Search Results (70)

Environmental DNA (eDNA) and environmental RNA (eRNA) are increasingly used in aquatic biomonitoring, but they serve different ecological purposes. eDNA can persist in biofilms, reflecting accumulated environmental signals, while eRNA is short-lived and indicates metabolically active communities. To assess their suitability for evaluating stream health, we compared benthic diatom assemblages derived from both eDNA and eRNA. Alpha diversity indices revealed negligible differences between the two nucleic acid types, although total read abundance showed a small effect size (Cliff’s δ = 0.207). Taxonomic overlap was significant, with 70% of species shared between the two sources, though several genera displayed source-specific patterns. Community analyses indicated that eRNA-based assemblages had greater internal consistency and clearer differentiation between groups. The Trophic Diatom Index application revealed that eDNA captured cumulative water quality conditions, while eRNA provided a more sensitive reflection of current ecological states. These findings highlight that eDNA offers broad taxonomic coverage, whereas eRNA delivers a higher resolution of active ecological responses. By integrating both markers, we can achieve a more comprehensive assessment of long-term environmental history and current stream health, enhancing the accuracy of diatom-based bioassessment frameworks. Full article

Phytoplankton are key indicators of water quality and low-cost tools for freshwater monitoring, yet their diversity and ecological drivers remain poorly documented in the Tropical Andes. This study provides the first national-scale, multi-ecosystem assessment of net phytoplanktonic communities (including microalgae and cyanobacteria), across Ecuador, integrating physicochemical, multivariate, and geospatial analyses. Eighteen lakes and rivers from three biogeographic regions and a wide altitudinal gradient were surveyed, yielding 129 taxa, 77 identified at species level, the most comprehensive checklist reported to date for Ecuador. Community structure showed a clear lentic–lotic differentiation driven by hydrodynamic contrasts, while the absence of distance–decay patterns indicated high dispersal and environmental filtering pattern rather than spatial structuring. Anthropogenic pressure acted as a secondary gradient: pristine high-Andean lakes were dominated by desmids and diatoms, whereas agricultural and urban basins showed chlorophyte and potentially toxic cyanobacterial assemblages. Palmer’s Index detected organic pollution but underestimated eutrophication in endorheic, geochemically enriched lakes. Land-use effects presented strong basin-scale signals in lakes but weak correlations in rivers due to overriding hydromorphological constraints. These findings establish a robust spatial baseline for freshwater bioassessment in the Andes, demonstrating the value of phytoplankton as effective, low-cost indicators readily applicable to national water-quality assessment programs. Full article

Urban rivers provide vital ecosystem services, benefiting both nature and people, yet they are heavily impacted worldwide, exhibiting similar symptoms collectively known as the Urban Stream Syndrome (USS). This study assessed the ecological status of the Someșul Mic River, located in Cluj-Napoca, Romania’s second-largest and rapidly developing city, through the lens of benthic invertebrate communities, recognized for their strong bioindicator value. Six sites along the main river course, four adjacent sites on tributaries, and an artificial canal were analyzed. Our findings revealed the presence of USS at all sites; however, contrary to expectations, the mainstem sites showed higher water quality and greater taxonomic and functional diversity of zoobenthos. The primary drivers of this pattern were the proportion of coarse sediments and flow velocity, with river width playing a lesser role. Based on these results, eight mitigation strategies were proposed, aligned with the river ecosystem services. Their implementation could improve the ecological condition across the river, floodplain, and catchment levels, involving both scientists and the general public. Overall, the study provides a management-oriented framework for future river restoration initiatives in a growing city and a comparative reference for urban river assessments. Full article

Benthic macroinvertebrates are widely used for river ecosystem health monitoring, yet challenges remain in non-wadable rivers, particularly regarding sampling effort. We evaluated hand-net sampling efficiency at three sites along the Danjiang River (a Yangtze River tributary) by analyzing taxa richness across taxonomic levels under varying replicate numbers. In total, 61 taxa (41 families) of benthic macroinvertebrates were identified. Non-metric multidimensional scaling analysis indicated no significant spatiotemporal variation in community composition. However, sampling effort increased, and the benthic macroinvertebrate taxa richness at both genus/species and family levels also increased. At eight sample replicates, the taxa accumulation curve at the genus/species level did not show an asymptote, with the observed richness reaching 67–80% of the predicted values calculated by Jackknife 1. In contrast, the family-level curve exhibited a clear asymptotic trend, with the observed richness reaching 82–100% of the predicted values. As sampling effort increased, bias decreased and accuracy improved, particularly for family-level taxa. Additionally, the BMWP scores also increased with the sampling effort. When the replicate number was no less than six, the BMWP reached stable assessment grades for all cases. From the perspective of bioassessment in non-wadable rivers, the hand net is suitable for collecting benthic macroinvertebrates. However, there is a risk of underestimating taxa richness due to insufficient sampling effort. Using family-level taxa can partially mitigate the impacts caused by insufficient sampling efforts to a certain extent, but further validation is needed for other non-wadable rivers (e.g., those with soft substrates). In conclusion, our research results indicate that six replicate hand-net samplings in non-wadable hard-bottom rivers can be regarded as a cost-effective and reliable sampling method for benthic macroinvertebrate BMWP assessment. This strategy provides a relatively practical reference for the monitoring of benthic macroinvertebrate in the same type of rivers in China. Full article

Mayfly nymphs are reliable indicators of aquatic habitat quality, and whilst their presence and relative abundance are often used in bioassessment schemes, it is important to recognise that these attributes are affected by the sampling method employed. To test these effects, we sampled stream habitats for mayflies using two commonly used techniques in a standardised setup: aquatic sweep nets and manual collection from stones. These methods resulted in different success rates in detecting certain taxa depending on their biological traits (preferred microhabitat and locomotion type). Whilst species lists generally overlapped between the two methods, they yielded different values of total abundance, taxon richness, Shannon–Wiener’s diversity index, assemblage saprobic index, and general community structure. These results suggest that reliance on a single collection method is prone to yield only partial information for ecological assessments and emphasises the importance of employing a sampling technique that is appropriate for the study question and goals or combining more than one method. Based on these findings, we outline the scientific justifications for using each sampling method. Full article

Municipal wastewater effluent (MWWE) is a common source of nutrient enrichment and provides a route for emerging substances of concern (ESOCs) to enter aquatic systems. Community composition and abundance metrics of benthic macroinvertebrates are commonly utilized to assess ecological impacts associated with nutrient enrichment; however, the responses of these metrics in systems with diverse chemical mixtures from MWWE, are not well understood. This study specifically addresses the effects of cumulative loading of tertiary-treated MWWE through responses in benthic macroinvertebrate communities in experimental control and treatment streams. Treatment streams used source river water previously exposed to upstream wastewater treatment plants but with an additional 5% by volume tertiarily treated MWWE, while control streams used only source river water. Surbers and artificial substrate rock baskets were used to examine impacts on both established and colonizing benthic communities, respectively. No significant differences were observed between the control and treatment streams in any of the community metrics of well-established benthic communities. In contrast, significant decreases in colonizing taxon diversity and evenness were found between treatment and control streams. The dominant taxa (most abundant family, by percentage of sample) in the community, often filter feeders, significantly increased in percentage of the total community in treatment streams. This response was consistent with a nutrient enrichment effect, with no evidence of ESOC related toxicity. This study highlights the need for bioassessment programs to utilize approaches involving varied in-situ sampling methods and controlled exposure systems to gain a better understanding of how various stages of community-level development are impacted by urban pollutants such as MWWE. Full article

Reservoirs serve functional purposes such as irrigation and power generation. However, concerns are raised due to the alterations of the connected riverine ecosystems. Chironomidae (Diptera), a diverse aquatic macroinvertebrate group, are vital to the functioning of ecosystems and serve as water quality indicators. Their holometabolous development includes the pupal stage after four larval stages. The chironomid pupal skin (exuvia) is used in environmental assessments, where the Chironomid Pupal Exuvial Technique (CPET) is a recognized standard. The CPET method is adaptable to different freshwater environments and here was applied in the study of 28 man-made lakes in the Pannonian Lowlands and Dinaric Western Balkan Ecoregion in Croatia to obtain information on chironomid diversity and analyze the potential influence of environmental factors on the chironomid community. The lake surface was skimmed with an exuvial hand net (mesh size of 300 µm) along the lake edge with a transect length of 10 m in the area of accumulated debris of organic and inorganic matter. Individual exuviae were mounted in a Berlese mounting medium and identified by morphological characteristics to the lowest taxonomic level. During the study, 5698 chironomid pupal skins were collected, and 141 taxa (including 97 species) belonging to five subfamilies were identified. The tribe Tanytarsini comprised 40% of the identified taxa, with Paratanytarsus spp. being the most abundant. In the Dinaric ecoregion, Paratanytarsus bituberculatus dominated, while Microchironomus tener and the genus Cricotopus were the dominant taxa in the Pannonian ecoregion. Community structure in the Pannonian ecoregion was influenced by total organic carbon (TOC) and orthophosphates (PO₄³⁻), indicating higher anthropogenic pressure compared to the Dinaric ecoregion, where water conductivity influenced Chironomidae assemblages. The research has provided valuable and useful information on the chironomid diversity in man-made and highly altered water bodies, as some of the most vulnerable aquatic habitats to anthropogenic influence. The CPET method could be a useful tool for the ecological studies and bioassessment of water quality in Croatia. Full article

The bioavailability of heavy metals in soil is a crucial factor in determining their potential uptake by plants and their subsequent entry into the food chain. Various methods, including traditional chemical extractants and the diffusive gradients in thin films (DGT) technique, are employed to assess this bioavailability. The bioavailability of heavy metals, particularly cadmium (Cd) and lead (Pb), is also influenced by soil texture and their concentrations in the soil solution. The primary objectives of this experiment were to compare and correlate the assessment of the Cd and Pb bioavailability using the DGT technique and traditional extractants across two soil textural classes: sandy clay loam (SCL) and clay loam (CL) at two contamination levels: aged contaminated (NC) and artificially contaminated (AC). The specific objectives included assessing the bioavailability of Cd and Pb at different growth stages of the wheat plant and correlating the DGT-based bioassessments of Cd and Pb with their concentrations in various plant parts at different growth stages. This study also compared the effectiveness of the DGT method and traditional extraction techniques in assessing the bioavailable fractions of Cd and Pb in soil. The regression analysis demonstrated strong positive correlations between the DGT method and various extraction methods. The results showed that the wheat plants grown in the AC soils exhibited lower root, shoot, and grain weights compared to those grown in the NC soils, indicating that metal contamination negatively impacts plant performance. The concentrations of Cd and Pb in the wheat tissues varied across different growth stages, with the highest levels observed during the grain filling (S3) and maturity (S4) stages. It is concluded that the in situ assessment of Cd and Pb though DGT was strongly and positively correlated with the Cd and Pb concentration in wheat plant parts at the maturity stage. A correlation and regression analysis of the DGT assessment and traditional extractants showed that the DGT method provides a reliable tool for assessing the bioavailability of Cd and Pb in soils and helped in developing sustainable soil management strategies to ensure the safety of agricultural products for human consumption. Full article

Large rivers are difficult to sample due to their size yet critical to monitor because humans heavily rely upon and alter them. Aquatic invertebrates are commonly used to assess the ecosystem quality of streams, but methods to sample large rivers are underdeveloped. We sampled aquatic invertebrates using a Hess sampler and rock baskets in the Snake River near Jackson, Wyoming, USA. Hess samples collected more aquatic invertebrate taxa and a higher proportion of Ephemeroptera, Plecoptera, and burrowing taxa. Rock baskets collected a higher proportion of Trichoptera, filterers, and clinging taxa. Bioassessment metrics differed between sampling methods; richness, diversity, evenness, Ephemeroptera, Plecoptera, and Trichoptera (EPT), and Hilsenhoff’s biotic index produced higher values in Hess samples, and percent EPT was higher in rock baskets. Non-metric multidimensional scaling and analysis of similarity indicated that the samplers collected different assemblages (p < 0.001). The standard error of total invertebrate density was smaller and most taxa were collected with seven replicate samples. Understanding how sampling methods alter the aquatic invertebrates collected will help managers develop monitoring protocols that are best suited to the river and collect the most unbiased invertebrate assemblages. Full article

Shallow lakes according to the alternative states theory may present extremely different environmental conditions, clear water with abundant growth of macrophytes and turbid water with cyanobacterial blooms. The deterioration of water quality led to visible changes within submerged macrophytes and thus in available habitats for plant-associated biocenosis. Larvae of chironomids are the most numerous and widely distributed macroinvertebrates. Since benthic chironomids are used in the monitoring of environmental changes and in paleolimnological research, epiphytic chironomids are not well known in this regard. The larvae can be used as indicators of lake macrophyte status. The present study focuses on plant-associated chironomids of a group of ten shallow lakes of the Polesie region (eastern Poland). The lakes were classified with alternative states theory as macrophyte-dominated (MD), phytoplankton–macrophyte-dominated (PMD) and phytoplankton-dominated (PD). The domination structure of epiphytic chironomids showed significant changes between lake types, with the highest abundance of Paratanytarsus austriacus in MD lakes, Endochironomus albipennis in PMD lakes and Cricotopus sp. (gr. sylvestris) in PD lakes. The highest mean density was noted in PD lakes while the highest species diversity (values of Shannon–Wiener index) in PMD lakes. Moreover, environmental variables (macrophyte biomass, Secchi disc depth, chlorophyll-a and TP) differentiating lake types were used in RDA analysis to evaluate their effect on chironomid taxa distribution. Next, the variables with a significant effect on specific chironomid taxa were used in multivariate regression analysis. The results led to the creation of a model of distribution of chironomid taxa with regard to lake type. Full article

This study explores the impact of anthropogenic land use changes on the macroinvertebrate community structure in the streams of the Cangshan Mountains. Through field collections of macroinvertebrates, measurement of water environments, and delineation of riparian zone land use in eight streams, we analyzed the relationship between land use types, stream water environments, and macroinvertebrate diversities. The results demonstrate urban land use type and water temperature are the key environmental factors driving the differences in macroinvertebrate communities up-, mid-, and downstream. The disturbed streams had lower aquatic biodiversity than those in their natural state, showing a decrease in disturbance-sensitive aquatic insect taxa and a more similar community structure. In the natural woodland area, species distributions may be constrained by watershed segmentation and present more complex community characteristics. Full article

Activated blood coagulation factor X (FXa) plays a critical initiation step of the blood-coagulation pathway and is considered a desirable target for anticoagulant drug development. It is reversibly inhibited by nonvitamin K antagonist oral anticoagulants (NOACs) such as apixaban, betrixaban, edoxaban, and rivaroxaban. Thrombosis is extremely common and is one of the leading causes of death in developed countries. In previous studies, novel thiourea and oxime ether isosteviol derivatives as FXa inhibitors were designed through a combination of QSAR studies and molecular docking. In the present contribution, molecular dynamics (MD) simulations were performed for 100 ns to assess binding structures previously predicted by docking and furnish additional information. Moreover, three thiourea- and six oxime ether-designed isosteviol analogs were then examined for their drug-like and ADMET properties. MD simulations demonstrated that four out of the nine investigated isosteviol derivatives, i.e., one thiourea and three oxime ether ISV analogs, form stable complexes with FXa. These derivatives interact with FXa in a manner similar to Food and Drug Administration (FDA)-approved drugs like edoxaban and betrixaban, indicating their potential to inhibit factor Xa activity. One of these derivatives, E24, displays favorable pharmacokinetic properties, positioning it as the most promising drug candidate. This, along with the other three derivatives, can undergo further chemical synthesis and bioassessment. Full article

High-elevation tropical streams are under increasing threat from human activities and climate change. Specifically, Ecuadorian Andean streams require priority actions such as bioassessment (e.g., biodiversity and functional ecology of macroinvertebrates) in order to generate adequate environmental management policies. Therefore, we investigated the distribution and composition of the macroinvertebrate taxa and their functional feeding groups in relation to the environmental variables in the Antisana river basin (Andean–Ecuadorian Region). We sampled macroinvertebrates from 15 locations to assess ecological conditions (ECs), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes, the Andean Biotic Index (ABI) and the Andean–Amazon Biotic Index (AAMBI). Results indicate that dissolved oxygen saturation, elevation, nutrient concentration and conductivity contributed significantly to the composition of the taxa and functional feeding groups (FFGs). Taxa diversity and FFGs were more abundant in the best EC sites. Shredders (SH) were, overall, dominant and abundant at sites with medium-high ECs. Scrapers constituted the second most prevalent assemblage, exerting dominance at moderate ecological conditions (high altitude and high oxygen saturation). Collector–gathers (CGs) are less sensitive to contamination than the previous two groups but were equally abundant at medium-high EC sites. Collector–filterers (CFs) and parasites (PAs) were less abundant, although the presence of the former was slightly related to better environmental conditions. Predators (PRs) were almost absent throughout the study, but they were collected from poor EC sites. CGs, PAs and PRs showed more tolerance to the presence of human disturbances (e.g., hydraulic constructions or slope erosion). The BMWP-Col index seems to be the best fit for this ecosystem, showing a significant difference in FFG between the index classes, compared to the other indices evaluated. The results of this investigation may be regarded as a fundamental starting point and used in future bioassessment work in other similar ecosystems, particularly high-altitude tropical Ecuadorian streams. Full article

Incorporating diatoms species and their autecology from reference stream conditions is essential for improving the accuracy of North American diatom bioassessments. This study documents a voucher flora and physicochemical conditions of Upper Three Runs Creek (UTRC), a tributary to the Savannah River that has been protected from heavy human activity for the last 50 years. The algae of UTRC and its watershed have been monitored continuously during this time by the Academy of Natural Sciences in Philadelphia to detect potential impacts from the Savannah River Site and Plant Vogtle. Standard protocols were used to sample and denote substrate types and preferences and to estimate relative abundances of diatom species. Data from artificial substrates (diatometers) were compared to composite samples. Phenotypic plasticity of taxa from Gomphonema parvulum, Eunotia incisa, and Tabellaria flocculosa sensu lato species complexes were considered in biodiversity metrics. We provide documentation of these separations. A total of 297 species/operational taxonomic units (OTUs) were recorded. For 2018 samples, Eunotia rhomboidea accounted for 8.3% for separated taxa methods and G. parvulum sensu lato (16.2%) dominated for combined taxa methods. Luticola goeppertiana (5.4%) was the most abundant taxon in the 1956 samples. The 1956 composite samples species richness means were greater and significantly greater than those for other sample types (ANOVA, df = 3, p = 0.004). The recounted 1956 composite samples had the highest species richness (153) followed by the left diatometer (129). At the same location, the right and left diatometers were not similar. Both methods (diatometers and composite sampling) are useful when assessing species richness. Diatom community composition indicated an acidic and highly oxygenated environment. Full article

This research describes fish assemblages and associated aquatic ecosystem degradation patterns in the Büyük Menderes River, one of Turkey’s most important Anatolian basins. Using standard electrofishing, 44 river sites were sampled throughout the basin accounting for the distribution and abundance of 20 native and seven non-native species, totaling 13,535 fish specimens. At each sampling site, anthropogenic pressures were assessed, and information was gathered to determine the degree of human-induced degradation that may affect fish and their habitats; each site was scored on the basis of a site quality index (SQI). Using the best-available relatively less-degraded river sites, cluster analyses of the samples defined six fish assemblage river types. Further classification of all fish samples utilizing bipartite network analysis resulted in comparable assemblage groupings. The European Fish Index (EFI+) with minor adaptations was applied for assessing river ecological integrity at all sampled sites in order to explore the utility of this widely used index. The EFI+ index results correlated with scores of the SQI but provided a very narrow assessment range, thus failing to accurately and consistently assess the severity of anthropogenic degradation. We recommend a new multimetric index to be developed for the Western Anatolian Ecoregion, of which this basin is a part. The data and insights gained from this exercise may help continue fish-based indicator development for policy-relevant management and conservation in Turkey’s rivers. Full article