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Numerous dams disrupt freshwater animals. The uppermost population of the critically endangered Yangtze finless porpoise has been newly formed below the Gezhouba Dam, however, information regarding the local porpoise is scarce. Passive acoustic monitoring was used to detect the behaviors of porpoises below the Gezhouba Dam. The influence of shipping, pandemic lockdown, hydrological regime, and light intensity on the biosonar activity of dolphins was also examined using Generalized linear models. Over the course of 4 years (2019–2022), approximately 848, 596, and 676 effective monitoring days were investigated at the three sites, from upstream to downstream. Observations revealed significant spatio‐temporal biosonar activity. Proportion of days that are porpoise positive were 73%, 54%, and 61%, while porpoise buzz signals accounted for 78.49%, 62.35%, and 81.30% of all porpoise biosonar at the three stations. The biosonar activity of porpoises was much higher at the confluence area, particularly at the MZ site, during the absence of boat traffic, and during the Pandemic shutdown. Temporal trends of monthly, seasonal, and yearly variation were also visible, with the highest number of porpoises biosonar detected in the summer season and in 2020. Significant correlations also exist between the hydrological regime and light intensity and porpoise activity, with much higher detections during nighttime and full moon periods. Hydropower cascade development, establishment of a natural reserve, fish release initiatives, and implementation of fishing restrictions may facilitate the proliferation of the porpoise population downstream of the Gezhouba Dam within the Yichang section of the Yangtze River. Prioritizing restoration designs that match natural flow regimes, optimize boat traffic, and reduce noise pollution is crucial for promoting the conservation of the local porpoises. [ABSTRACT FROM AUTHOR]

A new Chengyuchelys latimarginalis (Xinjiangchelyidae) specimen is reported based on a well-preserved, nearly complete shell from the upper part of the Upper Jurassic Shangshaximiao Formation of Qijiang District, Chongqing Municipality, China. The Xinjiangchelyidae were widely distributed in Asia during the Jurassic and were the dominant turtle group in Asian freshwater ecosystems during the Late Jurassic. The Qijiang specimen adds a new element to the yet poorly known freshwater vertebrate fauna and extends the geographical distribution of C. latimarginalis. This paper discusses the intraspecific variation in C. latimarginalis for the first time. It provides a new insight for studying the evolution, habitat, and diversity of xinjiangchelyids. [ABSTRACT FROM AUTHOR]

The diverse freshwater fish fauna of the Japanese archipelago is distributed among four main island landmasses, which include Hokkaido in the north, with many diadromous species. One relatively well-preserved river drainage along the southern coast of Central Hokkaido is the Mukawa River. Fish fauna surveys in the Mukawa River were mostly in downstream areas and the fish diversity is not well-documented among the upper, lower river, and coastal environments. Fish communities in the river, estuary, and sea were sampled using eDNA analysis to evaluate upstream and downstream species detections, and tidal and spatial detection variation near the river mouth. The number of species was higher at the river mouth and nearshore sites compared to the river and offshore. Fish detections reflected life history categories (freshwater resident, diadromous, brackish, or marine) and the environments. Similarity analysis showed that fish species compositions were divided into (1) upstream and midstream, (2) downstream and river mouth, (3) adjacent shore, and (4) offshore. Salmonid, cyprinid, loach, and sculpin species were detected in the river, compared to a mixture of species downstream and along the coast. This rapid assessment type study demonstrated that eDNA survey methodology would be effective for multiple river comparative surveys, seasonality studies, or evaluating possible effects of cross-river weirs or dams. [ABSTRACT FROM AUTHOR]

Up to the present, no terrestrial vertebrate fauna has been published from the pre-Pannonian Miocene of SW Hungary. In 2022 a microvertebrate assemblage was unearthed from a lime mud bed of the Middle Miocene Hidas Formation, in an abandoned coal mining field close to Hidas in the Mecsek Mts. The herpetofauna and the rodent material are described here. Fossil findings point to the Late Badenian MN 7+8 Zone, which, together with the earlier results based on the marine mollusc fauna, narrows the age of the unit to ~13.5-13.3 Ma. The amphibians and reptiles are aquatic, semiaquatic or periaquatic forms. Sedimentary features and the accompanying freshwater gastropod fauna are indicative of a shallow pond or a paludal depositional environment. Crocodylian finds reported earlier from the Hidas Formation indicate a subtropical climate, just before the end of the Miocene warm period in Central Europe. Among the rodents, glirids and flying squirrels as well as Democricetodon and Megacricetodon indicate the presence of humid arboreal vegetation around the site. The rodent taxa are well known from the Middle Miocene faunas of northern Hungary, western Romania and from the Upper Freshwater Molasse of southern Germany and Switzerland. The rodent material does not show characteristics of an insular fauna, e.g. gigantism or endemism. Consequently, although the coeval palaeogeography of the region has been described as an archipelago in the Central Paratethys, with the Mecsek Mts. being one of the islands, the area must have had ecological connections towards the northern and eastern parts of the Pannonian Basin, and the marine areas within the archipelago did not form a barrier against the distribution of microvertebrates. The corridor could have been located towards the NE from the Mecsek Mts., across the elevated basement blocks of central Hungary. [ABSTRACT FROM AUTHOR]

Water bodies in cities often suffer from intense eutrophication due to excessive nutrient addition. Hence, the restoration of a eutrophic water body to its original healthy state is crucial. Therefore, this research investigated the possible use of polyaluminium chloride (PAC) to restore a shallow pool in Thailand. A dosage of PAC at 30 g/m² was applied as slurry in a shallow pool in 2021. Water quality and sediment properties were monitored before, during, and after the application of PAC (four consecutive weeks). The results revealed that before the application of PAC, this shallow pool was hypereutrophic (mean total nitrogen of 0.74±0.32 and mean total phosphorus of 3.24±0.88 mg/l). Mean chlorophyll a was exceptionally high (887.45±48.33 µg/l). The predominant species were Spirulina sp. and Microcystis sp. After the application of PAC, the water quality parameters improved. The total phosphorus, chlorophyll a and turbidity were reduced significantly (p<0.05), and the transparency depth was enhanced. Furthermore, intact phytoplankton cells were shifted from cyanobacteria to green algae. Flocs were observed in the surface water and on the sediment. This method proved to be practical to use, low in operational cost, and did not affect freshwater fauna due to its low toxicity. [ABSTRACT FROM AUTHOR]

Alien fish invasions are causing devastating impacts on native freshwater fauna; thus, rigorous, non-invasive and cost-effective biomonitoring of lotic and lentic freshwaters to design and implement appropriate prevention and control measures is now a priority. In this study, we used a species-specific qPCR eDNA assay to monitor two of the most invasive fish species (Gambusia holbrooki and Pseudorasbora parva) in 15 river basins of Greece and validated these results with conventional fish sampling as well as existing field sampling data. Our monitoring provided new records of invasive species indicating basins for rigorous future monitoring and possible eradication attempts. The eDNA proved more sensitive as a detection tool (56% detection rate) compared to conventional electrofishing (50% detection rate) for G. holbrooki. In contrast, it proved less sensitive for detecting P. parva (38% accuracy) compared to electrofishing (44% accuracy), as evident by the two locations where the eDNA failed to detect the target species. Our study illustrates the potential of the eDNA method for regular, standardised monitoring of riverine habitats for invasive fish species by local managers for early detection. Finally, we discuss the application of eDNA in management interventions for identifying invasive species' hotspots for management prioritisation, for early detection of invaders and for the monitoring of eradication/control actions. [ABSTRACT FROM AUTHOR]

The Bjeshket e Nemuna/Alpet Shqiptare National Park is located in the western and southwestern part of Kosovo and features unique freshwater fauna. The aquatic invertebrate communities here are nearly unrecognised and need extensive studies. Ecological and faunistic research on benthic communities of rheocrenes in the Bjeshket e Nemuna show that the most important component of invertebrate fauna of local springs and streams are Chironomidae (non-biting midges). We present the preliminary list of crenobiontic macroinvertebrates in the mountain springs of Bjeshket e Nemuna/Alpet Shqiptare. The list includes crenobionts from the following groups: Hirudinea (2), Gastropoda (2), Hydrachnidia (2) and Insecta (13). [ABSTRACT FROM AUTHOR]

In South Africa, freshwater habitats are among the most threatened ecosystems, and freshwater fishes are the most threatened species group. Understanding patterns in freshwater fish diversity, threat, invasion, and protection status are vital for their management. However, few studies have undertaken such analyses at ecologically and politically appropriate spatial scales, largely because of limited access to comprehensive biodiversity data sets. Access to freshwater fish data for South Africa has recently improved through the advent of the Freshwater Biodiversity Information System (FBIS). We used occurrence records downloaded from the FBIS to evaluate spatial patterns in distribution, diversity, threat, invasion, and protection status of freshwater fishes in South Africa. Results show that record density varies spatially, at both primary catchment and provincial scales. The diversity of freshwater fishes also varied spatially: native species hotspots were identified at a provincial level in the Limpopo, Mpumalanga, and KwaZulu-Natal provinces; endemic species hotspots were identified in the Western Cape; and threatened species hotspots in the Western Cape, Mpumalanga, Eastern Cape, and KwaZulu-Natal. Non-native species distributions mirrored threatened species hotspots in the Western Cape, Mpumalanga, Eastern Cape, and KwaZulu-Natal. Some 47% of threatened species records fell outside of protected areas, and 38% of non-native species records fell within protected areas. Concerningly, 58% of the distribution ranges of threatened species were invaded by non-native species. [ABSTRACT FROM AUTHOR]

The lack of information on the extinction risk of most species is a fundamental challenge in prioritizing conservation strategies and bending the curve of current biodiversity decline. Machine learning methods have shown promising potential to fill this gap, but their applicability remains to be validated at different taxa (especially aquatic species) and spatial scales. We assessed the extinction risk of 1162 freshwater fish species in China that have not yet been included in the latest IUCN Red List using multiple neural network algorithms based on datasets of species occurrences, biological traits, phylogeny, and relevant environmental layers. The best deep learning models dramatically improved the assessment coverage from 29.9% (496 species) to 93.2–93.9% (1545–1557 species) of the whole fauna with an accuracy of 95.4–99.0%. By combining our prediction results with the IUCN Red List, we found that 23.8–26.5% (394–440 species) of Chinese freshwater fishes were identified as possibly threatened species, which is roughly four times the IUCN assessment. Newly assessed species and threatened species were mainly from the orders Cypriniformes (prediction added: 837–846 species; final threatened: 325–350 species), Siluriformes (113–122; 28–37) and Perciformes (74–76; 18–25). The increase in threatened species richness based on predictions was led by the upper reaches of the Pearl and Yangtze. Overall, our findings suggest that deep learning algorithms can provide robust and time-saving assessments of extinction risk for entire freshwater fish fauna on a large national scale, thereby facilitating relevant conservation prioritization. [ABSTRACT FROM AUTHOR]

Historical information is needed to describe in a robust manner long-term changes in the distribution of organisms, although it is in general scarce or contained in non-scientific sources. Gazetteers (or geographical dictionaries) constitute a potential source of historical species records, which has not been accurately explored yet. The dictionary edited by Pascual Madoz between 1845 and 1850 extensively described the geography, population and socioeconomic aspects in Spain. The dictionary included abundant information on wild animals and plants, with a special focus on socioeconomically relevant species. Here, we present a database generated by collecting and georeferencing the mentions to freshwater fauna records in the Madoz, which includes 10,750 occurrence records of 39 freshwater-associated taxa from 5,472 localities. This database has been made public and usable (following FAIR criteria) in GBIF. Most of the records correspond to fish (10,201 records, 94.9% of total; 33 taxa), followed by crayfish (418 records, 3.9% of total; one species). Annelids (one taxon), amphibians (one taxon), reptiles (one taxon) and mammals (three species) sum up to 132 records (1.2% of total). The database presented here can be used to estimate the baseline ranges of many freshwater species, which should inform present-day management for the conservation and recovery of endangered species and freshwater communities. [ABSTRACT FROM AUTHOR]

Body shape is a fundamental metric of animal diversity affecting critical behavioral and ecological dynamics and conservation status, yet previously available methods capture only a fraction of total body-shape variance. Here we use structure-from-motion (SFM) 3D photogrammetry to generate digital 3D models of adult fishes from the Lower Mississippi Basin, one of the most diverse temperate-zone freshwater faunas on Earth, and 3D geometric morphometrics to capture morphologically distinct shape variables, interpreting principal components as growth fields. The mean body shape in this fauna resembles plesiomorphic teleost fishes, and the major dimensions of body-shape disparity are similar to those of other fish faunas worldwide. Major patterns of body-shape disparity are structured by phylogeny, with nested clades occupying distinct portions of the morphospace, most of the morphospace occupied by multiple distinct clades, and one clade (Acanthomorpha) accounting for over half of the total body shape variance. In contrast to previous studies, variance in body depth (59.4%) structures overall body-shape disparity more than does length (31.1%), while width accounts for a non-trivial (9.5%) amount of the total body-shape disparity. [ABSTRACT FROM AUTHOR]

Nocardia seriolae causes chronic nocardiosis in various marine and freshwater aquatic animals; however, grouper species have rarely been investigated. This study evaluated the pathogenicity of nocardiosis following N. seriolae infection in the orange‐spotted grouper Epinephelus coioides. Nine identified genetic isolates of N. seriolae were tested in vivo using the intraperitoneal method and observed daily for 35 days. The most virulent isolate was then used to evaluate transmission through different routes (intraperitoneal IP, intramuscular IM, oral OR, and immersion IS) in the same fish model and was observed daily for 42 days. The results showed mild variation in virulence among N. seriolae isolates. AOD107132‐2 K and OT103003‐N11 strains displayed the highest and lowest risk virulence, respectively, based on the accumulation and kinetics of mortality. IM and IP administrations showed an early phase response with early mortality by 5 dpc (30%–100%), while slower kinetics of nocardiosis occurred in the OR and IS routes with slow mortality at 35 dpc (4%–8%). Histopathology revealed typical granulomas, confirming the progression of nocardiosis in the diseased fish. These results provide the basis for further studies on the virulence profile of N. seriolae in Taiwan and a well‐suited route of administration in orange‐spotted groupers for further prevention development. [ABSTRACT FROM AUTHOR]

Species conservation requires an understanding of the abiotic factors driving animal-environmental relationships, especially in dynamic ecosystems like non-perennial streams. Although crayfish are one of the most threatened groups of freshwater animals and are vulnerable to climate change and ecosystem degradation, data are limited for many species. Here, we evaluated crayfish-environment relationships for the Ozark Crayfish (Faxonius ozarkae), a species commonly found in Ozark Highland streams of Arkansas and Missouri. Our objectives were to: (1) evaluate the influence of spatial position, precipitation, and local physicochemical factors on crayfish density and biomass in isolated pools over a 3-year period and (2) assess pattern consistency between age groups (juveniles and age 1 +) and over time (annually and seasonally). We found few age-specific differences in crayfish density and biomass. When evaluating spatial differences, juvenile crayfish density and biomass were generally greater in upstream pools closer to perennial surface flow, while age 1 + density and biomass did not differ between stream segments. Crayfish density and biomass differed temporally, probably because of difference in precipitation, with density and biomass being greatest in a moderately wet year (2010) and lowest in years with above (2009) and below (2011) average precipitation for both age groups. Differences in crayfish density and biomass were mostly related to local habitat (i.e., pool volume, proportion of gravel substrates, substrate diversity) and water quality (i.e., pH, dissolved oxygen, conductivity) metrics. Our study adds to the growing understanding of species-environment relationships in lotic ecosystems, which will be necessary for furthering the conservation of aquatic species in non-perennial streams that are predicted to become more abundant and hydrologic variability. [ABSTRACT FROM AUTHOR]

Phylogeographic research is able to identify previously unrecognized units of biodiversity. The aeglid Aegla scamosa is a species that inhabits the Desaguadero basin waterbodies in southern South America. Crabs of the family Aeglidae are especially sensitive to changes in their environment since they have restricted distributions. The aims of our study were to characterize the phylogeography of A. scamosa across its distributional range in Argentina and to identify evolutionarily significant units from these phylogeographic data. We used mitochondrial DNA, nuclear intron, and microsatellite DNA markers to study the genetic diversity, population structure, and phylogeography of the species. Our results indicate that A. scamosa populations are genetically structured in the analyzed sub-basins and that the species comprises at least two independent evolutionarily units: one corresponding to the "North" clade and another coinciding with the "South" clade. We also found a presumptive discrepancy between the information provided by nuclear and mitochondrial markers, that tell different evolutionary stories. Our results highlight the importance of carrying out this kind of study in freshwater fauna, since they may be hiding different evolutionarily significant units as in the case of A. scamosa. The evolutionary complexity of this species should not be ignored in future conservation studies. [ABSTRACT FROM AUTHOR]

Wetlands are being contaminated by housing developments, effluents, industrial areas, and poor sanitation, resulting in the presence of plastic polymers and the development of biofilms on these materials, which represent an elevated risk to freshwater fauna and flora. The objective of this study was to characterize mesoplastics and microplastics, collected in the Gualí Wetland, Colombia, as well as to verify the presence of biofilms on such polymers. Nine water samples (36 L per sample) were evaluated at three points of the wetland; the size of the particles was determined by image analysis, the type of polymer through FTIR, and the presence of biofilms by microscopy. A total of 79 items/0.135 m3 were collected, 2 macroplastic items, 53 mesoplastic items, and 24 microplastic items. The presence of fragments (70%) and pellets (41%), with transparent (40%) and white (30%) being the predominant ones, was outstanding. Among the polymers, high-density polyethylene (HDPE) dominated, followed by expanded polystyrene. The results of SEM demonstrated the presence of diatoms on the surface of the plastic polymers. Furthermore, the results showed a greater amount of HDPE mesoplastics and microplastics in the shape of fragments and pellets. In addition, the presence of biofilms on these plastic particles can increase the adsorption of contaminants, negatively affecting this ecosystem. The outcome of this study can be used to identify bacteria that reside in biofilms associated with microplastics and mesoplastics. [ABSTRACT FROM AUTHOR]

The impacts of animals on the biogeochemical cycles of major bioelements like C, N, and P are well-studied across ecosystem types. However, more than 20 elements are necessary for life. The feedbacks between animals and the biogeochemical cycles of the other bioelements are an emerging research priority. We explored how much freshwater mussels (Bivalvia: Unionoida) were related to variability in ecosystem pools of 10 bioelements (Ca, Cu, Fe, K, Mn, Na, Mg, P, S and Zn) in streams containing a natural mussel density gradient in the US Interior Highlands. We studied the concentrations of these bioelements across the aquatic-terrestrial interface—in the porewater of riverine gravel bars, and the emergent macrophyte Justicia americana. Higher mussel density was associated with increased calcium in gravel bars and macrophytes. Mussel density also correlated with variability in iron and other redox-sensitive trace elements in gravel bars and macrophytes, although this relationship was mediated by sediment grain size. We found that two explanations for the patterns we observed are worthy of further research: (1) increased calcium availability in gravel bars near denser mussel aggregations may be a product of the buildup and dissolution of shells in the gravel bar, and (2) mussels may alter redox conditions, and thus elemental availability in gravel bars with fine sediments, either behaviorally or through physical structure provided by shell material. A better understanding of the physical and biogeochemical impacts of animals on a wide range of elemental cycles is thus necessary to conserve the societal value of freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Background: : Parasitic infestations are one of the most significant problems in global aquaculture. In addition to direct economic losses due to significant mortalities, parasites may have a significant negative impact on the fish's behaviour, energetic demands, trophic position, interspecific competition, growth rate, and reproductive function. Objectives: : We conducted the present study to evaluate the infection status of parasitic pathogens in freshwater sutchi catfish (Pangasianodon hypophthalmus) and silver dollar (Metynnis hypsauchen) farmed in Alborz province of Iran. Methods: : Between January and February 2021, 140 ornamental fish, including 70 sutchi catfish (P. hypophthalmus) and 70 silver dollar (M. hypsauchen), were delivered from various ornamental fish farms for parasitological analysis. Thorough macroscopic and microscopic examinations were performed to detect parasitic infections in delivered freshwater ornamental fish. Results: : A total of six parasite species, including five protozoan species (Nyctotherus piscicola, Trichodina heterodentata, Ichthyophthirius multifiliis, Protoopalina sp., and Hexamita sp.) and one monogenean species (Ancyrocephalus sp.), were identified in the examined fish. The overall prevalence of the recovered parasites was 46.43% (65/140) of the fish. Conclusions: : In the current study, several parasites, including Hexamita sp., Ancyrocephalus sp., Protoopalina sp., and N. piscicola, were identified as the first records of the sutchi catfish (P. hypophthalmus) and/or silver dollar (M. hypsauchen), and these two fish species are known as new hosts for the isolated parasites in ornamental fish farms in Iran. Assessing the parasitic fauna of ornamental fish is therefore critical for preventing parasite introduction into adjacent provinces as well as neighbouring countries and promoting fish health. [ABSTRACT FROM AUTHOR]

The general ideas regarding ecological biochemical adaptations in aquatic organisms are based on the results obtained by using a set of field and experimental methods over decades of research on members of marine and freshwater fish fauna and on their food items (mollusks, crustaceans) carried out by Science School in Ecological Biochemistry. Examples of biochemical adaptations in aquatic organisms are provided. Certain conclusions are drawn regarding the common and specific pattern of the metabolic adaptive response in the studied organisms growing and developing under normal conditions and upon changes in the environment. The results improve our understanding of the mechanisms behind ecological biochemical adaptations and their role in maintaining homeostasis in aquatic organisms. [ABSTRACT FROM AUTHOR]

The fauna of freshwater gastropods of the Arabian Peninsula, a desert land, is neither rich nor extensively studied. Only five species of the family Lymnaeidae have been recorded from this subcontinent so far. In February 2023, a few specimens of Radix rufescens (J. E. Gray, 1822) have been collected from the stream at Wadi Tiwi, NE Oman. The shell, female part of the reproductive organs, prostate, paraeputium and phalloteca are presented. Cytochrome oxidase subunit I (COI) sequences confirmed the assignment of these specimens to R. rufescens, known from Nepal, Bangladesh, and Myanmar, not from the Arabian Peninsula. Either R. rufescens is the sixth lymnaeid species inhabiting Arabia, or at least some of the records of R. natalensis (Krauss, 1848), whose shells are hardly discernible from the ones of R. rufescens, should be interpreted as misidentified R. rufescens. Thousands of years of the trade relations between Oman and India suggest accidental transportation of this snail by trade vessels. [ABSTRACT FROM AUTHOR]

At the landscape level, freshwater ecosystems are linked at various spatial and temporal scales by movements of different fauna components adapted to life in water. We review the literature on the state of landscape connectivity and related aquatic species that connect different types of freshwater habitats, focusing on linkages from streams, large rivers and standing water bodies. Based on existing evidence, it is clear that biotic linkages throughout current mosaic have important consequences for biological integrity and biodiversity. The recent developments with regard to urbanization, expansion of urban centers, infrastructure development, and hydropower plant construction in Albania are in line with global destruction and fragmentation of habitats resulting in the parceling up of landscapes that, in this very case, have been caused by human population growth and development activities. The primary aim of this article is to address the landscape connectivity in a wider northeastern part of Albania considering various protected areas. The landscape connectivity is a pillar component of connectivity conservation that has emerged as a response approach to a range of threats to biodiversity, which include habitat degradation and destruction, fragmentation and climate changes. The approach analyses of landscape connectivity were defined from a human perspective in a linkage among different protected areas, including National Park Albanian Alps, Nature Park Korrab-Koritnik, National Park ShebenikJabllanica, Pogradec Landscape Protected Areas and National Park Prespa. The basis of this analysis lies in the Network of Protected Areas (NPAs) of Albania. Cumulatively, the protected areas connectivity, aquatic ecosystem linkage and individual movements connect populations within and among landscape mosaics and contribute to national and regional diversity and resilience to disturbance. This study highlights the importance of considering both terrestrial and aquatic ecosystems connectivity in conservation planning and management. [ABSTRACT FROM AUTHOR]

In this article, we provide an updated list of freshwater fishes in Albania for each sub-basin. The distribution data and taxa-lists presented are based on a literature review up to October 2022 and intensive fieldwork conducted in the last 15 years. Distributional records of 101 fish species (deriving from 25 families) in 11 different sub-basins are reported. There are new records that include native, alien and translocated fish species. The distinctiveness of Albanian freshwater fishes is highlighted while defining a specific ichthyological region for the whole Balkan region. The freshwater fish fauna of Albania represents a special value of the national heritage, especially due to its diversity and a high degree of endemicity. This is mainly due to the complex geological and climatic conditions, and the location between the Adriatic and Ionian Seas on the west and the continental areas of the Balkans on the other side, which have allowed different colonization from outside the area and long periods of speciation. Eleven hydrographic basin units are analyzed for species composition, evolutionary patterns, and ecological features. This review brings the number of Albanian freshwater fish taxa to 101, with 20 species added from the previous 1995 inventory and several species deleted due to taxonomic changes. [ABSTRACT FROM AUTHOR]

Species distribution models are often used to predict the potential distributions of invasive species outside their native ranges and rely on the assumption of realized niche conservatism. Analyses observed that freshwater invasive species often show high degrees of niche expansion, suggesting limited reliability of species distribution models. However, observed niche shifts can arise because of both actual niche shifts, determined by biological factors, and apparent shifts, due to methodological issues. We compared metrics of niche dynamics calculated using different sets of variables to identify factors that could influence the rate of niche shifts. We collected presence‐only data for 40 freshwater invasive animal species, then measured niche shift dynamics using 14 different combinations of environmental variables. Shifts were assessed measuring niche overlap, expansion and unfilling, and testing for niche conservatism. We then built generalized linear mixed models relating niche shifts to methodological choices and biological features. Our results showed that methodological choices strongly affected all the considered niche dynamics metrics, while the effects of biological features were less prominent. Moreover, different niche dynamic measures sometimes provided contradictory assessments of niche conservatism. Niche analyses are powerful tools to predict areas at risk of invasion, but inappropriate methodological choices can lead to apparent niche shifts, questioning niche model reliability and biological interpretation. The high rate of niche expansion observed in freshwater invasive species highlights the importance of delineating objective criteria to determine the set of variables to be used in niche dynamic assessments. [ABSTRACT FROM AUTHOR]

The biotas of Taiwan and Hainan Islands are of continental origin, but the manner with which historical and ecological factors shaped these insular species is still unclear. Here, we used freshwater fish as a model to fill this gap by quantifying the phylogenetic structure of the insular faunas and disentangling the relative contribution of potential drivers. Firstly, we used clustering and ordination analyses to identify regional species pools. To test whether the insular freshwater fish faunas were phylogenetically clustered or overdispersed, we calculated the net relatedness index (NRI) and the nearest taxon index (NTI). Finally, we implemented logistic regressions to disentangle the relative importance of species attributes (i.e. maximum body length, climatic niche dissimilarity [ND], and diversification) and historical connectivity (HC) in explaining the insular faunas. Our results showed that the most possible species pools of Taiwan are Zhejiang and Fujian provinces, and those of Hainan are Guangdong and Guangxi provinces. These insular faunas showed random phylogenetic structures in terms of NRI values. According to the NTI values, however, the Taiwanese fauna displayed more phylogenetic clustering, while the Hainanese one was more overdispersed. Both the standard and phylogenetic logistic regressions identified HC and climatic ND as the 2 top explanatory variables for species assemblages on these islands. Our reconstruction of the paleo-connected drainage basins provides insight into how historical processes and ecological factors interact to shape the freshwater fish fauna of the East Asian islands. [ABSTRACT FROM AUTHOR]

This work presents currently available knowledge on alien species (AS) found in the inland waters of Morocco. The objective is to provide an updated list of alien species and identify the main introduction pathways and possible threats to native biodiversity. The dataset was built from an extensive literature search supplemented by our own research work (published or in progress). The main areas harboring xenodiversity in Moroccan freshwaters correspond to protected areas (e.g., Ramsar Site and SIBE). These areas are currently home to 41 confirmed AS belonging to different taxonomic groups. Fish are the most abundant taxonomic group with 21 species, followed by molluscs (7 species) and arthropods (7 species). The presence of 15 more species was also noticed but considered doubtful. Almost half of these AS were introduced intentionally. They correspond to restocking programs and are likely the most serious threat to native biodiversity through predation, competition, and hybridization. Commercial activities around aquarium and ornamental species appear as the second source favoring colonization by AS. Implementing protective regulations regarding the import of exotic species in Morocco appears very urgent to protect local native diversity. In addition, detecting and monitoring the expansion of AS within the colonized areas and studies improving biological and ecological knowledge seem crucial to mitigate their possible impacts on native communities and preserve Moroccan freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishes—the most species-rich continental vertebrate fauna on Earth—to track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish faunas. [ABSTRACT FROM AUTHOR]

The region between the Brazilian Shield and the Atlantic Ocean is characterized by the presence of numerous hydrographic basins isolated by mountainous terrain that flow directly into the ocean without forming wide coastal plains. However, knowledge about the diversity and distribution of freshwater fish in several coastal areas is still incipient. One of these areas is the Costa Verde Fluminense region, situated between the municipalities of Mangaratiba and Paraty in the Brazilian State of Rio de Janeiro. In order to eliminate the gap of knowledge about the freshwater fish fauna of this region, we prepared a list of the species, and dichotomous identification keys and illustrations of all species. We examined material from expeditions carried out between 1942 and 2019, deposited in the Ichthyological Collection of the Museu Nacional, Universidade Federal do Rio de Janeiro, Brazil. The material comes from 29 continental coastal rivers and four drainages on Ilha Grande island. We recognized 54 fish species belonging to 16 families and 9 orders. The order Siluriformes was the most diverse with 18 species, followed by Characiformes with 14 species, Cyprinodontiformes with 10 species, Cichliformes with four species, Gobiiformes with three species, Syngnathiformes with two species, and Gymnotiformes, Salmoniformes and Synbranchiformes with one species each. These records include two putative undescribed species and four introduced species. Phalloceros anisophallos was the most widely distributed species, recorded in 24 drainages. More than a half (52 %) of the native species occur exclusively in coastal streams, demonstrating the importance of the area for biogeographic and conservation studies. [ABSTRACT FROM AUTHOR]

Southern Thailand represents a region of unique freshwater biodiversity with many endemic taxa, including a number of freshwater mussel species (Bivalvia: Unionidae). In this study, we recognize 13 taxa in the tribes Contradentini, Rectidentini, Pseudodontini (subfamily Gonideinae), and Indochinellini (subfamily Parreysiinae) that inhabit different localities in the Songkhla Lake, Tapi River, and Tha Taphao River basins. Based on the results of morphological and phylogenetic analyses, we discovered among these mussels six taxa new to science, including one genus, three species, and two subspecies. New taxonomic names are introduced here as follows: Songkhlanaiagen. nov.; S. tamodienicagen. & sp. nov.; Sundadontina plugpomenicasp. nov.; Monodontina vondembuschiana tapienicassp. nov.; M. vondembuschiana thasaenicassp. nov. (Pseudodontini); and Trapezoideus thachiadensissp. nov. (Contradentini). These new taxa confirm the high conservation priority of the Southern Thai freshwater mussel fauna. [ABSTRACT FROM AUTHOR]

In South America, the knowledge of trematode diversity parasitizing freshwater fishes is still scarce, as less than 5% of the freshwater fish fauna has been examined for parasites. A similar situation applies to studies on digenean life cycles, which have become increasingly rare. Among the digenean families parasitizing freshwater fishes in the region, Haploporidae is considered the richest in species diversity. However, information about the developmental stages of haploporid life cycles remains fragmentary. Particularly, in Argentina, nine cercariae attributed to the family Haploporidae have been described using morphological analysis, and only two life cycles of this family have been completely elucidated. In this study a new type of cercaria, morphologically assigned to the family Haploporidae and collected from the snail Heleobia parchappii (Cochliopidae) in Los Padres shallow lake, Buenos Aires province, was identified using morphological and molecular techniques. The molecular analysis, based on 28S and ITS2 sequences, revealed that the cercariae were 100% identical to adult specimens of Saccocoelioides nanii (Haploporidae) parasitizing the fish Prochilodus lineatus (Prochilodontidae) from Los Talas, Buenos Aires province. Our results not only provide information about the life cycle of S. nanii but also show that a molecular and morphological approach can be extremely useful in identifying the developmental stages of digeneans and elucidating their life cycles. [ABSTRACT FROM AUTHOR]

The study gives for the new information for hydrofaunistic investigation of the Koprinka Reservoir. A total of 22 free-living freshwater nematode species were found for the period 2020, 2021. Nematode fauna and environmental factors were tested by statistical analyses. The species Monhystera stagnalis, Monhystera filiformis and Dorylaimus stagnalis were found in all six stations of the reservoir. [ABSTRACT FROM AUTHOR]

The Amazon Basin features a vast network of healthy, free‐flowing rivers, which provides habitat for the most biodiverse freshwater fauna of any basin globally. However, existing and future infrastructure developments, including dams, threaten its integrity by diminishing river connectivity, altering flows, or changing sediment regimes, which can impact freshwater species. In this study, we assess critical rivers that need to be maintained as freshwater connectivity corridors (FCCs) for selective freshwater species—long‐distance migratory fishes and turtles (both with migrations >500 km) and river dolphins. We define FCCs as river stretches of uninterrupted river connectivity that provide important riverine and floodplain habitat for long‐distance migratory and other species and that maintain associated ecosystem functions. We assessed more than 340,000 km of river, beginning with an assessment of the connectivity status of all rivers and then combining river status with models of occurrence of key species to map where FCCs occur and how they could be affected under a scenario of proposed dams. We identified that in 2019, 16 of 26 very long (>1000 km) rivers are free‐flowing but only 9 would remain free‐flowing if all proposed dams are built. Among long and very long rivers (>500 km), 93 are considered FCCs. Under the future scenario, one‐fifth (18) of these long and very long FCCs—those that are of critical importance for long‐distance migrants and dolphins—would lose their FCC status, including the Amazon, the Negro, Marañón, Napo, Ucayali, Preto do Igapó Açu, Beni, and Uraricoera rivers. To avoid impacts of poorly sited infrastructure, we advocate for energy and water resources planning at the basin scale that evaluates alternative development options and limits development that will impact on FCCs. The results also highlight where corridors could be designated as protected from future fragmentation. [ABSTRACT FROM AUTHOR]

According to our own and literature generalized data, 84 species from 34 genera of free-living flatworms (Plathelminthes: Catenulida, Rhabditophora) presently occur in the freshwater fauna of the Middle Volga region (the Tatarstan and Mari El republics). A taxonomic revision makes it possible to refine the nomenclature and synonymy of the all identified species and to eliminate "dubious" names (Mesostoma gonocephalum and Mesostoma viridatum). Eight species (Myostenostomum vanderlandi, Stenostomum constrictum, Stenostomum heebuktense, Macrostomum longituba, Koinocystis lacustris, Pontaralia beklemichevi, Microdalyellia tennesseensis and Phaenocora variodentata) recorded for the first time in the fauna of Russia. The morphological features of two limnotyphloplanids, Gieysztoria sp. 1 and Typhloplanidae gen. sp. 1 , fail to fit into the characteristics of the species known to the fauna of Russia. Additional factual confirmation is needed for six microturbellarian species (Stenostomum ignavum, Dalyellia scoparia, Castrada chlorea, etc.) recorded from the region more than 100 years ago. The data we obtained allow the zoogeographic structure and occurrence of free-living flatworms in the water bodies of the Middle Volga region to be characterized. [ABSTRACT FROM AUTHOR]

Mountain ranges are known for their particular level of biodiversity typically including a striking amount of endemism. This has been comparatively well studied for certain mountain ranges worldwide such as the Alps in Europe, the Himalayas in Asia, the Rocky Mountains in North America and the Andes in South America. Apparently, this is not the case for the mountains on the African continent and especially their freshwater fauna. One of Africa's largest high-elevated regions is the Ethiopian Highlands. The study of freshwater molluscs might potentially allow to provide valuable insights into the interplay of environmental variation and evolutionary change. Here, we present the first genetically based study of Afromontane sphaeriid bivalves in a worldwide phylogenetic framework which allowed us to assess and describe the recent diversity and endemism as well as the fauna's biogeographic background. Additionally, a new Ethiopian species of Sphaeriidae, Pisidium boessnecki Albrecht & Clewing sp. nov., could be discovered and is formally described here. Our study revealed a total of six sphaeriid species for the restricted study region in the Ethiopian Highlands of which the first two are most likely endemic: Pisidium boessnecki sp. nov., P. ethiopicum, P. cf. kenianum, P. cf. pirothi, P. cf. viridarium, and Pisidium sp. V. Based on the multigene phylogeny generated, we conclude that the observed diversity might have been caused by multiple independent colonization events from Africa. The zoogeographic affinities of all Ethiopian sphaeriids are related to the Afrotropics. The importance of these findings is discussed. [ABSTRACT FROM AUTHOR]

The Wallacean shortfall refers to the knowledge gap in biodiversity distributions. There is still limited knowledge for freshwater fish species despite the importance of focusing conservation efforts towards this group due to their alarming extinction risk and the increasing human pressure on freshwater ecosystems. Here, we addressed the Wallacean shortfall for freshwater fish faunas across Europe by using the completeness indicator derived from species accumulation curves to quantify the fish sampling efforts. The multiple potential drivers of completeness that were previously related to the sampling efforts for other species (i.e., population density, nature reserves, or distance to cities) were tested using a 10 × 10 km2 grid resolution, as well as environmental (e.g., climatic) factors. Our results suggested that although there was an overall spatial pattern at the European level, the completeness was highly country-dependent. Accessibility parameters explained the sampling efforts, as for other taxa. Likewise, climate factors were related to survey completeness, possibly pointing to the river conditions required for fish sampling. The survey effort map we provide can be used to optimize future sampling, aiming at filling the data gaps in undersampled regions like the eastern European countries, as well as to account for the current bias in any ecological modeling using such data, with important implications for conservation and management. [ABSTRACT FROM AUTHOR]

The introduction of non-native fish poses a major threat to aquatic fauna in freshwater ecosystems around the world, often as a consequence of increased predation pressure, which results in adverse environmental and socioeconomic effects. In this study, we present a survey of publicly available information on the occurrence of pirarucu (Arapaima spp.) throughout Brazil, with an emphasis on the status of native and non-native populations, and discuss the implications for the conservation of aquatic biodiversity and the urgent need for strict control and monitoring of pirarucu breeding programs, especially in regions where it is non-native. We believe that researchers and public policy makers/managers should collaborate in managing introductions of non-native fish, and develop regulations, scientific research, risk assessments, and environmental education with this end in mind. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) is increasingly used to noninvasively monitor aquatic animals in freshwater and coastal areas. However, the use of eDNA in the open ocean (hereafter referred to OceanDNA) is still limited because of the sparse distribution of eDNA in the open ocean. Small pelagic fish have a large biomass and are widely distributed in the open ocean. We tested the performance of two OceanDNA analysis methods—species-specific qPCR (quantitative polymerase chain reaction) and MiFish metabarcoding using universal primers—to determine the distribution of small pelagic fish in the open ocean. We focused on six small pelagic fish species (Sardinops melanostictus, Engraulis japonicus, Scomber japonicus, Scomber australasicus, Trachurus japonicus, and Cololabis saira) and selected the Kuroshio Extension area as a testbed, because distribution of the selected species is known to be influenced by the strong frontal structure. The results from OceanDNA methods were compared to those of net sampling to test for consistency. Then, we compared the detection performance in each target fish between the using of qPCR and MiFish methods. A positive correlation was evident between the qPCR and MiFish detection results. In the ranking of the species detection rates and spatial distribution estimations, comparable similarity was observed between results derived from the qPCR and MiFish methods. In contrast, the detection rate using the qPCR method was always higher than that of the MiFish method. Amplification bias on non-target DNA and low sample DNA quantity seemed to partially result in a lower detection rate for the MiFish method; the reason is still unclear. Considering the ability of MiFish to detect large numbers of species and the quantitative nature of qPCR, the combined usage of the two methods to monitor quantitative distribution of small pelagic fish species with information of fish community structures was recommended. [ABSTRACT FROM AUTHOR]

Crete with its complex geomorphological history is the island with the highest number of endemism observed in animal and plant taxa throughout the Aegean archipelago. While other groups of organisms within Crete are well‐studied, the freshwater gastropod fauna still remains poorly investigated. Bythinella and Pseudamnicola, are 2 genera of freshwater springsnails, both present on the island, inhabiting springs and other freshwater habitats. Here, we conduct a comprehensive study on the distribution of the different genetic lineages of the 2 gastropod genera in order to assess the mode of their differentiation on the island and infer the actual number of species present in the island. Towards these aims, sequence data from the mitochondrial gene were used and analyzed within a phylogenetic framework. For Bythinella, our results strongly support at least 5 delineated Bythinella spp. inhabiting Crete, which correspond to the already described species from previous studies with the addition of a new one. Bythinella analyses reveal an old time‐frame of differentiation with vicariant phenomena being more likely the main drivers shaping the present‐day distribution of the genus' genetic lineages. For Pseudamnicola, our data indicate the presence of at least 2 delineated Pseudamnicola spp. with a differentiation more consistent to an isolation‐by‐distance pattern of a relatively recent origin. Dispersion processes followed by isolation of the populations and/or recent speciation, seem to be the underlying process for the current distribution of Pseudamnicola lineages. [ABSTRACT FROM AUTHOR]

An update on the freshwater crab fauna of Borneo (Potamidae, Gecarcinucidae and Sesarmidae) is presented here based on literature and current data. A total of 106 species in 17 genera and three families of freshwater crabs in Borneo are known. Most species are endemic to the island, with some species restricted to unique habitats such as limestone caves and mountainous terrains. This current list does not reflect Borneo's true crab diversity because many remote areas have not been explored. Compared to Sarawak, the crab fauna in other regions of Borneo is relatively less studied. While there has been some progress in the taxonomic studies of Bornean freshwater crabs, there is a lack of studies on their ecology and biology. This data is crucial for prioritizing habitat protection and conservation efforts of the Bornean freshwater crabs. [ABSTRACT FROM AUTHOR]

Honorific scientific names have recently received intense scrutiny because societal values have changed. Across disciplines groundswells of support for renaming species have occurred; specifically those named after dishonorable people or with culturally inappropriate common names. Fishes have not been immune to this attention, but changes have come slowly. Now is the time for AFS to confront this controversial topic. The renaming processes can be aided by examining what other organizations have done. First, AFS should develop procedures for renaming species epithets and common names for species named after people who advocated racist and/or sexist views, used derogatory names in their writings, or did reprehensible things. Second, this process should include input from fisheries professionals who have to work with these names within the context of fisheries management, the AFS Diversity, Equity, and Inclusion Committee, and Indigenous peoples. Third, ichthyologists should change how their newly described species are named. As descriptions are written, an opportunity presents itself to name species with names of Indigenous peoples or after people that more closely represent the value sets of our society and profession. North Carolina, with its specious freshwater fish fauna, can serve as an illustrative case study of controversial fish names that warrant this discussion. [ABSTRACT FROM AUTHOR]

The worldwide used herbicide Glyphosate can interact with environmental variables, but there is limited information on the influence of environmental stressors on its toxicity. Environmental changes could modify glyphosate effects on non-target organisms, including parasites such as gordiids. The freshwater microscopic larvae of the gordiid Chordodes nobilii are sensitive to several pollutants and environmental variables, but their combined effect has not been evaluated yet. The aim of this study was to evaluate the impact of temperature, pH and exposure time on the toxicity of Glyphosate to C. nobilii larvae. A protocol was followed to evaluate the infectivity of larvae treated with factorial combinations of concentration (0 and 0.067 mg/L), exposure time (24 and 48 h), temperature (18, 23 and 28 °C), and pH (7, 8 and 9). The reference values were 23 °C, pH 8 and 48 h. The interaction effect on the infectivity of gordiid larvae was assessed post-exposure using Aedes aegyptii larvae as host. Results were evaluated using GLMM, which does not require data transformation. The modeling results revealed three highly significant triple interactions. Glyphosate toxicity varied depending on the combination of variables, with a decrease being observed after 24 h-exposure at pH 7 and 23 °C. Glyphosate and 28 °C combination led to slightly reduced infectivity compared to temperature alone. This study is the first to report the combined effects of glyphosate, temperature, pH and time on a freshwater animal. It demonstrates that a specific combination of factors determines the effect of glyphosate on a non-target organism. The potential use of C. nobilli as a bioindicator is discussed. In the context of global warming and considering that the behavioral manipulation of terrestrial hosts by gordiids can shape community structure and the energy flow through food webs, our results raise concerns about possible negative effects of climate change on host-parasite dynamics. [Display omitted] • We evaluated the effect of Glyphosate concentration–Temperature–pH–Time interaction. • We found three significant triple interactions by multifactorial analysis. • Glyphosate effect on C. nobilii infectivity depended on the combination of factors. [ABSTRACT FROM AUTHOR]

Facultative sexual organisms combine sexual and asexual reproduction within a single life cycle, often switching between reproductive modes depending on environmental conditions. These organisms frequently inhabit variable seasonal environments, where favorable periods alternate with unfavorable periods, generating temporally varying selection pressures that strongly influence life history decisions and hence population dynamics. Due to the rapidly accelerating changes in our global environment today, understanding the population dynamics and genetic changes in facultative sexual populations inhabiting seasonal environments is critical to assess and prepare for additional challenges that will affect such ecosystems. In this study, we aimed at obtaining insights into the seasonal population dynamics of the facultative sexual freshwater cnidarian Hydra oligactis through a combination of restriction site‐associated sequencing (RAD‐Seq) genotyping and the collection of phenotypic data on the reproductive strategy of field‐collected hydra strains in a standard laboratory environment. We reliably detected 42 MlGs from the 121 collected hydra strains. Most of MLGs (N = 35, 83.3%) were detected in only one season. Five MLGs (11.9%) were detected in two seasons, one (2.4%) in three seasons and one (2.4%) in all four seasons. We found no significant genetic change during the 2 years in the study population. Clone lines were detected between seasons and even years, suggesting that clonal lineages can persist for a long time in a natural population. We also found that distinct genotypes differ in sexual reproduction frequency, but these differences did not affect whether genotypes reappeared across samplings. Our study provides key insights into the biology of natural hydra populations, while also contributing to understanding the population biology of facultative sexual species inhabiting freshwater ecosystems. [ABSTRACT FROM AUTHOR]

The waters of the Dinaric Karst drain into both the Adriatic and the Black Sea basins. Precipitation is high, yet surface waters are scarce, with the exception of sinking streams. Dinaric Karst is a biodiversity hotspot, with diverse speleo- and epigean freshwater fauna. The distribution patterns of taxa in Dinaric Karst have arisen from a combination of vicariance and dispersal and their alteration over time. Within fishes, there are genera that include both species that are widespread and species with restricted ranges (e.g., Phoxinus, Telestes), and genera with only restricted distributions (e.g., Delminichthys, Phoxinellus). Some (Delminichthys, Phoxinellus and Dinaric Telestes) have a similar lifestyle, specialized for dwelling in sinking streams in karst poljes. The present study compares the distribution ranges of Phoxinus, Delminichthys, Phoxinellus and Telestes in Dinaric Karst based upon their mitochondrial genetic lineages, including dating of divergence times and reconstruction of ancestral geographic ranges. The biology of Phoxinus has played a major role in its wider distribution than the other three genera, which exhibit some limited ability to migrate underground, but which cannot disperse along main river courses due to their specific adaptation for dwelling in the sinking streams of karst poljes. [ABSTRACT FROM AUTHOR]

Globally, policies aiming for conservation of species, free‐flowing rivers, and promotion of hydroelectricity as renewable energy and as a means to decarbonize energy systems generate trade‐offs between protecting freshwater fauna and development of hydropower. Hydroelectric turbines put fish at risk of severe injury during passage. Therefore, comprehensive, reliable analyses of turbine‐induced fish mortality are pivotal to support an informed debate on the sustainability of hydropower (i.e., how much a society is willing to pay in terms of costs incurred on rivers and their biota). We compiled and examined a comprehensive, global data set of turbine fish‐mortality assessments involving >275,000 individual fish of 75 species to estimate mortality across turbine types and fish species. Average fish mortality from hydroelectric turbines was 22.3% (95% CI 17.5–26.7%) when accounting for common uncertainties related to empirical estimates (e.g., handling‐ or catch‐related effects). Mortality estimates were highly variable among and within different turbine types, study methods, and taxa. Technical configurations of hydroelectric turbines that successfully reduce fish mortality and fish‐protective hydropower operation as a global standard could balance the need for renewable energy with protection of fish biodiversity. [ABSTRACT FROM AUTHOR]

Reduced trophic resources can pose relevant constraints to the development of freshwater animals with complex life cycles. For amphibians, food deprived environments, such as high-altitude ponds and springs and groundwaters are frequently used for breeding. The aim of this study is to outline trophic conditions leading to extreme cases of delayed larval development and increased size at metamorphosis of a European widespread amphibian, the fire salamander (Salamandra salamandra). We collected 150 fire salamander larvae, split them in two groups, one with high and one with low trophic resource availability. We then observed the effects of nutritional conditions on larval development recording time to metamorphosis and average day growth. Moreover, in the field, we surveyed larvae growth and size at metamorphosis in two artificial subterranean sites with low prey availability. Trophic conditions strongly affected larval development and under low food treatment time to metamorphosis reached up to 416 days. In the subterranean environments we observed a similar pattern, with larvae requiring more than one year to attain metamorphosis but reaching unexpected large sizes. Environmental trophic conditions experienced during early stages can induce strong delay in metamorphosis of the fire salamander; this plasticity makes fire salamander larvae optimal models for comparative studies and cross-environment experiments. [ABSTRACT FROM AUTHOR]

New methods are required for biomonitoring of poorly known tropical ecosystems, but biological assessments of environmental status are limited by insufficient information on taxonomy, composition and ecology of local communities. The current work applies DNA‐based assessment to establish the impact of various types of anthropogenic disturbances on the freshwater macroinvertebrates in an understudied biodiversity hotspot in South Asia, an area that attracts increasing attention for the loss of aquatic ecosystems.We sampled 16 river systems in the Chittagong Hill Tracts region of Bangladesh and characterised habitat intactness based on a set of 14 environmental parameters associated with habitat quality and human activities. Whole‐community metabarcoding was used to investigate the distribution of hypothetical species‐level clusters (Operational Taxonomic Units, OTUs) across sites of different impacts.We found >900 DNA clusters of insects, decapods and molluscs, dominated by Diptera, which revealed significant variation (p < 0.001) in richness across sites. The presumed sensitive Ephemeroptera‐Plecoptera–Trichoptera (EPT) represented 15.6% of total OTU richness. The type and strength of anthropogenic stressors varied greatly across streams but did not affect total OTU diversity. In contrast, EPT richness decreased by ~50% in response to habitat degradation. Partial‐network analysis revealed 26 OTUs that may serve as potential indicators for either good or poor ecological status. Overall, our results document high diversity, local endemicity and pronounced responses to disturbance in these largely unexplored but threatened habitats.Synthesis and applications. The proposed methodology combines local habitat surveys across sites of various degrees of disturbance with species‐level metabarcoding, as a model for biological evaluation of water bodies in poorly known and inaccessible places across the world. Implemented here for the Indo‐Burmese hotspot, the approach will have great value for applied conservation management as a step towards building a biomonitoring system in this region where currently little is known about the taxonomy, diversity and endemicity in both intact and disturbed ecosystems. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are under multiple threats in modern times such as water extraction for human consumption, industries and agricultural activities, water contamination and habitat destruction for example. At the same time the biodiversity of these ecosystems are often poorly studied, especially in arid countries such as Iran. In this work, we study one of the ecologically important members of Iranian freshwater fauna, freshwater crab species of the genus Potamon. Here, we barcoded the different populations occurring in the country and delimited the species to allow for a better understanding of their distribution and taxonomy. In this study, we evaluated the taxonomical statues of Potamon species in Iran using genetic data. In addition, we created the first barcoding reference for Iranian freshwater crabs, which is an important resource for future environmental and conservation studies. [ABSTRACT FROM AUTHOR]

A recent study published in Genome Biology & Evolution explores the genetic mechanisms underlying aging and extended lifespans by focusing on bivalve molluscs, such as clams, mussels, oysters, and scallops. These marine and freshwater animals have a wide range of lifespans, from 1 year to over 500 years, making them ideal subjects for investigating longevity. The study identified a network of genes that evolve differently in long-lived and short-lived bivalves, many of which are associated with longevity in other animals. The findings suggest a shared molecular framework for extended longevity across diverse animal lineages. This research highlights the importance of studying long-lived nonmodel organisms to gain insights into aging and longevity. [Extracted from the article]

South America is home to more miniature fishes (<26 mm in standard length) than any other continent. Despite this diversity, the ecology of miniature fishes is poorly studied. To promote the study of miniature fish ecology, we investigated patterns in total richness, assemblage structure and environmental correlates for miniature fishes in the rio Jacundá drainage of the Lower Amazon River basin, Pará State. Based on multi-pass dip-netting of leaf litter at 20 locations distributed across two sites, we collected miniature species and used rarefaction to estimate 9 to 14 species might be present. The miniature fish assemblage at the upstream site was a nested subset of the downstream site, and water pH and canopy cover, two features known to be altered by deforestation, correlated most strongly with assemblage variation. Our work represents one of the first quantitative assessments of environmental correlates with miniature fish assemblages and highlights research topics that should be investigated further to promote conservation and preservation of the overlooked and understudied Amazonian diminutive freshwater fish fauna. [ABSTRACT FROM AUTHOR]

Ornamental fish farming is globally a key sector of aquaculture. The purpose of this study was to report on the parasitic fauna of ornamental fish from seven farms in the East Azerbaijan province in northwestern Iran. Between November 2020 and February 2021, a total of 600 freshwater ornamental fish of six species, including goldfish (Carassius auratus), angel (Pterophyllum scalare), guppy (Poecilia reticulata), dwarf gourami (Colisa lalia), swordtail (Xiphophorus helleri), and cichlid (Cichlasoma sp.) were collected for parasitological analysis. Six ciliate protozoan species (Trichodina mutabilis, Trichodina nobilis, Trichodina spp., Heteropolaria lwoffi, Ichthyophthrius multifiliis, and Chilodonella spp.), three species of monogenean trematodes (Dactylogyrus dulkeiti, Dactylogyrus spp. and Gyrodactylus spp.), two species of crustacean arthropods (Lernaea cyprinacea and Argulus japonicus), and a nematode (Capillaria spp.) were identified among the examined fish. Parasites were detected in the fish from 5 of 7 farms, with an overall parasitic prevalence in 26.33% (158/600) of the fish. Fish infection rates with protozoans, monogenean trematodes, crustacean arthropods, and nematodes were 16.83, 13.17, 4, and 0.33% respectively. The highest prevalence was found in X. helleri infected with Gyrodactylus spp. and P. scalare infested with Trichodina spp. Moreover, 9/100 and 10/100 of goldfish were infected with A. japonicus and L. cyprinacea, compared to 2/500 and 3/500, respectively, for all other species in combination, which is a statistically significant result (p < 0.01). Assessment of farmed fish parasitic fauna is important to inhibit the spread of infections, ensure fish production and improve fish health. [ABSTRACT FROM AUTHOR]

Microplastics (MP) have been an evolving global concern by dint of the escalation of plastic pollution in the aquatic environment. However, few data document MP ingestion and accumulation in freshwater fauna as compared to marine organisms. This study investigates the prevalence of MPs in the gastrointestinal tracts (GIT) of 45 individuals belonging to seven commonly found Bangladeshi freshwater fish species with different feeding types (herbivore, carnivore, and omnivore). A total of 81 MP items of varying shapes were detected in 76% of individuals investigated, with an average abundance of 1.80±1.65 items/individual. Of these, fiber was identified as the most prevalent ingested MP type (70%) followed by film (14%), line (10%), fragment (4%), and foam (2%). Black-colored MPs were the most dominant (27%) followed by white (26%), blue (24%), red (17%), and green (6%). The results demonstrated a higher number of MPs in the carnivore (1.95 items/individual) and omnivore (1.85 items/individual) fish species as compared to herbivore fish species. Among carnivores, Wallago attu registered the highest amount of ingested MP items (3.5 items/individual), while Anguilla bengalensis registered the highest amount of ingested MP items (2.14 items/individual) among the omnivores. The amount of ingested MPs was significantly correlated (P<0.05) with body size, body weight, and gut weight, while an insignificant correlation (P>0.05) was found between the number of consumed MPs and trophic fractions. The results provide valuable insights into the prevalence of MPs in freshwater fish in Bangladesh and associated bioaccumulation through trophic transfer. [ABSTRACT FROM AUTHOR]

The Mesozoic rise of the European freshwater gastropod fauna is still poorly understood. Compared to the well documented Cenozoic history, little is known about the patterns and processes underlying the early diversification preceding their extinction crisis at the K–Pg boundary. We assess what is probably a first pulse of diversification of the Cenozoic-type fauna in the Late Cretaceous along with the potential abiotic and biotic controls for shifts in species diversification. We find strong support that the increase in the speciation rate in the Santonian (~ 85 Myr ago) is linked to a global sea level rise, which caused extensive flooding of continental areas and the formation of vast brackish-water ecosystems. The following decline of the speciation rate coincides with a rise in diversity and reflects increasing interspecific competition. The peak in the speciation rate postdates the Cenomanian–Turonian Thermal Maximum, which probably limited the potential for diversification among freshwater gastropods due to ecological constraints. The peak coincides moreover with the end phase of the Cretaceous Terrestrial Revolution, which sparked the radiation of angiosperms. The expansion and diversification of flowering plants, being an important food source for freshwater gastropods today, could have formed a necessary basis for gastropod diversification. [ABSTRACT FROM AUTHOR]