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The disturbance in river ecosystems caused by reservoirs and dams has become a critical topic, attracting increasing attention. However, the extent to which reservoir and dam construction and operation impact downstream river ecosystem health and ecosystem service functions is not fully understood. This research examines the Xiaolangdi Reservoir and the Lower Yellow River (LYR) ecosystem in China as a case study. We analyzed the complex material and energy flows in the LYR ecosystem using emergy theory and developed a set of emergy-based indicators for the quantitative assessment of river ecosystem health and services under reservoir operation interference. The results indicate that the total natural capital and environmental endowments of the LYR ecosystem have remained relatively stable after the operation of the Xiaolangdi Reservoir, with an increase in renewable emergy input. The ecosystem's vigor decreased slightly, while the biomass emergy diversity index remained stable. However, the total emergy inputs increased significantly, with external feedback inputs becoming the most important emergy source for the LYR ecosystem. The resilience of the LYR ecosystem improved, with a significant increase in emergy density and a decrease in the emergy sustainability index. These findings suggest that although the river ecosystem continues to provide supporting services to human society, the extent of these services has diminished compared to pre-perturbation levels. In this research, a methodology for analyzing the impact of key reservoir operations on the ecosystem health and services of a large river is proposed to provide support for large river sustainable development studies. [ABSTRACT FROM AUTHOR]

Climate change is interacting with water resource pressures to alter the frequency, severity and spatial extent of drought, which can thus no longer be considered a purely natural hazard. Although particularly severe ecological impacts of drought have occurred in drylands, its effects on temperate ecosystems, including rivers, are also considerable. Extensive research spanning a diverse range of UK rivers offers an opportunity to place the effects of past drought in the context of intensifying climate change and to examine the likely effects of future drought in a typically cool, wet country. Here, drought manifests instream as deficits in surface water, modified flow velocities, and—increasingly—partial or complete drying of previously perennial and naturally non‐perennial reaches. As a result, drought causes declines in the taxonomic and functional biodiversity of freshwater communities including microorganisms, algae, plants, invertebrates and fish, altering ecological processes and associated benefits to people. Although freshwater communities have typically recovered quickly after previous UK droughts, an increase in drought extremity may compromise recovery following future events. The risk of droughts that push ecosystems beyond thresholds to persistent, species‐poor, functionally simplified states is increasing. Research and monitoring are needed to enable timely identification of rivers approaching such thresholds and thus to inform interventions that pull these ecosystems back from the brink. Management actions that support natural flow regimes and promote natural processes that diversify instream habitats, including drought refuges, are also crucial to support biodiversity within functional river ecosystems as they adapt to a changing world. This article is categorized under:Water and Life > Nature of Freshwater EcosystemsWater and Life > Stresses and Pressures on EcosystemsWater and Life > Conservation, Management, and Awareness [ABSTRACT FROM AUTHOR]

Increasing human pressures threaten fish diversity, with potentially severe but unknown consequences for the functioning of riverine food webs.Using a 17‐year dataset from multi‐trophic fish communities, we investigated the long‐term effects of human pressure on the diversity and food web functioning. Combining metabolic scaling and ecological network principles, we calculate the annual energy fluxes through trophic compartments (top‐carnivore, mesocarnivore, detritivore and omnivore). Energy fluxes link trophic compartments, and thus represents food web functions such as carnivory, omnivory, herbivory and detritivory.Species richness across all trophic compartments was positively associated with energy flux. However, species richness decreased over time, as did the energy flux at the whole‐network level, which was reduced by 75%. Human pressure negatively affected both species richness and energy flux. Moreover, the negative impacts of human pressure on energy flux have intensified over time.Our results illustrate how human pressure can reduce diversity and erode the energy flux through food webs, with negative implications for the ecosystem functioning. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

This paper describes two datasets: species occurrences, which were determined by environmental DNA (eDNA) metabarcoding and their associated DNA sequences, originating from a research project which was carried out along the Houdong River (猴洞坑), Jiaoxi Township, Yilan, Taiwan. The Houdong River begins at an elevation of 860 m and flows for approximately 9 km before it empties into the Pacific Ocean. Meandering through mountains, hills, plains and alluvial valleys, this short river system is representative of the fluvial systems in Taiwan. The primary objective of this study was to determine eukaryotic species occurrences in the riverine ecosystem through the use of the eDNA analysis. The second goal was, based on the current dataset, to establish a metabarcoding eDNA data template that will be useful and replicable for all users, particularly the Taiwan community. The species occurrence data are accessible at the Global Biodiversity Information Facility (GBIF) portal and its associated DNA sequences have been deposited in the European Nucleotide Archive (ENA) at EMBL-EBI, respectively. A total of 12 water samples from the study yielded an average of 1.5 million reads. The subsequent species identification from the collected samples resulted in the classification of 432 Operational Taxonomic Units (OTUs) out of a total of 2,734. Furthermore, a total of 1,356 occurrences with taxon matches in GBIF were documented (excluding 4,941 incertae sedis, accessed 05-12-2023). These data will be of substantial importance for future species and habitat monitoring within the short river, such as assessment of biodiversity patterns across different elevations, zonations and time periods and its correlation to water quality, land uses and anthropogenic activities. Further, these datasets will be of importance for regional ecological studies, in particular the freshwater ecosystem and its status in the current global change scenarios.The datasets are the first species diversity description of the Houdong River system using either eDNA or traditional monitoring processes.

A healthy water ecosystem within a river basin is essential for maintaining ecological security, preserving species diversity, and ensuring sustainable socio-economic development. Unfortunately, human activities have significantly threatened the health of water ecosystems in various basins. Consequently, timely restoration and targeted protection of damaged river ecosystems have become crucial objectives in watershed management. As a prerequisite and cornerstone for river protection and management, assessing river ecological health has emerged as a primary focus in current research. In this study, we selected the Wei River Basin, a representative area of the Yellow River Basin, as our research subject. We identified multiple influencing factors, including society, biology, water quality, and habitat, which collectively impact this semi-arid region. To assess the overall impact of these factors on ecological health, we developed a comprehensive River Ecological Health Assessment Index (REHAI) system. The research findings indicate that the Wei River system, as a whole, is currently in a healthy state, while the Jing and Luo River systems are classified as sub-healthy. Furthermore, we observed variations within the Wei River system itself; the upper reaches of the Wei River exhibit higher levels of health compared to the middle reaches, whereas the water environment in the lower reaches is the most compromised. This degradation can be attributed to downstream subsidence, increased pollution, and rapid urbanization. By establishing a river ecosystem health assessment methodology and conducting a comprehensive evaluation of the health status of river ecosystems, this paper puts forward management recommendations for river basins. These findings provide a scientific basis for the sustainable utilization of water resources in river basins and promote the harmonious coexistence of humanity and nature. [ABSTRACT FROM AUTHOR]

Community assembly can change over time following variations in connectivity among habitats. Previous studies have demonstrated the influence of seasonal pulse floods on community structures by facilitating species dispersal, but the effects of short‐term flash floods have been poorly investigated. We investigated fish community structures before and after a short‐term flood in drainage ditches of paddy fields in the Kita River basin, Japan. The study sites were classified into three connectivity types, "Transient" (connected only during the flood, with a temporally disappearing vertical gap between drainage ditches and downstream rivers), "Connected" (always connected, without the vertical gap), and "Disconnected" (always not connected, with the vertical gap). The abundance of Misgurnus anguillicaudatus, the only species that dispersed from paddy fields to drainage ditches, increased after the flood irrespective of the connectivity types, although the total abundance of the other species significantly increased after the flood only in the "Transient" sites. The dissimilarity of species composition between the (n − 1)‐th and n‐th surveys at each site was consistently low in the "Connected" and "Disconnected" sites, whereas it rose just after the flood and gradually declined in the "Transient" sites. Species composition was significantly different among the connectivity types, indicating that some fish species need stable connectivity even during the non‐flood period. The results showed that the short‐term flood facilitated fish dispersal from paddy fields by the increased water discharge and that from downstream rivers by the temporary removal of vertical gap, emphasizing the importance of hydrological connectivity for biodiversity conservation in an agricultural landscape. [ABSTRACT FROM AUTHOR]

ABSTRACT Riverine islands are widespread alluvium wetlands developed in large rivers, and bacterial communities are crucial to their ecological function, yet their assembly processes are rarely addressed. The ecosystem services provided by the middle and the lower Yangtze are primarily threatened by pollution discharge from agricultural land use, and resource overutilization (e.g., embankments), respectively. Here, we assessed bacterial community assembly processes and their drivers within riverine islands in the middle Yangtze River (MR islands) and those in the lower reach (LR islands). A significant distance–decay relationship was observed, although the turnover rate was lower than that of the terrestrial ecosystem with less connectivity. Deterministic and stochastic processes jointly shaped community patterns, and the influence of stochastic increased from 26% in MR islands to 59% for those in LR islands. Meanwhile, the bacterial community in MR islands was controlled more by inorganic nitrogen availability, whereas those in LR islands were governed by pH and EC, although those factors explained a limited fraction of variation in the bacterial community. Potential indicator taxa (affiliated with Nocardioides and Lysobacter) characterized the waterway transport pollution. Overall, our study demonstrated that bacterial community dissimilarity and the importance of dispersal limitation increased concurrently along the flow direction, while distinct local factors further determined bacterial community compositions by selecting habitat-specificity taxa and particularly metabolism function. These findings enhanced our understanding of the mechanisms driving changes in bacterial communities of riverine islands subject to increased anthropogenic impacts.IMPORTANCERivers are among the most threatened ecosystems globally and face multiple stressors related to human activity. However, linkages between microbial diversity patterns and assembly processes in rivers remain unclear, especially in riverine islands developed in large rivers. Our findings reveal that distinct factors result in divergent bacterial community compositions and functional profiles in the riverine islands in the middle Yangtze and those in the lower Yangtze, with substantial differentiation in deterministic and stochastic processes that jointly contribute to bacterial community assemblages. Additionally, keystone species may play important metabolic roles in coping with human-related disturbances. This study provides an improved understanding of relationships between microbial diversity patterns and ecosystem functions under environmental changes in large river ecosystems.

The health of watershed ecology is mutually constrained by the sustainable development of the regional economy and society, and health assessment helps to identify the ecological status quo. As one of the “ethnic corridors”, the Bailong River has become a region of human solid interference. Therefore, this study constructed an indicator evaluation system to reflect rivers' natural attributes and functionality by analyzing candidate indicators' sensitivity, principal components, and independence. The weight of the indicators was determined using the Analytic Hierarchy Process combined with expert opinions. The ecological status of the Bailong River was evaluated through field monitoring data, and ecological restoration suggestions were proposed. The results show that Bailong River's comprehensive score is 58.27, indicating sub-health. The constructed evaluation system includes thirteen indicators, of which 53.84% are in an ideal state, 15.39% are healthy, 7.69% are sub-health, 15.39% are unhealthy, and 7.69% are pathological, with weak spatial heterogeneity. The evaluation results of the guidelines show that the state of “cleanliness” and “service” is ideal, “circulation” and “life” are healthy, and “physical structure” is worrying. Based on this, the ecological restoration and protection of the Bailong River in the future should focus on the following aspects: improving methods and theories, restoring the habitat environment of the river, ensuring water quantity, improving water quality, and conserving fish species. This study can provide necessary theoretical support for the ecological restoration of severely disturbed water-deficient rivers and lakes in northern China.

The Maestrazgo and the Sierra de Gúdar in Teruel are made up of a great diversity of ecosystems, among which, in addition to the riparian forest and the aquatic ecosystems on which this study focuses, the forest ecosystems spread over several bioclimatic floors particularly stand out. The objective of this paper is twofold. On the one hand, it seeks to evaluate the state of conservation of one of the territories with the greatest natural wealth in southern Aragon, namely the fluvial ecosystem of the Guadalope River in its upper section, and on the other hand, it proposes a protection framework with greater legal imperative such as that pertaining to natural parks, which this province does not currently have. To do this, the methodology will be based on the consultation of the few specialized bibliographies on this study area, and on the other hand, it will determine the quality of fluvial habitats based on the construction of two indicators: the QBR on quality of the riparian forest and the IHF on fluvial habitats. The results show that despite the fact that this territory does not currently have any environmental protection framework other than three natural monuments, a ZEPA and a ZEC, it has enough values to be declared a natural park, which would be the first in this area. [ABSTRACT FROM AUTHOR]

River ecosystems have become fragile due to river flow alterations in the wake of expending structural controls triggered by the ever-increasing demands of freshwater. The efforts to alleviate the effects of river flow alterations have paved the way for the emergence and expansion of the concept of e-flows. The role of e-flows in ecosystem protection and water resources management is not yet fully understood and practiced. This review summarizes the historical evolution of the concept of e-flows and recaps its assessment methods; analyzes the impacts of river flow alterations; indicates the challenges e-flows have been facing and identifies the gaps in the focus of e-flows research. A total of 303 articles published since 2010 were collected and systematically assessed. Most of the publications are focused on describing the effects and management of river flow alterations. According to the findings of this meta-analysis, less attention is given to basin-scale, social and policy aspects of e-flows. Furthermore, little consideration is given to the part played by groundwater in e-flows along with the roles of e-flows in maintaining the health of floodplains and e-flows of intermittent rivers and ephemeral streams. HIGHLIGHTS E-flows help to ensure the health of the river ecosystem and ecosystem services.; Many articles have been published in the last two decades concerning e-flows, but issues related to basin/regional-scale e-flows; e-flows of intermittent rivers, ephemeral streams and groundwater; and the role of e-flows for the health of floodplains and transboundary e-flows issues are limited.; The impacts of river flow alterations are diverse and dispersed. This review brings many impacts of river flow alterations together.;

River ecosystem biodiversity and biogeochemical processes are shaped largely by riverside vegetation and soil. Moreover, river ecosystems provide ecological services influenced by the surrounding vegetation and soil interactions. However, the mechanisms by which artificially remediated plants (ARPs) and riparian soil interact to provide these benefits are still unclear among various ARPs. This study fills this gap and examines the impact of ARPs along the riparian zones of Three Gorges Dam (TGD) in Chongqing City, China. We sampled four varieties of ARPs from the Ruxi River Basin in the TGD. These varieties included Cynodon dactylon, Hemarthria altissima, Taxodium disticum, and Salix mastudana. Our results indicated substantial changes in soil physicochemical parameters. Comparably, T. distigum contains significantly higher soil chemical contents. Interestingly, principal component analysis explained almost 100% of the variance for all plant species in this study. Moreover, different vegetation types and soil chemical properties were positively correlated using Pearson correlation analysis (p

Riparian topographical features can drive a suite of ecological indicators (EIs) that shape the river ecosystem. The mechanisms that EIs reflect provide several ecosystem services. We know little about the responses of EIs (indicators of plant cover, regeneration, exotics, habitat, erosion, and stressors) to the changing stream-channel width, riparian width, and elevation of the lengthy drawdown zones (upstream, midstream, and downstream) of long rivers. We have discovered that changing topographical characteristics affect riparian buffer areas differently by using a rapid field-based method with 297 transects in inundated regions along the Yangtze River and other 36 linked tributaries in China. Changing stream-channel widths was most effective on downstream EIs and the least effective at midstream. The exotic parameters were the most affected (with a range of −0.36 < r

This study was carried on Upper Mazowe River in Zimbabwe which connects with Luenha River in Mozambique, which is a tributary of the Zambezi River. Zambezi River is the fourth longest river in Africa flowing into the Indian Ocean, which makes the study of regional and global interest. Heavy metal aqueous speciation has received relatively little attention compared to sediment speciation in the Upper Mazowe River, and yet heavy metal behaviour and fate in surface waters are greatly affected by the heavy metal chemical form in solution. The aim of the study was to determine the elemental composition and speciation of heavy metal(oid)s. This study focused on water and sediment speciation of Al, As, Cu, Hg, Mn, Fe, and Pb using Visual MINTEQ Version 3.1 computer modelling and sequential extraction techniques. Twenty-eight different water column elemental species, comprising 3, 2, 3, 1, 7, 7 and 5 species each, and 35 sediment phase elemental species, comprising 6, 6, 6, 2, 6, 5, and 4 species each for Al, As, Cu, Hg, Mn, Fe, and Pb respectively, were identified. Of note is the fact that Hg, mainly derived from artisanal gold mining activities, exists entirely as the fulvic acid complex, FA2Hg (aq), and As exists as H3AsO3 and H2AsO3− in the water phase. Exchange equilibrium reactions across the water-sediment interface were observed for Mn2+, Fe2+, Cu2+, and Pb2+. Reactions leading to the formation of the species were identified. Species interactions within the water column and sediment phase and species interrelationships with physicochemical parameters are discussed. H3AsO3 formation is predicted to be temperature sensitive and the aluminium hydroxide-fulvic acid complex /FA2(AlOH) (aq) is oxic favourable.

Our study provides a retrospective evaluation of the perturbances of the opencast mining on the small river. Based on a standard 'before-after-control-impact' approach, we assess the impact of disturbances on aquatic ecosystems. For this purpose, we used IHA (Index of Hydrological Alteration) statistics to fully quantify the impact of open-pit mine on flow regimes of small-to-medium-size rivers. The analysis results in flow data captured in the 33 parameters of the range variability approach (RVA) and five ecological flow components (EFC). This approach helped us comprehensively evaluate the alteration in the flow regime in areas of open-pit mining on the example of the Noteć River, a typical lowland river. We conclude that the level integrated hydrologic alterations to this river under the influence of the groundwater depression cone and water from the mine dewatering are high, as assessed by the RVA and EFC methods. Specifically, this work uses the IHA framework to verify the necessity of including a specific group of indicators. Our analysis shows that for the post-impact period on the investigated river, the functioning of the river ecosystem was degraded. One of the EFC components completely disappeared at both water gauge stations. There were also profound hydrologic alterations, such as increased frequency or duration of “extreme low flows” at one station; at the second station, “high flow pulses” occurred more frequently. More than 65 % of the altered parameters in five IHA groups were modified drastically. In the river section affected by the groundwater depression cone, both the minimum and maximum flows decreased by 20 % to 55 %. In the section where water from the mine dewatering is fed in, the minimum flows changed by + 170 to + 230 %. The use of the IHA tool provides an opportunity for environmental flow restoration of water conditions in degraded post-mining areas.

Per- and polyfluoroalkyl substances (PFASs) have attracted worldwide attention due to their high stability, refractory degradation, and bioaccumulation. The Dongjiang River is one of the most important water sources in the Pearl River Delta region. It flows from Jiangxi Province to Guangdong Province and finally into the Pearl River, providing domestic water for cities such as Guangzhou, Shenzhen, and Hong Kong. In this study, 17 PFASs in water, sediment, and fish in the Dongjiang River Basin in southern China were investigated using high-performance liquid chromatography-mass spectrometry. Total PFAS concentrations ranged from 20.83 to 372.8 ng/L in water, from 1.050 to 3.050 ng/g in sediments, and from 12.28 to 117.4 ng/g in fish. Among six species of fish, Oreochromis mossambicus (mean: 68.55 ng/g) had the highest concentration of PFASs, while Tilapia zillii (36.90 ng/g) had the lowest concentration. Perfluorooctanoic acid (PFOA) predominates in water and sediments, while perfluorooctanesulfonic acid (PFOS) predominates in fish. Long-chain perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) showed higher bioaccumulation, and the field-sourced sediment-water partition coefficients (Kd) and bioaccumulation factors (BAFs) of PFASs increased with the length of perfluorocarbon chains. PFAS concentration in the lower reaches (urban area) of the Dongjiang River is higher than that in the upper and middle reaches (rural area). The calculated hazard ratio (HR) of PFOS and PFOA levels in fish in the Dongjiang River Basin was far less than 1; hence, the potential risk to human health was limited. [ABSTRACT FROM AUTHOR]

The work contains generalized approaches and features of anthropogenic load on the basins of small rivers within Lutsk town. The reasons for the deterioration of quality of the surface water in Lutsk are considered. The assessment of the level of anthropogenic load on river basins in the city of Lutsk was carried out. A number of practical actions are presented that could stop anthropogenic processes and improve the use of small rivers.

The quality of the surface water along the Kunhar River in Mansehra district, KPK Pakistan was assessed for ten water samples stations. A variety of parameters indicating water quality including physicochemical parameters, nutrients, heavy metals, and antibiotic residues were measured for both the rainy and dry seasons, the two main tropical seasons in Mansehra, using the standard methods. Kunhar River, one of the local drinking water sources, was studied to assess the heavy metal content, health risk assessment, and its suitability for human consumption. Health risk assessment for all the stations indicated that there is no particularly dangerous single heavy metal, but their cumulative effect is indicated by the hazard index. Concentrations of metals in water have a trend of decreasing in water, indicating that the accumulation of metals can affect the water chemistry of aquatic systems due to any physical or chemical process in the system. Greater consideration should be given to the variety of metals in relationship to multivariate analyses, suggesting that the industrial and residential activities were more important contributors to the pollution of the Kunhar River than the agricultural activities in Mansehra district. Such metals pose risks to aquatic life. HIGHLIGHTS In the Kunhar River, seasonal fluctuations in the levels of nutrients, toxic substances, as well as certain antibiotics were identified.; The study revealed that domestic activities caused significantly more environmental damage to the Kunhar River than agricultural practices.; High-pollution sites of the Kunhar River have been affected by human settlement.;

Assessing the hydromorphological conditions of watercourses is a requirement of the Water Framework Directive (WFD) and national river status monitors (e.g., in Poland,the State Environmental Monitoring, and Water Monitoring coordinated by Chief Inspectorate of Environmental Protection). This paper evaluates the hydromorphological status of 10 watercourses (30 measurement sections) in Poland based on the multimetric Hydromorphological Index for Rivers (HIR). A new approach to the delineation of the river valley (small watercourses) is proposed. An analysis of the influence of river valley management on the value of HIR and its components was carried out using statistical methods (basic statistics, Mann–Whitney U Test and Ward's cluster analysis). In addition, the relationship between the components of the HDS (Hydromorphological Diversity Score) and HMS (Hydromorphological Modification Score) was analyzed (Spearman's Rank Correlation Coefficient). HIR values for the watercourse sections ranged from 0.553 to 0.825. HDS values ranged from 27.5 to 75.5 and HMS from 2.0 to 17.5. The results of the basic statistical analyses showed slight differences between the two river valley delineation methods. The Mann–Whitney U Test showed a significant difference in the test significance level of the HDS, HMS and HIR for the river valley delineation methods. Spearman's rank correlation analysis showed that most of the HDS and HMS parameters components had a low degree of correlation. The juxtaposition of the two methods for delineating a river valley and its influence on the HIR allows for a better understanding of the interdependence between its parameters. [ABSTRACT FROM AUTHOR]

This study assessed the spatio-temporal dynamics of the phytoplankton community in backwaters of the Ketar River, central Ethiopia, in relation to water quality and macrophyte coverage. Phytoplankton samples and physicochemical information were collected at six sites along the river over 1 year (December 2017 to November 2018). Phytoplankton was collected using a 15-μm mesh net. A total of 56 species belonging to three algal phyla were identified; the most diverse phylum was Bacillariophyta (35 species), followed by Chlorophyta (13 species) and Euglenophyta (eight species). Bacillariophyta had the highest abundance and contributed 80.08% of the total phytoplankton abundance. Site 6 in the downstream portion had the highest abundance and greatest diversity of phytoplankton species. The algal phyla present showed significant differences in species diversity and abundance both spatially and temporally. Redundancy analysis results revealed that the spatial distribution of phytoplankton in the river positively correlated with pH, electrical conductivity, dissolved oxygen and nitrate-nitrogen, while water temperature and total suspended solids correlated negatively. Some indicators of organic pollution suggest that the water quality of the river is progressively declining, meriting close monitoring. [ABSTRACT FROM AUTHOR]

A modern approach to understanding biodiversity variation is to deconstruct beta diversity patterns into the local contribution to beta diversity (LCBD–uniqueness in species composition of a site) and species contribution to beta diversity (SCBD–influence of a species in the beta diversity within the region) which is a good approach to improving knowledge of the beta diversity. We carried out this work to understand the pattern and relationship of LCBD, SCBD and the rarity of the spider community in the riparian habitat of the Ganga River. We calculated the correlation between LCBD and species richness of both all the species and rare species. We used the first order and second order terms to find the relationship between SCBD and the number of sites occupied by species and to find the relationship between SCBD and the index of rarity for all the species and three ecological guilds of spiders. We found that the LCBD of the spider community had a significant relationship with total species richness but not with rare species richness. Spider species with intermediate occurrence across the study sites contributed more to SCBD values than species with high and low occurrence. We found that the index of rarity of spider species had a significant relationship with SCBD values. The non-parametric permutational multivariate analysis of variance (PERMANOVA) tests revealed no significant differences in the distribution of different ecological guilds of spiders between the study sites. The integrated LCBD and SCBD approach can be used to carry out effective conservation and restoration programmes that preserve the structural, functional, and ecological diversity of spiders, as well as other biological communities in riparian ecosystems. [ABSTRACT FROM AUTHOR]

Introduction: Currently there are sparse regulations regarding the discharge of antibiotics from wastewater treatment plants (WWTP) into river systems, making surface waters a latent reservoir for antibiotics and antibiotic resistance genes (ARGs). To better understand factors that influence the fate of ARGs in the environment and to foster surveillance of antibiotic resistance spreading in such habitats, several indicator genes have been proposed, including the integrase gene intI1 and the sulfonamide resistance genes sul1 and sul2. Methods: Here we used quantitative PCR and long-read nanopore sequencing to monitor the abundance of these indicator genes and ARGs present as class 1 integron gene cassettes in a river system from pristine source to WWTP-impacted water. ARG abundance was compared with the dynamics of the microbial communities determined via 16S rRNA gene amplicon sequencing, conventional water parameters and the concentration of sulfamethoxazole (SMX), sulfamethazine (SMZ) and sulfadiazine (SDZ). Results: Our results show that WWTP effluent was the principal source of all three sulfonamides with highest concentrations for SMX (median 8.6 ng/l), and of the indicator genes sul1, sul2 and intI1 with median relative abundance to 16S rRNA gene of 0.55, 0.77 and 0.65%, respectively. Downstream from the WWTP, water quality improved constantly, including lower sulfonamide concentrations, decreasing abundances of sul1 and sul2 and lower numbers and diversity of ARGs in the class 1 integron. The riverine microbial community partially recovered after receiving WWTP effluent, which was consolidated by a microbiome recovery model. Surprisingly, the relative abundance of intI1 increased 3-fold over 13 km of the river stretch, suggesting an internal gene multiplication. Discussion: We found no evidence that low amounts of sulfonamides in the aquatic environment stimulate the maintenance or even spread of corresponding ARGs. Nevertheless, class 1 integrons carrying various ARGs were still present 13 km downstream from the WWTP. Therefore, limiting the release of ARG-harboring microorganisms may be more crucial for restricting the environmental spread of antimicrobial resistance than attenuating ng/L concentrations of antibiotics. [ABSTRACT FROM AUTHOR]

This study examined the intensification of mono-sex Nile tilapia Oreochromis niloticus aquaculture in riverine net cages installed at the River Dakatia, Roghunathpur, Chandpur. This study performed 120-day cage grow-out trials with densities of 50, 75, and 100 tilapia m-3 under three replications with an average initial weight of 28.92±8.37 g per juvenile fish. The monthly water quality parameters (temperature, pH, dissolved oxygen, total alkalinity and hardness, ammonia-N and Nitrite-N) in the cage installation water area of the River Dakatia were found to be suitable for tilapia cage culture. The monthly average weight gain was significantly (p < 0.05) higher in 50 tilapia m-3 stocking density than in the other two stocking densities tested. The mean final weight and specific growth rate were significantly (p < 0.05) higher in 50 tilapia m-3 stocking density than the other two stocking densities. Significantly (p < 0.05) higher survival (97.92%) was found in the 50 tilapia m-3 stocking density group and followed by 86.74% and 84.39% in the 75 and 100 tilapia m-3 stocking densities, respectively. Consequently, the monthly relative and specific growth rate and feed conversion ratio were significantly (p < 0.05) higher in 50 tilapia m-3 stocking density fishes for the first, third, and fourth months. Gross production was comparable between 50 and 75 tilapia m-3 stocking densities but was significantly (p < 0.05) better than 100 m-3 stocking density. Net production was significantly (p < 0.05) higher at 50 tilapia m-3 stocking density group than those of 75 and 100 tilapia m-3 stocking densities. The best feed conversion ratio (1.60) was in the 50 tilapia m-3 stocking density group (p < 0.05) than those of 1.87 and 2.44 for the stocking of 75 and 100 tilapia m-3, respectively. Benefit-cost ratio and net profit were significantly (p < 0.05) better at 50 and 75 tilapia m-3 than at 100 tilapia m-3 stocking density. Therefore, considering maximum outputs, benefits, and performances, we recommend stocking density at 50 mono-sex tilapia m-3 for the best growth, cost-effective production, and highest-economic return from 120 days of grow-out net cages in the riverine culture system. [ABSTRACT FROM AUTHOR]

In 2022, Poland and Germany experienced a prolonged and extensive mass fish kill in the Odra River. During the period from the end of July to the beginning of September 2022, a high level of incidental disease and mortality was observed in various fish species (dozens of different species were found dead). The fish mortality affected five Polish provinces (Silesia, Opole, Lower Silesia, Lubuskie, and Western Pomerania) and involved reservoir systems covering most of the river (the Odra River is 854 km long, of which 742 km are in Poland). Fatal cases were investigated using toxicological, anatomopathological, and histopathological tests. Water samples were collected to determine nutrient status in the water column, phytoplankton biomass, and community composition. High nutrient concentrations indicated high phytoplankton productivity, with favorable conditions for golden algal blooms. The harmful toxins (prymnesins secreted by Prymnesium parvum habitats) had not been found in Poland before, but it was only a matter of time, especially in the Odra River, whose waters are permanently saline and still used for navigation. The observed fish mortality resulted in a 50% decrease in the fish population in the river and affected mainly cold-blooded species. Histopathological examinations of fish showed acute damage to the most perfused organs (gills, spleen, kidneys). The disruption to hematopoietic processes and damage to the gills were due to the action of hemolytic toxins (prymnesins). An evaluation of the collected hydrological, meteorological, biological, and physico-chemical data on the observed spatio-temporal course of the catastrophe, as well as the detection of three compounds from the group of B-type prymnesins in the analyzed material (the presence of prymnesins was confirmed using an analysis of the fragmentation spectrum and the accurate tandem mass spectrometry (MS/MS) measurement, in combination with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), allowed the formulation and subsequent testing of the hypothesis for a direct link between the observed fish mortality and the presence of prymnesins in the Odra River. This article systematizes what is known about the causes of the fish kill in the Odra River in 2022, based on official government reports (one Polish and one German) and the EU technical report by the Joint Research Centre. A review and critical analysis of government findings (Polish and German) on this disaster were conducted in the context of what is known to date about similar cases of mass fish kills. [ABSTRACT FROM AUTHOR]

Beta diversity represents the spatial or temporal variation of species diversity among sampling sites and may be composed of two elements: turnover (Brepl, replacement of species assemblages) and nestedness (Brich, loss or gain of species assemblages). Knowledge of the mechanisms driving beta diversity contributes to an understanding of the variation in aquatic ecosystem community structures. We sampled zooplankton assemblages at 24 sites in 11 rivers in Shanghai City and conducted a nutrient addition experiment to elucidate the effects of various environmental variables on the community structure and beta diversity patterns of the zooplankton. The zooplankton assemblages in the rivers differed significantly at ammonia nitrogen (NH3-N) concentrations below (Group I) and above (Group II) 1.03 mg·L−1. The nutrient addition experiment further demonstrated that the composition of the zooplankton assemblages changed markedly along an ammonia concentration gradient (0.2 to 5.0 mg N·L−1). The total beta diversity of Group I was considerably higher than that of Group II, indicating that high nutrient (ammonia) pollution led to biotic homogeneity. Overall, turnover was the key factor determining the total beta diversity of the two groups, suggesting the key importance of replacement of zooplankton assemblages. Furthermore, we found a correlation between environmental factors (mainly nitrogen content) and the beta diversity of zooplankton, and beta diversity (Brepl and Btotal) decreased with increasing trophic state. These findings provide further insight into the changing characteristics of the beta diversity patterns of zooplankton in river networks and may help to guide managers dealing with conservation strategies for aquatic biodiversity preservation in urban river ecosystems. [ABSTRACT FROM AUTHOR]

The Qinghai–Tibet Plateau is rich in hydropower resources for China, and the development of these has an important impact on the sustainable development of the plateau. However, the research on the pattern and processes of hydropower development on the plateau is still lacking. Using both field investigation and collected data, we evaluated the density and intensity of hydropower development on the Tibetan Plateau over the past 40 years. The spatial and temporal patterns of hydropower development were analyzed by applying exploratory spatial data analysis methods to study the spatial aggregation of hydropower development on the Qinghai–Tibet Plateau since 1980. The results show that: (1) Hydropower development on the Qinghai–Tibet Plateau can be divided into four stages—(i) pre-1980, at the beginning of development, with a small number of power stations and a small installed capacity; (ii) the period from 1980 to 2005, which was dominated by small hydropower developments, and the number of hydropower stations increased seven-fold; (iii) the 2005–2014 period, which saw large-scale cascade development; and (iv) post-2014, when hydropower development mode changed from quantity-led to scale-led. (2) Significant differences in hydropower development areas on the Qinghai–Tibet Plateau regarding the density and intensity of development from east to west are constantly decreasing. (3) The increase in hydropower development density in the past 40 years is mainly due to the increasing aggregation effect of hydropower development absorption in the eastern region (the aggregation effect of western counties has not been shown). (4) While low hydropower development intensity is found in most areas of the Qinghai–Tibet Plateau, attention must be given to river protection problems in the eastern high-intensity areas; failure to do so will increase the aggregation effect of hydropower development aggregation and, ultimately, affect the sustainable development of the regional development of the Qinghai–Tibet Plateau. [ABSTRACT FROM AUTHOR]

Dichlorodiphenyltrichloroethane (DDT) contamination in the Toce River in northern Italy was studied by collecting data from 2016 to 2021 upstream and downstream of a production factory which in the past had discharged technical DDT. Analysis of sediments and of bioaccumulation in different benthic invertebrate taxa (Gammaridae, Diptera, Ephemeroptera Baetidae and Heptageniidae) was carried out to assess the transfer of DDT from sediments to benthic invertebrates and the environmental risk of this legacy pollutant for the river ecosystem. DDT and its metabolites dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), here called DDx, were analyzed by isotope dilution gas chromatography–mass spectrometry (GC-MS/MS). DDx values in sediments in upstream stations (1.14–2.25 ng g−1 1% Organic Carbon) were lower than downstream of the industrial site (5.60–7.60 ng g−1 1% Organic Carbon), often exceeding Sediment Quality Guidelines for total DDx. Peak levels derived from new inputs of parental DDT, as confirmed by fingerprint analysis. Bioaccumulation was higher at downstream sites (up to 5107 ng g−1 lipid weight), confirming the bioavailability of residual DDT as well as active metabolism, with the formation of DDD and DDE. The Biota-Sediment Accumulation Factor evidenced the highest values (over 4.2) for Diptera and Gammaridae, highlighting that invertebrates can transfer contamination from sediments to the trophic chain. Linear regression models were developed to estimate DDx concentrations in benthic invertebrates from DDx concentrations in sediments. However, determination coefficients R2 remained in the range of 0.36–0.51, highlighting the necessity of bioaccumulation analysis to fully estimate environmental risk. The results show that DDT contamination, even if residual, may still represent a risk due to its effective transfer to the trophic chain. [ABSTRACT FROM AUTHOR]

Both gradual and extreme weather changes trigger complex ecological responses in river ecosystems. It is still unclear to what extent trend or event effects alter biodiversity and functioning in river ecosystems, adding considerable uncertainty to predictions of their future dynamics. Using a comprehensive database of 71 published studies, we show that event – but not trend – effects associated with extreme changes in water flow and temperature substantially reduce species richness. Furthermore, event effects – particularly those affecting hydrological dynamics – on biodiversity and primary productivity were twice as high as impacts due to gradual changes. The synthesis of the available evidence reveals that event effects induce regime shifts in river ecosystems, particularly affecting organisms such as invertebrates. Among extreme weather events, dryness associated with flow interruption caused the largest effects on biota and ecosystem functions in rivers. Effects on ecosystem functions (primary production, organic matter decomposition and respiration) were asymmetric, with only primary production exhibiting a negative response to extreme weather events. Our meta‐analysis highlights the disproportionate impact of event effects on river biodiversity and ecosystem functions, with implications for the long‐term conservation and management of river ecosystems. However, few studies were available from tropical areas, and our conclusions therefore remain largely limited to temperate river systems. Further efforts need to be directed to assemble evidence of extreme events on river biodiversity and functioning. [ABSTRACT FROM AUTHOR]

Bangladesh is a deltaic country in Asia, and its riverine systems ultimately drain into the Bay of Bengal. Plastic is a severe environmental issue for coastal-marine ecosystems due to the indiscriminate usage and discarding of plastic items in the upstream river that eventually find their route into the Bay of Bengal. Microplastics (MPs) are widespread pollutants in almost all environmental compartments, including aquatic environments. This study aimed to quantify and understand the distribution of microplastics in surface water and sediments of the river Karnaphuli, a tidal confluence river adjacent to the Chattogram seaport city of Bangladesh, a highly inhabited and industrial area on the southeast coast of the Bay of Bengal. A manta trawl net (300-µm mesh size) was used to collect surface water samples, while an Ekman dredge was used to collect sediment samples. The concentrations of microplastics in the surface water of the river Karnaphuli during late monsoon, winter, and early summer were recorded to be 120,111.11, 152,222.22, and 164,444.44 items/km2, respectively, while in sediments, those were recorded to be 103.83, 137.50, and 103.67 items/kg, respectively. A higher abundance of microplastics was observed in downstream surface water (228,888.88 items/km2) and sediments (164.17 items/kg). Smaller sizes (0.3 to 0.5 mm) of microplastics were predominant, fibers or threads were the frequent types, and black was the most common color in the river Karnaphuli. The Fourier transform infrared analysis revealed that polyethylene terephthalate (surface water: 22%, sediments: 19%), polyamide (surface water: 15%, sediments: 13%), polyethylene (surface water: 12%, sediments: 18%), polystyrene (surface water: 13%, sediments: 11%), and alkyd resin (surface water: 13%, sediments: 10%) were the most prevalent polymers in the river Karnaphuli. Moreover, there was a moderate positive correlation between MPs abundance in surface water and sediments. Therefore, improved long-term research (in different seasons with horizontal and vertical monitoring) is necessary in order to accurately determine the flux of microplastics from the river Karnaphuli to the Bay of Bengal. [ABSTRACT FROM AUTHOR]

Aim: We estimate and compare niche position, marginality and breadth of Iberian inland fishes at three geographical extents (regional, restricted to the species' range and global) to understand the effect of spatial scale on niche metrics. Furthermore, we investigate differences in niche metrics between native and alien fish, and test for associations with introduction date of alien species and niche characterization to better understand their invasion process. Location: Iberian Peninsula and global. Time period: 2000–2020. Major taxa studied: Fifty‐one native and 17 alien inland fish species from the Iberian Peninsula. Methods: Outlying mean index (OMI) analyses were used to estimate the niche position, marginality and breadth of Iberian inland fishes. Climatic OMI analyses were computed at three different scales (regional, restricted to the species' range and global). Permutational analyses of variance (PERMANOVAs) were used to test for differences in niche position, marginality and breath among native and alien species. Results: Niche metrics differed depending on the geographical extent of the investigation, as well as with respect to species origin (native versus alien). Differences in climatic niche position between native and alien species observed at the global scale were non‐existent at the regional scale. The niche breadth of widely distributed alien species was highly underestimated when only considering the invaded region, and further influenced by the first date of of species introduction. Main conclusions: Estimating niches of freshwater species, especially of alien invaders, should carefully consider the geographical extent of the investigation. We suggest that analyses that jointly consider regional and global scales will improve the estimation of niche metrics of widely distributed organisms, particularly regarding species climatic niche, and the assessment of the invasive potential of species. [ABSTRACT FROM AUTHOR]

Hydropeaking is known for its adverse impacts on river ecosystems. However, the implementation of mitigation measures is still largely pending due to conflicting priorities of ecology and economics, which require scenario building to assess trade‐offs. Therefore, widely applicable and standardized tools are needed to analyze hydropeaking hydrology in affected rivers to expedite mitigation efforts. Here, we present a novel empirical approach—PeakTrace—that can (a) detect and follow source‐specific hydropeaking waves in the downstream direction by using multiple hydrographs and (b) describe how to flow metrics of hydropeaking waves change along a river's course. In detail, PeakTrace first identifies associated flow events and then models translation and retention processes between neighboring hydrographs. Finally, the models can be combined to establish a non‐linear hydropower plant‐specific model. We demonstrate the PeakTrace method's usability in 16 Austrian case studies. The results underline the high performance of PeakTrace, describing the longitudinal development of flow metrics with high model accuracy up to 25 km or more. Ecologically‐relevant metrics, such as rate of change or amplitude, decrease with distance from the hydropower outlet regarding down‐ramping events; the same pattern can be observed for up‐ramping events too, except for the rate of change for which an intensity increase may be observed, probably due to slope and the roughness difference between base flow and peak flow. Overall, this paper underlines the usability of PeakTrace as a basis to assess hydropower plant‐specific hydro‐ecological impacts and evaluate hydropeaking mitigation measures, especially by incorporating critical flow thresholds of river biota and life stages. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Ritual, Theatre & Folklore / Mínsú Qǔyì is the property of Shih Ho-Cheng Folk Culture Foundation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study proposes a multipurpose cropping pattern optimization to minimize the environmental impacts of water and energy use on agriculture through the income–energy–river ecosystem nexus approach in different hydrological conditions. The following three main purposes are considered in the optimization model: (1) mitigating greenhouse gas emissions due to farming by considering minimization of agricultural energy consumption; (2) mitigating environmental impacts on the river ecosystem by considering it as the main source for supplying irrigation demand in the case study and (3) maximizing farmers’ income. Field studies are carried out in the case study for recording energy inputs to assess average energy use, irrigation demand, production yield and other required parameters for the selected crops. The fuzzy physical habitat simulation is utilized to develop an environmental impact function in the river ecosystem. Based on the results of the case study, the optimization model is able to balance energy use, impacts on the river ecosystem and farmers’ income. However, its performance is not best in terms of all the defined purposes. The results indicate that more than 50% of the initial income is provided, while energy use is mitigated by more than 70% on average. Furthermore, the river ecosystem is protected properly. HIGHLIGHTS A multipurpose cropping pattern optimization model is developed.; The environmental impacts of water and energy on agriculture are minimized simultaneously.; River habitat simulation is used for minimizing the impact of water use.; Greenhouse gas emissions are minimized.; An optimal cropping pattern is proposed.;

Vascular plants are good environmental indicators. Thus, floristic inventories have a high potential in environmental management since they reflect the current and past status of the environment. In this study, we used the flora of a suburban riverscape in central Italy to test the performance of the Floristic Quality Assessment (FQA) approach, an expert-based evaluation technique. Ten expert botanists assigned coefficients of conservatism (CC) to 382 plant species. We found statistically significant differences between the values assigned to the inventoried flora by botanical experts. In spite of this, the analysis of pseudo multivariate dissimilarity-based standard errors of CC values assigned by the different experts revealed that, in our case, an assessment by a minimum of five botanists allows characterizing the flora with a stable level of precision. We used the distance from agricultural and urban surfaces as a proxy of anthropogenic disturbance to divide the area around the river in four belts of increasing disturbance. The disturbance gradient was mirrored by median CC values and by the Adjusted Floristic Quality Assessment Index (Adjusted FQAI). Conversely, the Floristic Quality Assessment Index (FQAI), which is based on CC values and on the number of native species, showed increasing values with increasing disturbance. Comparing the performance of median CC values to Ellenberg Indicator Values (EIVs), life forms, and chorotypes, we revealed that the last three indicators may be ineffective in highlighting the conservation status of the environment. We suggest that the use of the median CC values may be a simpler and effective alternative to the calculation of indices in FQA, when the adequacy of the number of experts in minimizing the variability of CC values is a posteriori verified.

Riverine habitats are essential ecotones that bridge aquatic and terrestrial ecosystems, providing multiple ecosystem services. This study analyses the potential use of high-resolution satellite imagery, provided by the WorldView-2 satellite, in order to assess its viability for monitoring riparian ecosystems. It is performed by calculating the riparian strip quality index (RSQI) and calibrating it with the riparian quality index (QBR). The methodology was implemented in the Umia River, which is characterised by elevated anthropogenic pressures (located in the northwest of Spain). The results obtained by the method have a 92% of veracity and a kappa coefficient of 0.88. The average quality value obtained for the RSQI index was 71.57, while the average value for the QBR was 55.88. This difference could be attributed to the fact that the former does not differ between autochthonous and non-autochthonous vegetation. The areas with more accurate mapping corresponded to stretches of vegetation with optimal cover (80–50%), with good connectivity with the adjacent forest ecosystem and few or no presence of invasive plants. The worst-scoring sites had the next characteristics: low connectivity (< 10%), low forest cover (< 10%) and a higher presence of invasive plants. The degradation of vegetation could be explained by the presence of agriculture and deficient land use rationing caused by the type of ownership of the study area. The application of this index through satellite images will facilitate the environmental governance of multiple ecosystems and in special riparian ecosystems, obtaining a quick and objective methodology, easily replicable in other basins. [ABSTRACT FROM AUTHOR]

Water systems contain fine sediment as a natural phenomenon. The main cause of ecological deterioration is undesirable fine sediment. Fine sediment comprises inorganic particles of sand, silt, and clay that are less than 2 mm in diameter. Fine sediment is considered to be pollutant in water bodies (rivers, streams, lakes, and reservoirs). Sediment has various channel and nonchannel sources. Fine sediment can alter the hydraulics of rivers and their morphology. It has detrimental effects on reservoir storage and function, can degrade the food chain, and affects the reproduction of aquatic animals, which ultimately affects river ecosystems. The deposition of fine sediment renders waterways difficult to navigate and hinders recreational uses. It degrades the water quality for drinking purposes, wildlife, and affects the land surrounding the bodies of water. The intrusion of fine sediment is a global problem, and with time, researchers will understand the effects on biological and physical processes. Comprehension may help scientists minimize the effects of fine sediment on river ecosystems by considering various disciplines such as ecology, hydraulics, fluvial geomorphology, and hydrochemistry. Many researchers have investigated fine sediment in rivers. This paper reviews the literature, focusing on the consequences of intrusion on the river ecosystem, river health, and associated hydraulic parameters. The study of FSI is a major application in applied environmental science. It is applied to gain as complete an understanding of the physical and biological processes as possible. It has been applied to estimate the trap efficiency and to determine the live storage capacity of reservoirs. Excess fine sediment is a primary reason for the failure of water bodies, so it is important to control it and maintain necessary fluid properties such as viscosity, specific weight, and the optical properties of water. Proper control of fine sediment in bodies of water maintains both the survival and growth of plants, and the food chain of aquatic animals. It is important to control excess fine sediment to avoid turbidity in water. In brief, the topic has applications in various fields such as evaluating river health, live reservoir capacity, growth of flora and fauna, and water quality standards. [ABSTRACT FROM AUTHOR]

The historical Hevsel Gardens in Diyarbakır, Turkey, was registered as a UNESCO cultural heritage site in 2015. The biodiversity of the habitats was revealed by compiling the inventory obtained from the field studies in the Hevsel Gardens, and its surroundings, including the Tigris River between 2002-2021, and from the literature containing studies conducted in the region.- The results indicate that there are 607 species of flora including phytoplankton -phytobenthos and plants and 635 species of animals consisting of invertebrates (352 species), fish (27 species), amphibians (3 species), reptiles (15 species), birds (215 species) and mammals (23 species). The records revealed the following species under different threatened categories of IUCN at a global scale and The Red Book of Turkish Plants for endemic Plants: Vicia esdraelonensis (VU) and Trifolium aintabense (NT) from plants; Leguminaia wheatleyi (NT), Unio mancus (NT) from Mollusca; Oedipoda aurea (NT) from Insecta; Arabibarbus grypus (VU), Carasobarbus kosswigi (VU), Luciobarbus esocinus (VU) from Fish; Testudo graeca (VU) and Rafetus euphraticus (EN) from reptiles; Oxyura leucocephala (EN), Falco cherrug (EN), Aythya ferina (VU), Streptopelia turtur (VU), Otis tarda (VU), Falco vespertinus (VU), Pelecanus crispus (NT), Aythya nyroca (NT), Vanellus vanellus (NT), Limosa limosa (NT), and Numenius arquata (NT) from birds; Vormela peregusna (VU) and Lutra lutra (NT) from mammals. The factors threatening the area have been revealed and discussed in the paper. For the sustainable conservation of rich biodiversity, it is recommended that this region of the Tigris River and Hevsel Gardens should be protected within the scope of “Qualified Nature Protection Areas”. [ABSTRACT FROM AUTHOR]

The construction of a reservoir dam alters the environment within its basin, including composition of the fish community, fish biodiversity, and the river ecosystem itself. This study was conducted in the Sanbanxi Reservoir and used eDNA metabarcoding technology comprising eDNA capture and extraction, PCR amplification, sequencing and database comparison analysis, and other environmental DNA metabarcoding standardized analysis processes to characterize the composition and diversity of fish communities and assess their current status. A total of 48 species of fish were detected. Previously, 68 species of fish were screened and identified in this reservoir based on the reports of Dai and Gu. The results for fish community composition showed that species of the order Cypriniformes are still the most dominant in the Reservoir with 38 species of cyprinids, accounting for 90.81% of all OTUs. Carp were no longer the dominant species, and Spinibarbus denticulatus, Homalopteridae, Cobitidae, and Sisoridae were not detected, with the exception of Misgurnus anguillicaudatus (Cobitidae). These families have the common characteristic of being adapted to survive in fast-water, sandstone substrate habitats. The results also show that two of the sampling sites, sbx03 and sbx10, significantly differed from other sampling sites due to their geographical environment. The impact of the construction of reservoirs on freshwater fish communities is extreme, since the transformation from a lotic to a lentic habitat contributes to habitat destruction and constrains fish in movement. The change in the aquatic environment before and after the storage of water in the Sanbanxi Reservoir has reduced the number of fish species found in the reservoir, and species characteristically found in fast moving, rapids habitats are virtually absent. The profound change in the aquatic environment from that of a lotic to a lentic habitat leads to changes in the composition of fish populations in the reservoir and to a certain extent a reduction in the ecological stability and species diversity within the reservoir. Therefore, the protection of fish diversity in the reservoir is of great significance to the stability of the ecosystem. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The increasing consumption of medicines and the lack of efficient technologies in wastewater treatment plants (WWTPs) can release pharmaceutically active compounds (PhACs) into any given river with the subsequent risk to the environment and human health. To assess the occurrence and transfer pathways of PhACs through the river ecosystem, 22 PhACs and one metabolite were analyzed in WWTPs, river sediments and fish collected alongside the Tagus River basin between 2020 and 2022. All the matrices presented at least two drugs being azithromycin the only one quantified in all of them. Analgesics, anti-inflammatories, antihypertensives, antidepressants and beta-blockers were the main PhACs in influents, with median concentrations up to 19 μg/L. In effluents, antihypertensives and antidepressants were the PhACs with the highest contribution. For acetaminophen, ibuprofen, ketoprofen, naproxen, atorvastatin, azithromycin, clarithromycin, sulfamethoxazole, trimethoprim, and valsartan WWTPs treatments reached removal efficiencies above 75%. Compounds with a high tendency to bind to organic matter were retained in sludge (clotrimazole, 96 ng/g before digester, 100%). However, results showed that applied treatments were not effective in removing PhACs from this matrix. Although the total mass balance revealed a high removal rate of some PhACs, many of them were still present in the effluent and their release into rivers became the main source of PhAC pollution of the aquatic ecosystem. The most hydrophobic ones (irbesartan, 24 ng/g, 61%), positively charged (o-desmethylvenlafaxine, 95 ng/g, 68%) and those with affinity to organic matter (clotrimazole, 21 ng/g, 61%) reached sediment samples. Only clotrimazole (7.8 ng/g) and azithromycin (160 ng/g) were found in fish samples. Risk assessment revealed a high risk for (i) acetaminophen, clarithromycin, erythromycin A, and venlafaxine in phototrophic organisms and (ii) acetaminophen and venlafaxine in fish., Competing Interests: Declaration of Competing Interest ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)