combined effects of waterbody type, land use structure, and local environmental conditions. Full article

Rice paddies function as temporary wetlands that provide important habitats for diverse aquatic macroinvertebrates. However, the relative roles of regional climatic conditions and invasive species in shaping macroinvertebrate communities remain insufficiently understood. This study investigated the effects of regional temperature variation and the invasive apple snail Pomacea canaliculata on aquatic macroinvertebrate communities in rice paddies across South Korea. Aquatic macroinvertebrates were surveyed annually from 2021 to 2024 in five regions distributed along a latitudinal gradient, and additional local-scale comparisons were conducted between rice paddies with and without P. canaliculata. A total of 42 species comprising 24,524 individuals were recorded. Community composition differed significantly among regions and variation partitioning indicated that regional temperature explained 17.5% of the community variation in paddies containing P. canaliculata, whereas the snail explained 2.3%. Several dominant aquatic insect species exhibited distinct temperature-associated distribution patterns, with Rhantus suturalis and Hydrochara affinis showing negative relationships with temperature and Sternolophus rufipes showing a positive relationship. In contrast, P. canaliculata had little influence on aquatic insects but reduced overall macroinvertebrate diversity through its negative effects on native gastropod assemblages. These findings demonstrate that regional temperature and P. canaliculata influence rice-paddy macroinvertebrate communities through different ecological pathways. Regional temperature primarily affects the distribution of several dominant aquatic insect species, whereas P. canaliculata alters community diversity by reducing native gastropod populations. This study provides ecological evidence for predicting the combined impacts of climate warming and biological invasion on rice-paddy ecosystems. Full article

We address the challenging problem of predicting the biological quality of a water body based on a set of environmental and management-related drivers. While modelling approaches for predicting water quality from hydrological and pollution-load variables are well established, analogous tools for predicting biological status remain less consolidated. Both components are nevertheless required within the Water Framework Directive to assess ecological status (ES) and support restoration planning. This paper concentrates on the latter challenge by presenting an experience developed over four heavily impacted rivers in Regione Lombardia (Northern Italy). Rutinary environmental, hydromorphological and biological data were systematized to develop a predictive framework linking management-related pressures to the macroinvertebrate component of ecological status. A rule-based classifier, denominated MacroSimply, was developed and compared with alternative statistical and machine learning approaches: logistic regression, a classification tree (CHAID), and a multilayer perceptron neural network. The tested models exhibited different strengths and weaknesses: Logistic regression provided a good balance between predictive performance and interpretability; the classification tree generated transparent threshold-based decision rules; and the neural network captured potentially complex non-linear relationships, albeit with reduced interpretability. MacroSimply achieved predictive performance comparable to the alternative approaches, and performing even higher reliability, while maintaining full transparency of the structure and a direct connection between predictors and management actions. The proposed framework was subsequently implemented in a spreadsheet-based tool to be easily used in restoration planning exercises. Although the obtained model should not be considered the definitive modelling solution even for our particular case, the results suggest that the adopted rule-based approach represents a working, valuable option preferrable to more complex data-driven methods when interpretability, reproducibility and practical applicability are key requirements for environmental management. Full article

This study provides a preliminary baseline characterization of macroinvertebrate assemblages colonizing floating islands installed in two NE Portuguese river reaches with contrasting anthropogenic and hydromorphological conditions: the urban, weir-influenced Fervença River and the more rural, reservoir-like Côa reach within a former dam-work area. A single campaign in February 2025 combined water characterization and macroinvertebrate sampling on islands and adjacent margins. Fervença showed higher mineralization and microbiological contamination, but a more varied assemblage dominated by tolerant taxa. Côa showed better water quality but strong Astacidae dominance. Results indicate colonization only; robust replicated monitoring is needed before inferring ecological improvement. Full article

Riverine mercury biomagnification is most frequently studied via metrics such as the trophic magnification factor (TMF), the biomagnification factor (BMF) and the trophic magnification slope (TMS). However, these metrics prove problematic in lotic systems dominated by benthic macroinvertebrates because short food chains, the frequent lack of fish, patchy basal production and marked spatial heterogeneity obscure the signal that they are meant to extract. We argue that stable isotopes of carbon and nitrogen (δ¹³C, δ¹⁵N) are not merely optional enhancements but are a prerequisite for a mechanistic understanding of the transfer of methylmercury (MeHg). Nitrogen isotopes distinguish among trophic positions not as categories, but as gradients, whilst carbon isotopes reflect the underlying pathways increasingly seen as defining how MeHg enters food webs. Invertebrate studies, published more recently, report systematically lower magnification levels compared to community-based studies and become far more comprehensible when carbon source and trophic pathways are made explicit, with Hg isotopes (δ²⁰²Hg, Δ¹⁹⁹Hg) providing supplementary data about mercury sources and processing. To be able to carry out reliable river monitoring, such frameworks require clarity in choices of background value, discrimination factors and statistical methods. Full article

Climate change models point to a possible rise in air temperature, ranging from 2 °C to 4 °C. Global changes will therefore have a particularly pronounced effect on the functioning of shallow water bodies known as peat ponds, i.e., habitats formed after peat extraction in peatlands. However, the extent of this impact is still unknown. The main objective of the study was to determine the impact of water level and water physicochemical properties on the functioning of selected groups of aquatic organisms in peat ponds of different origins. The study was conducted in spring, summer and autumn of the years 2024 and 2025, in 10 peat ponds with different trophic status and typology, located in the Polesie National Park in eastern Poland. Considerable fluctuations in water levels, resulting from a scarcity of precipitation, accelerated the drying out and overgrowth of peat ponds, particularly the alkaline and acidic types. Within the zoocoenotic communities, a significant decline in the abundance of planktonic species and an increase in the abundance of littoral or periphytic species were recorded (F = 6.24, p < 0.015). Regarding trophic structure, an increase in the abundance of mixotrophic species and a decrease in the abundance of top-level predators were observed. Hydrological changes were reflected in an increase in species richness and abundance of communities of organisms with broad ecological tolerance (mainly ciliates), and a decrease in the number of species and abundance of planktonic crustaceans and macroinvertebrates. The RDA model explains over 84% of the total variability, indicating excellent model fit to the data and a strong correlation between environmental variables and species composition. Based on p values, water level, temperature, pH, and COD were selected as significant variables, with conductivity, O₂, and P_tot demonstrating less statistical significance. Peat ponds ecosystems can serve as an excellent model system for studying the impact of intensifying climate change on the functioning of shallow water bodies. Full article

As an artificial–natural composite ecosystem, polders face increasingly prominent internal and surrounding water environment problems under sustained strong human activities. To systematically assess the water ecological health status of polders around Dongting Lake, this study took four typical polders around Dongting Lake as research subjects, and two seasonal surveys of benthic macroinvertebrates were carried out in July and December 2024. Through analyses of community structure characteristics and correlations with key environmental factors, the Trophic Level Index (TLI), Water Quality index (WQI), Shannon–Wiener index of benthic macroinvertebrates, and Benthic Macroinvertebrates Index of biotic integrity (B-IBI) were selected to establish an entropy-weighted Bayesian model for comprehensive evaluation of the current ecological health of Dongting Lake polders. In 2024, a total of 47 benthic macroinvertebrate species were found in Dongting Lake polders, including 25 species in the summer and 36 species in the winter. The main groups were Gastropoda, Insecta, and Bivalvia, and the community composition did not show significant seasonal or spatial differences. The benthic macroinvertebrate community structure in the summer was mainly influenced by TN/TP, NO₃⁻-N, WD, Tur, and Chl.a, suggesting eutrophication as a critical concern, while in the winter it was mainly regulated by WSW, WT, Tur, and DO, highlighting hydrological conditions as pivotal. The entropy-weighted Bayesian assessment indicated an overall aquatic ecological health status of “moderate” in 2024, with summer conditions superior to those in the winter and notable spatial heterogeneity observed in winter sampling sites within ditches, among which Polder Chengxi exhibited the best condition, while Polder Junshan and Polder Xiangbin Nanhu showed degraded states. Notably, Polder Junshan (JS2 and JS3) displayed clear signs of ecological degradation during the winter, warranting immediate initiation of targeted restoration measures. This study provides a systematic diagnosis and scientifically grounded evaluation of aquatic ecological health in Dongting Lake polders, offering a robust theoretical framework and empirical data for future water environmental protection strategies and ecological restoration practices. Full article

Geodiversity, particularly topographical gradients, significantly influences ecosystem function by creating heterogeneous environmental conditions. This study examined how local-scale microtopography and litter bag perforation affected leaf litter decomposition rates in a humid-temperate secondary forest. We categorized microtopography into ridge, valley, southwest slope, and northeast slope, with relative height differences of around 20 m. Using the litter bag method comparing non-perforated (1 mm mesh) and perforated (with 6 mm holes) bags, we measured leaf litter mass loss and moisture content of Quercus serrata over 6 and 12 months. While microtopography caused only slight differences in leaf litter moisture content, it significantly influenced decomposition rates. Leaf litter mass loss was lower in valley microtopography compared to the southwest slope and ridge microtopography. We infer that topographical differences in unmeasured microclimatic factors, such as solar radiation and soil temperature, may have potentially driven these spatial variations in decomposition. Furthermore, because the litter bag perforation did not significantly promote further mass loss, our results suggest that baseline decomposition driven by organisms capable of passing through the 1 mm mesh (e.g., microbes and meso/microfauna) might have been sufficiently high in this environment. These findings highlight that local-scale microtopographical differences enhance the spatial heterogeneity of leaf litter decomposition in forest ecosystems. Full article

High-mountain lotic ecosystems in the tropical Andes are increasingly threatened by agricultural expansion and seasonal hydrological variability. This study evaluates structural water quality shifts and benthic macroinvertebrate community assembly across an environmental degradation gradient in the La Chorrera micro-basin (Boyacá, Colombia). A weighted multiplicative Water Quality Index (mWQI), originally developed in previous literature, was implemented and validated alongside biotic scores (BMWP/Col) and Canonical Correspondence Analysis (CCA) across 16 sampling points during contrasting wet and dry seasons. The results demonstrate that intense precipitation during the wet season introduces a volumetric dilution effect, maintaining high ecological quality scores (mWQI > 80.0) even in deeply modified agricultural sectors. Conversely, severe baseflow contraction during the dry season triggers pollutant concentration, driving total phosphorus to hyper-eutrophic peaks (9.20 mg/L) and forcing a complete mathematical collapse of the index (mWQI = 0.00). The CCA biplot confirmed that seasonal chemical filters combined with hypoxia (<60% oxygen saturation) eliminate highly responsive macroinvertebrate orders (Ephemeroptera, Plecoptera, Trichoptera), leading to absolute dominance of hypoxia-tolerant opportunists (Chironomidae and Oligochaeta). The benthic community shifted from physical stress (sedimentation) during the wet season to chemical stress (nutrient toxicity and oxygen depletion) during the dry season. The multiplicative framework effectively isolates localized ecological tipping points, providing a high-sensitivity baseline tool for targeted watershed restoration in tropical alpine regions. Full article

Brachymystax lenok tsinlingensis is an endangered salmonid endemic to China. Traditional trapping methods frequently fail to detect this rare fish in low-density mountain streams, hampering evidence-based conservation. Here, we employed environmental DNA quantitative PCR (eDNA-qPCR) with species-specific primers to assess the spatial biomass distribution of this species in the Zhouzhi Heihe River. Concurrently, we surveyed plankton, benthic macroinvertebrates, and physicochemical water parameters. eDNA detected the target species at 12 of 14 sites, with reliable quantification achieved at 9 sites, suggesting that the method may be more effective than conventional trapping for detecting this species under the studied low-density conditions. eDNA-derived relative biomass exhibited pronounced spatial heterogeneity, ranging from 6.0 × 10⁻⁴ to 1.5 × 10⁻² g/cm³. Water depth showed a significant positive association with biomass (r = 0.5347), whereas phytoplankton Shannon diversity (a measure of species richness and evenness) was significantly negatively correlated (r = −0.5447). Flow velocity displayed a negative trend that did not reach statistical significance (r = −0.5009). Plankton and benthic communities indicated overall ecological conditions but did not directly explain the observed spatial variation in fish biomass. These findings indicate that the spatial pattern of B. lenok tsinlingensis is primarily shaped by local physical habitat structure, with deeper, hydraulically more complex channel units serving as key microhabitats. eDNA-qPCR thus represents an effective, low-disturbance monitoring tool for this endangered cold-water fish and provides a scientific basis for targeted habitat protection and restoration. Full article

Introduction: Biological invasions constitute one of the main threats to freshwater ecosystems, causing significant ecological changes through the introduction of exotic species that compete with or prey upon native species. In Portugal, the introduction and spread of exotic species in lotic and lentic ecosystems, such as pike (Esox lucius), European catfish (Silurus glanis), and largemouth bass (Micropterus salmoides), all top predators, may have a big impact on autochthonous species. In contrast, bleak (Alburnus alburnus), European perch (Perca fluviatilis), and common carp (Cyprinus carpio) compete aggressively for food resources. In the Sousa River basin, gudgeon (Gobio lozanoi) is considered an exotic species with potential ecological impact, with the minnow (Phoxinus phoxinus) stand having been recently identified in Portugal and, so far, recorded only in this river basin, and not yet being classified as an invasive species in Portugal. Public knowledge regarding invasive aquatic biodiversity remains a significant bottleneck for conservation. Because recreational angling is a prominent dispersal vector, initiatives that directly target this community are relevant. Objective: The aim is to carry out a bibliographic review on the exotic ichthyofauna species present in the Sousa River, with special focus on the invasion potential of the minnow (P. phoxinus). Methodology: The literature review was conducted based on the ScienceDirect, Springer Nature Link, and Fauna Norvegica databases, selecting publications between 2006 and 2025 concerning relevant studies on the potentially invasive characteristics of the minnow (P. phoxinus). The methodology is based on the analysis of studies regarding the impacts caused on riparian ecosystems. Results: The species P. phoxinus presents a generalist diet and high adaptive capacity, allowing it to colonise new habitats and compete aggressively with native species for trophic resources. Its presence is associated with negative impacts on brown trout populations (Salmo trutta), reducing growth and productivity, especially in mountain ecosystems. Increased species density also causes a significant decrease in benthic macroinvertebrate biodiversity. Studies conducted in the Douro basin indicate that the arrival of minnow in Portugal resulted from human action, probably associated with its use as live bait in recreational fishing. Conservation programmes use diverse tactics to bridge the awareness gap. Recent initiatives feature electrofishing demonstrations to visually differentiate species, theatrical performances, and even culinary show-cooking events using invasive predators like the European catfish to promote harvesting. Conclusions: The potential transition of P. phoxinus into an exotic and invasive species may be associated with the ecological pressure exerted on native communities, particularly through competition for trophic resources, highlighting the need to assess its dispersion in the Sousa basin and its impacts on fish fauna and benthic macroinvertebrates. It is important to do more sampling to understand its real distribution in the Sousa Basin. Additionally is important to explain to recreational anglers and the general population the impacts of fish transfer and the adverse effects of invasive species on freshwater Portuguese ecosystems. Full article

Springs are environmentally stable habitats that are refugia for specialized species. Springs at Monte Generoso, Monte Bar, and Monte Tamaro in the southern Swiss Alps were investigated to understand how they are affected by human activities and environmental changes. We conducted (a) a temporal comparison of five springs at Monte Generoso, which were first sampled in 2011 and re-sampled in 2023 and (b) a spatial comparison of 19 springs of the three mountains. Physical and chemical parameters were measured, ecomorphology and anthropogenic impacts were evaluated, and macroinvertebrates were sampled. Springs at Monte Generoso changed along a temperature gradient. EPT-taxa shifted towards euryoecious taxa owing to environmental changes. The spatial comparison showed differences between the mountain summits driven by electrical conductivity and water temperature. These differences were mainly evident for Crenobia alpina and in the occurrence of Niphargus cf. thuringius in Bar and Tamaro as well as Drusus alpinus in Tamaro. Springs at Monte Generoso were the least diverse and exhibited the highest water temperature, possibly owing to the higher utilization pressure. Spring specialists were present even in heavily modified springs. This spatio-temporal analysis provided insights into the pressure on springs in the southern Swiss Alps, emphasizing the importance of a site-specific protection of these precious habitats. Full article

River restoration is increasingly promoted as a nature-based solution, but evidence of its ecological effectiveness in mountain gravel-bed rivers remains limited. Macroinvertebrate responses to hydromorphological restoration are variable and are still rarely evaluated using an integrated approach combining taxonomic, biotic index, and trait-based components. This study examined whether the hydromorphological restoration of the upper Raba River was associated with measurable environmental and ecological differences between the restored and unrestored sections. Six river sections were analyzed, including three restored and three unrestored sections. The environmental characterisation included hydromorphological and physicochemical variables. Benthic macroinvertebrates were sampled in shallow marginal and main-current habitats, and the analyses included assemblage metrics, biotic indices, taxonomic composition, indicator taxa, and functional traits. The restored sections showed greater channel complexity, including a larger active channel zone, a larger number of active channels, and a coarser substrate. These differences were accompanied by higher Shannon diversity, higher values of the Polish Biological Monitoring Working Party index (BMWP-PL), a higher percentage of individuals of Ephemeroptera, Plecoptera and Trichoptera (%EPT), distinct assemblage composition, and shifts in indicator taxa and selected functional traits. The results highlight the value of multidimensional assessment frameworks to evaluate the effects of restoration on mountain rivers. Full article

Emerging contaminants constitute a growing pressure on river ecosystems due to their persistence, chemical diversity, and ecotoxicological effects. The objective of this study was to analyze the presence of these compounds in muscle tissue across a range of aquatic species, including benthic fish (Gobio lozanoi, Cobitis sp.), nektonic species (Salmo trutta, Lepomis gibbosus), diadromous species (Anguilla anguilla, Petromyzon marinus, in the larval stage), generalist species (Pseudochondrostoma duriense), and crustaceans (Procambarus clarkii). Concentrations were determined using LC-MS/MS, grouping the compounds into different chemical families (e.g., pharmaceuticals, personal care products, industrial compounds, and other emerging contaminants). The results showed significant differences both among species and among compound families. At the interspecific level, Petromyzon marinus (larvae) exhibited the highest total concentrations, followed by Salmo trutta and benthic species such as Gobio lozanoi and Cobitis sp. Intermediate values were observed in Pseudochondrostoma duriense and Lepomis gibbosus, while Anguilla anguilla showed moderate levels. Procambarus clarkii displayed notable accumulation, especially of sediment-associated compounds. Analysis by compound families revealed distinct patterns: pharmaceutical and personal care compounds showed a relatively homogeneous distribution among species, whereas more hydrophobic and industrial compounds tended to accumulate in species with higher lipid content or greater benthic exposure. In particular, benthic species (lamprey larvae, gudgeon, spined loach, and crayfish) showed higher accumulation of sediment-associated compounds, confirming their role as contaminant reservoirs. Lamprey larvae, which exhibit filter-feeding behavior and remain buried in fine sediments for several years, showed high accumulation of multiple contaminant families, highlighting the importance of this life stage as an indicator of environmental contamination. The results demonstrate the coexistence of different accumulation mechanisms: (i) direct exposure to sediment, (ii) trophic biomagnification, and (iii) accumulation linked to the physicochemical properties of the compounds. This combined approach by species and contaminant families allows for a more comprehensive assessment of the ecological status of the system. Finally, the relevance of including multiple taxonomic groups and life cycle stages in monitoring programs is emphasized, especially in vulnerable species such as Petromyzon marinus. Full article

Shallow eutrophic lakes recover from nutrient loading on time scales ranging from less than one year to many decades, yet whether this range is set by the lake or by the biological response group has rarely been quantified within a single monitoring framework. We assembled a five-year (2020–2025) quarterly monitoring panel from three shallow Yangtze-floodplain lakes (Lake Changhu, Lake Liangzihu, and Lake Honghu; 15 stations, 21 quarters) and applied a panel mixed-effect distributed lag model (PME-DLM) to estimate the lag-response windows of phytoplankton and benthic macroinvertebrate densities against five water-quality drivers. Cross-lake consistency was tested with a station-resampled bootstrap, and the contributions of water quality, season, and lake identity to community variation were resolved by three-table variation partitioning. The PME-DLM resolved a 3-month temperature window for phytoplankton and 9–15 month chlorophyll a and temperature windows for benthic communities, while total nitrogen and total phosphorus were non-significant in either group. Cross-lake bootstrap intervals on window width overlapped substantially across the three lakes, whereas cross-group differences in window centre and shape were an order of magnitude greater. Variation partitioning further showed a mirror-image structure in which phytoplankton variation was dominated by the pure water-quality fraction (12.2%) and benthic variation by the water-quality × season joint fraction (5.8%). Within the resolution of this five-year, three-lake panel, group-level differences in lag-response time scale were more apparent than lake-level differences and provide a quantitative basis for matching restoration assessment cadence to pelagic versus benthic recovery. Full article