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The diversity of Ostracoda in Central Serbia is relatively unknown. With the aim of exploring this diversity, and increasing the overall knowledge on their ecology, this study was carried out over a mountainous area in Central Serbia and some parts of the Vojvodina province. In total, 46 samples were collected from 36 water bodies, with several different habitat types. Ostracods were present in 22 of those water bodies, at 27 sites. A total of 17 species were recorded, six of which are new additions to the fauna of Serbia. A multivariate analysis (Canonical Correspondence Analysis) of ostracod communities and their relationship with measured environmental factors is given, with four out of five measured environmental factors showing a significant relationship with the distribution of recorded species. These were water temperature, altitude, electrical conductivity and dissolved oxygen, while pH was not significant. A cluster analysis (UPGMA) of the samples in which ostracods occurred was also performed using Jaccard distances. It grouped samples into 7 clusters, primarily defined by presence/absence of certain species. In addition, the proportion of non-cosmopolitan ostracod species was calculated for each sample, as well as for geographically grouped samples, to investigate if the percentage of non-cosmopolitan species potentially correlates with the observable state of sampling sites, mainly in terms of anthropogenic pressure and/or habitat degradation. [ABSTRACT FROM AUTHOR]

The separation of closely related terrestrial or freshwater species by vast marine barriers represents a biogeographical riddle. Such cases can provide evidence for vicariance, a process whereby ancient geological events like continental rifting divided ancestral geographical ranges. With an evolutionary history extending tens of millions of years, freshwater ecology, and distribution encompassing widely separated southern landmasses, osteoglossid bonytongue fishes are a textbook case of vicariance attributed to Mesozoic fragmentation of the Gondwanan supercontinent. Largely overlooked fossils complicate the clean narrative invoked for extant species by recording occurrences on additional continents and in marine settings. Here, we present a new total-evidence phylogenetic hypothesis for bonytongue fishes combined with quantitative models of range evolution and show that the last common ancestor of extant osteoglossids was likely marine, and that the group colonized freshwater settings at least four times when both extant and extinct lineages are considered. The correspondence between extant osteoglossid relationships and patterns of continental fragmentation therefore represents a striking example of biogeographical pseudocongruence. Contrary to arguments against vicariance hypotheses that rely only on temporal or phylogenetic evidence, these results provide direct palaeontological support for enhanced dispersal ability early in the history of a group with widely separated distributions in the modern day. [ABSTRACT FROM AUTHOR]

Chemical pollution, land cover change, and climate change have all been established as important drivers of amphibian reproductive success and phenology. However, little is known about the relative impacts of these anthropogenic stressors, nor how they may interact to alter amphibian population dynamics. Addressing this gap in our knowledge is important, as it allows us to identify and prioritise the most needed conservation actions. Here, we use long-term datasets to investigate landscape-scale drivers of variation in the reproductive success and phenology of UK Common frog (Rana temporaria) populations. Consistent with predictions, we found that increasing mean temperatures resulted in earlier initialisation of spawning, and earlier hatching, but these relationships were not consistent across all sites. Lower temperatures were also linked to increased spawn mortality. However, temperature increases were also strongly correlated with increases in urban area, arable area, and nitrate levels in the vicinity of spawning grounds. As with spawning and hatching, there was marked spatial variation in spawn mortality trends, where some sites exhibited steady increases over time in the proportion of dead or diseased spawn. These findings support previous work linking warming temperatures to shifts in timing of amphibian breeding, but also highlight the importance of assessing the effect of land use change and pollution on wild amphibian populations. These results have implications for our understanding of the response of wild amphibian populations to climate change, and the management of human-dominated landscapes for declining wildlife populations. [ABSTRACT FROM AUTHOR]

Context: Ongoing learning is essential for freshwater ecosystem management, but there is limited documentation of successful integration into management. Aims: We aimed to increase learning-related understanding required for effective adaptive management of water for the environment, in water-stressed and contested river systems. Methods: We developed a learning approach (requisite learning) for managing water for the environment, demonstrated with real-world examples from the Macquarie River and Marshes, Australia. Key results: Four co-existing, interdependent learning types enable effective management of water for the environment: (1) 'adjusting routines', (2) 'adaptive assessment', (3) 'changing practice', and (4) 'transforming governance', exemplified by using management of water for the environment for the Macquarie River and Marshes. To enable and improve requisite learning, stakeholder social learning, and flexibility in governance arrangements, must develop. Conclusions: Ongoing learning is essential for effective adaptive management. Understanding what requisite learning is and how capacity can be improved, will help achieve outcomes required of managing water for the environment. Implications: Effective management of water for the environment is essential, transparently delivering environmental outcomes and accounting for decision-making. To do this, we need to improve explicit learning understanding by nurturing learning mandates and champions, fostering social learning, increasing flexibility in governance arrangements, and institutionalising learning. We developed a learning approach for managing water for the environment, globally, as learning is essential for effective and successful management. This learning approach is exemplified using the Macquarie River and Marshes in the Murray–Darling Basin, Australia. To improve ongoing learning in managing water for the environment, we recommend institutionalising learning, increasing flexibility in governance arrangements, fostering social-learning capacity, and developing explicit learning understanding by nurturing learning mandates and champions. This article belongs to the collection Environmental Flows in Northern Murray–Darling Basin: what we know about the science and management after a decade of practice. [ABSTRACT FROM AUTHOR]

Caddisflies (Trichoptera) are among the most diverse groups of freshwater animals with more than 16 000 described species. They play a fundamental role in freshwater ecology and environmental engineering in streams, rivers and lakes. Because of this, they are frequently used as indicator organisms in biomonitoring programmes. Despite their importance, key questions concerning the evolutionary history of caddisflies, such as the timing and origin of larval case making, remain unanswered owing to the lack of a well-resolved phylogeny. Here, we estimated a phylogenetic tree using a combination of transcriptomes and targeted enrichment data for 207 species, representing 48 of 52 extant families and 174 genera. We calibrated and dated the tree with 33 carefully selected fossils. The first caddisflies originated approximately 295 million years ago in the Permian, and major suborders began to diversify in the Triassic. Furthermore, we show that portable case making evolved in three separate lineages, and shifts in diversification occurred in concert with key evolutionary innovations beyond case making. [ABSTRACT FROM AUTHOR]

It has long been recognized that presence–absence, localisation, size, number and shape of fish scales can be important taxonomic features. Although there are some notes on the relationship between scale morphology and ecological needs, in the absence of a sufficiently large and detailed database, the morphological variability of fish scales and the factors responsible for this variability have not yet been explored in detail. For this reason, a database—which contains the shape and relative size data of 193 freshwater fish taxa of 14 orders, originated from five biogeographic realms—has been built. Database analyses showed that both the scale shape and relative size are proper taxonomic indicators. They can be used to separate higher taxonomic categories (e.g., orders), and by the simultaneous analysis of shape and size scale morphology, we showed increased sensitivity for species‐level detachments. Our results suggest that while both the shape and the size of the fish scales are genetically determined, they are also useful descriptors of the niche segregation (habitat use, flow preference) of close relative species. Scale morphology is a promising additional tool to specify the environmental preferences of lesser known or close relative recent and extinct fish species. And also can be of great help in such cases when only the scales are available for taxonomic identification, for example, in the research field of archaeology and palaeontology. [ABSTRACT FROM AUTHOR]

Bacteria and archaea are foundational life forms on Earth and play crucial roles in the development of our planet's biological hierarchy. Their interactions influence various aspects of life, including eukaryotic cell biology, molecular biology, and ecological dynamics. However, the coexistence network patterns of these microorganisms within natural river ecosystems, vital for nutrient cycling and environmental health, are not well understood. To address this knowledge gap, we systematically explored the non-random coexistence patterns of planktonic bacteria and archaea in the 6000-km stretch of the Yangtze River by using high-throughput sequencing technology. By analyzing the O/R ratio, representing the divergence between observed (O%) and random (R%) co-existence incidences, and the module composition, we found a preference of both bacteria and archaea for intradomain associations over interdomain associations. Seasons notably influenced the co-existence of bacteria and archaea, and archaea played a more crucial role in spring as evidenced by their predominant presence of interphyla co-existence and more species as keystone ones. The autumn network was characterized by a higher node or edge number, greater graph density, node degree, degree centralization, and nearest neighbor degree, indicating a more complex and interconnected structure. Landforms markedly affected microbial associations, with more complex networks and more core species found in plain and non-source areas. Distance-decay analysis suggested the importance of geographical distance in shaping bacteria and archaea co-existence patterns (more pronounced in spring). Natural, nutrient, and metal factors, including water temperature, NH4+-N, Fe, Al, and Ni were identified as crucial determinants shaping the co-occurrence patterns. Overall, these findings revealed the dynamics of prokaryotic taxa coexistence patterns in response to varying environmental conditions and further contributed to a broader understanding of microbial ecology in freshwater biogeochemical cycling. [ABSTRACT FROM AUTHOR]

Plants in streams act as physical ecosystem engineers, both influencing and responding to hydrogeomorphic processes such as fine sediment retention. Instream vegetation may also influence propagule dispersal and retention, shaping plant community dynamics. These plant‐sediment interactions may result in synergistic feedback promoting hydrogeomorphic complexity and biogeomorphic succession. However, the role of aquatic plants (submerged or mostly submerged) in trapping propagules, fine sediment and organic matter in degraded lowland streams is uncertain. In this study, we sampled sediment (≤5 cm depth) from eight streams ranging in land use from rural to urban, including within patches of aquatic vegetation and unvegetated locations. We conducted a propagule bank trial to identify the abundance and diversity of propagules and analysed the particle size and organic matter composition of the samples. A total of 8,365 seedlings from 113 plant species were recorded with a range of hydrological tolerances. Aquatic plants retained 56% more propagules and 32% more species, and marginal vegetation retained 250% more propagules and 48% more species, than open channel locations (the least retentive location). Similar patterns were found for fine sediment and organic matter retention. Propagule bank communities were different across land‐use types but not sampling locations. The trapping effect of aquatic vegetation diminished as catchments became more urbanised. This study provides evidence that aquatic plants retain more propagules and species, and fine sediment and organic matter than vegetation‐free channel locations. Improving aquatic vegetation in streams may be an important early step in restoring hydrogeomorphic complexity and propagule retention, and the facilitation of biogeomorphic succession in degraded streams. Unfortunately, heavily urbanised streams with flashy flow regimes are unlikely to benefit from this function unless catchment‐scale hydrology is addressed. [ABSTRACT FROM AUTHOR]

Metacommunity theory predicts that the relative importance of regional and local processes structuring communities will change over ecological succession. Determining effects of these processes on taxonomic and evolutionary diversity in spatially structured freshwater habitats of different successional stages may greatly improve understanding of the maintenance of diversity across temporal and spatial scales. In this study, we evaluated crayfish diversity at local and regional scales in pond metacommunities undergoing secondary succession from beaver (Castor canadensis) disturbance. Following theoretical predictions from metacommunity ecology of the increasing importance of local processes over succession, we hypothesised a decline in crayfish local and β diversity over succession from stronger local structuring as the older ponds may provide less suitable habitat than streams.Crayfish species and phylogenetic diversity were evaluated in beaver pond metacommunities and reference headwater streams located in three catchment regions. DNA sequences from the mitochondrial cytochrome oxidase I gene were used to assign crayfish to species for community and phylogenetic diversity tests. Local and β diversity were contrasted across beaver ponds ranging in age from 24 to 70 years and as a function of metacommunity processes.Counter to predictions, local species diversity among streams and the successional stages of ponds categorised by age class (24–39 years; 42–57 years; 60–70 years) did not differ, but community and phylogenetic convergence occurred in the oldest pond ecosystems. Crayfish community composition differed between the youngest and oldest ponds, resulting from higher abundance in the youngest ponds and community convergence in the oldest ponds. The association between community composition and the environment was strongest in streams and decoupled with pond age. In contrast, the correlation between intraspecific haplotype composition and the environment increased over succession. Among the three metacommunities, the regional crayfish species diversity arose from a combination of the temporal and environmental drivers from beaver‐constructed ecosystems and dispersal limitation within catchments.This study represents the first investigation of the taxonomic and phylogenetic diversity response to the successional stages of beaver pond metacommunities. The detection of differential crayfish composition and haplotype sorting to pond age suggests a role for local structuring and further indicates that future studies should acknowledge succession in shaping species diversity at local and regional scales. Dispersal limitation within catchment regions probably contributes to the evolution of crayfish species diversity in metacommunities and the overall maintenance of biodiversity.The results support a transition in community and freshwater ecology from a recent emphasis on spatial processes towards the integration of temporal drivers to better identify regulators of taxonomic and phylogenetic diversity across scales. [ABSTRACT FROM AUTHOR]

Ecological processes that are behind distributions of species that inhabit isolated localities, complex disjunct distributions, remain poorly understood. Traditionally, vicariance and dispersion have been proposed as explanatory mechanisms that drive such distributions. However, to date, our understanding of the ecological processes driving evolution of ecological niches associated with disjunct distributions remains rudimentary.Here, we propose a framework to deconstruct drivers of such distribution using World's most widespread freshwater fish Galaxias maculatus as a model and integrating marine and freshwater environments where its life cycle may occur. Specifically, we assessed ecological and historical factors (Gondwanan vicariance, marine dispersion) and potential dispersion (niche‐tracking) that explain its distribution in the Southern Hemisphere.Estimated distribution was consistent with previously reported distribution and mainly driven by temperature and topography in freshwater environments and by primary productivity and nitrate in marine environments. Niche dynamics of G. maculatus provided evidence of synergy between vicariance and marine dispersion as explanatory mechanisms of its disjunct distribution, suggesting that its ecological niche was conserved since approximately 30 Ma ago.This integrated assessment of ecological niche in marine and freshwater environments serves as a generic framework that may be applied to understand processes underpinning complex distributions of diadromous species. [ABSTRACT FROM AUTHOR]

Copyright of Journal of University of Anbar for Pure Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

This explorative study was aimed at first characterizing the sponge Spongilla lacustris (Linnaeus, 1759) from the sub‐Arctic Pasvik River (Northern Fennoscandia), in terms of associated microbial communities and pollutant accumulation. Persistent organic pollutants were determined in sponge mesohyl tissues, along with the estimation of the microbial enzymatic activity rates, prokaryotic abundance and morphometric traits, and the analysis of the taxonomic bacterial diversity by next‐generation sequencing techniques. The main bacterial groups associated with S. lacustris were Alphaproteobacteria and Gammaproteobacteria, followed by Chloroflexi and Acidobacteria. The structure of the S. lacustris‐associated bacterial communities was in sharp contrast to those of the bacterioplankton, being statistically close to those found in sediments. Dieldrin was measured at higher concentrations in the sponge tissues (3.1 ± 0.4 ng/g) compared to sediment of the same site (0.04 ± 0.03 ng/g). Some taxonomic groups were possibly related to the occurrence of certain contaminants, as was the case of Patescibacteria and dieldrin. Obtained results substantially contribute to the still scarce knowledge of bacterial community diversity, activities, and ecology in freshwater sponges. Practitioner Points: Microbial community associated with Spongilla lacustris is probably shaped by the occurrence of certain contaminants, mainly dieldrin and heavy metals.A higher accumulation of dieldrin in the sponge mesohyl tissues than in sediment was determined.S. lacustris is suggested as sponge species to be used as a sentinel of pesticide pollution in the Pasvik River.S. lacustris, living in tight contact with soft substrates, harbored communities more similar to sediment than water communities. [ABSTRACT FROM AUTHOR]

The kelt phase of anadromous iteroparous salmonid life history remains mysterious, particularly aspects of their habitat use and factors influencing survival. Atlantic salmon and sea‐run brown trout were captured in the estuary during their return migration to the Vosso River, Norway, tagged with acoustic transmitters, and tracked in the watershed and estuary in three different years (2020–2023). We found a relatively narrow window of river exit timing among trout that survived overwinter, whereas salmon tended to leave during a more protracted period. Trout preferred overwintering in lakes within the river system, which provided for lower locomotor activity than fish that overwintered in pools in the river according to data from tri‐axial accelerometer transmitters. In contrast, Atlantic salmon tended to spend surprisingly little time in lakes even though the energy expenditure in this habitat is was seemingly lower for salmon that did overwinter in the lake. Our results demonstrate different use of habitat during overwintering and could suggest that measures to protect iteroparous life history strategies of salmonids will differently impact these two iteroparous salmonids. [ABSTRACT FROM AUTHOR]

Climate change and land‐use change are widely altering freshwater ecosystem functioning and there is an urgent need to understand how these broad stressor categories may interact in future. While much research has focused on mean temperature increases, climate change also involves increasing variability of both water temperature and flow regimes and increasing concentrations of atmospheric CO2, all with potential to alter stream invertebrate communities. Deposited fine sediment is a pervasive land‐use stressor with widespread impacts on stream invertebrates. Sedimentation may be managed at the catchment scale; thus, uncovering interactions with these three key climate stressors may assist mitigation of future threats. This is the first experiment to investigate the individual and combined effects of enriched CO2, heatwaves, flow velocity variability, and fine sediment on realistic stream invertebrate communities. Using 128 mesocosms simulating small stony‐bottomed streams in a 7‐week experiment, we manipulated dissolved CO2 (ambient; enriched), fine sediment (no sediment; 300 g dry sediment), temperature (ambient; two 7‐day heatwaves), and flow velocity (constant; variable). All treatments changed community composition. CO2 enrichment reduced abundances of Orthocladiinae and Chironominae and increased Copepoda abundance. Variable flow velocity had only positive effects on invertebrate abundances (7 of 13 common taxa and total abundance), in contrast to previous experiments showing negative impacts of reduced velocity. CO2 was implicated in most stressor interactions found, with CO2 × sediment interactions being most common. Communities forming under enriched CO2 conditions in sediment‐impacted mesocosms had ~20% fewer total invertebrates than those with either treatment alone. Copepoda abundances doubled in CO2‐enriched mesocosms without sediment, whereas no CO2 effect occurred in mesocosms with sediment. Our findings provide new insights into potential future impacts of climate change and land use in running freshwaters, in particular highlighting the potential for elevated CO2 to interact with fine sediment deposition in unpredictable ways. [ABSTRACT FROM AUTHOR]

Climate change and sea-level rise cause seawater intrusion into freshwater ecosystems, risking increased salinity exposure for freshwater fish, endangering their long-term sustenance. To understand the effects of environmentally realistic increase in salinity exposure on freshwater fish, a total of 120 banded gourami, Trichogaster fasciata ( 8.54 g average initial weight) were exposed to four different salinities (0, 3, 6, and 9‰) for 90 days. The weight gain and specific growth rate values were significantly higher in the fish exposed to 3‰ compared to 0‰, and the lowest feed conversion ratio and survival rate were recorded in 3‰ and 9‰, respectively. The blood glucose and hemoglobin contents were found to be significantly higher and lower at 9‰ after 30 and 60 days, respectively, relative to 0‰. Moreover, significant low red blood cell counts were found at 6 and 9‰ after 30 and 90 days, respectively. Whereas, the white blood cell counts showed an opposite trend. Abnormalities of erythrocyte shape were significantly higher at 9‰, compared to 0‰. Results suggest that long-term exposure to high salinity (6, and 9‰) would cause osmotic stress and impair the physiological performance of freshwater gourami. [ABSTRACT FROM AUTHOR]

Long‐term biodiversity monitoring is crucial for freshwater ecosystems as it enables the detection of even subtle changes and biodiversity trends, guiding conservation efforts and ensuring the sustainability of these vital habitats. Despite becoming more commonly considered in the field of freshwater ecology and biological invasions, studies using long‐term time series from Türkiye's freshwater resources have remained scarce.To assess the availability of data and ultimately present a baseline for future efforts, we combined published museum records and samples from recent field studies from the highly anthropogenically‐altered Lake Bafa in Western Anatolia covering the period 1958–2019.Lake Bafa has a very diverse aquatic ecosystem, providing habitat for both freshwater and saltwater species, and is one of the allottees in Türkiye's inland fish production. In the current study, we investigated how fish populations in Lake Bafa were affected by environmental changes and examined changes in taxonomic and functional diversity of non‐native species over time.The analyses revealed—concomitant to an increase in native marine and freshwater species richness—an increase in non‐native species richness over time. Non‐native species did not interfere with native species' niche space, whereas applied models indicate that in this highly altered ecosystem, foremost temperature and salinity shaped the fish community over time, limiting the impacts of non‐native species.These results have implications for the fishery of the lake, which includes highly valuable catadromous fish species, highlighting the value and importance of collecting long‐term data in Türkiye to better understand both invasion dynamics and changes in the naturality of Turkish ecosystems. These findings further underline the importance of long‐term data to create new management strategies for the lake and to start restoration processes, thus improving fisheries management. [ABSTRACT FROM AUTHOR]

Prior research on metacommunities has largely focused on snapshot surveys, often overlooking temporal dynamics. In this study, our aim was to compare the insights obtained from metacommunity analyses based on a spatial approach repeated over time, with a spatio-temporal approach that consolidates all data into a single model. We empirically assessed the influence of temporal variation in the environment and spatial connectivity on the structure of metacommunities in tropical and Mediterranean temporary ponds. Employing a standardized methodology across both regions, we surveyed multiple freshwater taxa in three time periods within the same hydrological year from multiple temporary ponds in each region. To evaluate how environmental, spatial and temporal influences vary between the two approaches, we used nonlinear variation partitioning analyses based on generalized additive models. Overall, this study underscores the importance of adopting spatio-temporal analytics to better understand the processes shaping metacommunities. While the spatial approach suggested that environmental factors had a greater influence, our spatio-temporal analysis revealed that spatial connectivity was the primary driver influencing metacommunity structure in both regions. Temporal effects were equally important as environmental effects, suggesting a significant role of ecological succession in metacommunity structure. [ABSTRACT FROM AUTHOR]

This is the first report on microbial communities associated with the freshwater snail Kamtschaticana kamtschatica inhabiting diverse types of water bodies in Eastern Siberia and the Russian Far East. Using metabarcoding data based on 16S rRNA gene fragments, taxonomic profiling of bacterial communities associated with snails from three water bodies of the Magadan Oblast was carried out. Predominant phyla in the studied bacterial communities were Pseudomonadota, Bacillota, Cyanobacteriota, Actinomycetota, Verrucomicrobiota, Planctomycetota, and Bacteroidota. The highest alpha-diversity, according to the Chao1 index, was revealed in the mollusks from the Orotukan Reservoir. The relative abundance of bacteria of the genera Snowella, Leptolyngbya, Nodosilinea, Arenimonas, and Polaromonas significantly distinguished the mollusks of this habitat from mollusks of the other two water bodies. The greatest similarities in the composition of the microbiota in K. kamtschatica were found for the genus Pseudomonas, which was present in the majority of samples in the amount of more than 1% and was not found in the sediment samples. Obtained data on the diversity and composition of bacterial communities associated with lymnaeid snails are of fundamental importance for the ecology of freshwater mollusks. [ABSTRACT FROM AUTHOR]

Trait‐based approaches have received increasing interest among freshwater scientists given their capacity to predict community structure and biodiversity effects on ecosystem functioning. However, the inconsistent development and use of trait concepts and terms across freshwater scientific disciplines may have limited realisation of the potential of traits.Here, we reviewed trait definitions and terms use to provide recommendations for their consistent application in freshwater science. To do so, we first reviewed literature to identify established trait definitions, historical and current use of trait terms and challenges restricting the application of trait‐based approaches in freshwater science. Next, we surveyed 414 freshwater researchers from 54 countries to assess variability in the current use of trait terminology in relation to respondent characteristics (i.e., professional experience, geographical region, research discipline, and focal freshwater ecosystem, biotic group, and ecosystem function).Our literature review identified two well‐established trait definitions, which emphasise individual phenotypic characteristics that influence either eco‐evolutionary aspects (i.e., organism performance and fitness) or ecosystem dynamics and processes (i.e., responses to the environment and/or effects on ecosystem functioning). Publications used a range of trait‐related terms and their frequency of use varied among scientific fields. The term functional trait dominated fields such as biodiversity conservation, environmental sciences and ecology, plant sciences and microbiology. In contrast, the terms biological trait, functional trait, and species trait were used with similar frequencies in fields such as entomology, fisheries, marine and freshwater biology, and zoology. We also found that well‐established trait definitions are difficult to apply to freshwater unicellular organisms, colonial multicellular organisms, genomic information, and cultural traits.Our survey revealed highly inconsistent use of trait terms among freshwater researchers. Terms including biological trait, functional trait, structural measure, and ecosystem function were commonly used to describe the same traits or functions. Variability in the use of terms was generally explained by research discipline, geographical region, and focal biotic group and ecosystem functions.We propose making the trait concept flexible enough to be applicable to all freshwater biota and their characteristics, while keeping and integrating links to eco‐evolutionary and ecosystem aspects. Specifically, our new definition expands the established functional trait definition by considering also supra‐individual scales of trait measurement (colonial‐ or community‐mean traits), genotypic traits (e.g., functional gene markers of enzymes) and cultural traits (e.g., feeding behaviours, communication skills). To reduce terminological ambiguity, we also recommend that researchers define trait terms, prioritising the use of functional trait as an overarching term over alternative terms (e.g., biological trait), and restricting specific terms (e.g., morphological trait) to situations in which such precision is desirable. The findings of our integrative study could help to improve terminological consistency across freshwater disciplines and to better recognise the potential of traits to elucidate the mechanisms behind ecological patterns. [ABSTRACT FROM AUTHOR]

The trophic ecology of fishes in the genus Rhamdia remains poorly reported. Here, we aim to describe the diet composition and infer the trophic levels, niche breadth, and niche overlap between Rhamdia guatemalensis and Rhamdia laticauda in northeast Oaxaca, Mexico. Fishes were sampled using an electrofishing device between 2016 and 2017. We calculated the Quotient index and the diet composition was analyzed using the percentage of the Index of Relative Importance (%IRI) to analyze possible ontogenetic and sexual differences on feeding ecology. We then calculated the trophic niche breadth using the Levins´ standardized index (BA). Trophic levels (TLk) of each species were calculated using the trophic index and trophic niche overlap using Pianka´s index (Ojk). The results indicate that both species are carnivorous and tend to prey on aquatic insects, with R. guatemalensis feeding on nine different orders of animals and R. laticauda displaying a broader diet spectrum, encompassing 19 orders. Our data showed ontogeny and sex differences in the trophic ecology of R. guatemalensis. They were secondary consumers (TLk > 3) and showed a specialized diet (BA < 0.4). We found evidence of trophic niche partitioning between adults (Ojk = 0.40) and females (Ojk = 0.42). Our results highlight the fundamental role of this species in the area as a carnivorous/insectivorous, predatory fishes, secondary consumers, and biological control for Diptera, Ephemeroptera, and Megaloptera. Both species minimize the trophic overlap through food resource partitioning mediated by fish body size. Additionally, adults and females consume different prey, which allows the coexistence of closely related species. Our findings regarding trophic ecology could be crucial for devising conservation and management plans for these particular Rhamdia species. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the L.N. Gumilyov Eurasian National University. Bioscience Series is the property of L.N. Gumilyov Eurasian National University 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 Mediterranean region stands as a prominent biodiversity hotspot for the full spectrum of its habitats. However, it ranks among the most extensively invaded regions globally. This characterization aptly applies to the Balkan Peninsula, an expanse renowned for its elevated levels of biodiversity and endemism concerning freshwater fishes. Among the most frequently introduced fauna in the Balkans is the rainbow trout Oncorhynchus mykiss (Walbaum, 1792). Among the regions with very limited information available concerning the species' distribution in Greece is Mount Olympus. The current study reports the first record of several Oncorhynchus individuals from upstream of Enipeas River. The specimens in view are the first ichthyofauna record for the region. Also, this manuscript discusses the potential introduction vectors. Two different methodologies were used. The first was the use of citizen-science and the second was the use of underwater cameras and systematic surveys at Enipeas River. The estimated depth at sampling stations ranged from 0.5 to 2 m. Trout individuals were found in all sampling stations, estimated at 7–10 cm in length. [ABSTRACT FROM AUTHOR]

Habitat assessment is the most important step in environmental decisions. One of the ways to assess habitat quality is to use habitat suitability for fish species. So, this study was conducted in Klarood River, one of the important tributaries of Babolrood River in Mazandaran Province, north of Iran to evaluate the habitat quality for Capoeta razii. At first, a site with the least anthropogenic influences was selected on the river. Then the fish was caught by electrofishing device aggregate at 100 points. At each point where the fish was caught, environmental parameters such as depth, water velocity, type of biotic and abiotic substrate were also measured. The results showed that the species prefers water velocity of 16-30 cm s-1 and depth of 16-115 cm. Moreover, suitable abiotic and biotic substrates were Macrolithal, Mesolithal and Microlithal" as well as LPTP (Live parts of terrestrial plants) respectively. Generally, the results of this study showed the appropriate function of the model in assessing the habitat suitability of this species and it can be used as a guide for quantitative assessment of habitat as well as recognizing the behavioral characteristics of the studied species. [ABSTRACT FROM AUTHOR]

Chemical pollution, land cover change, and climate change have all been established as important drivers of amphibian reproductive success and phenology. However, little is known about the relative impacts of these anthropogenic stressors, nor how they may interact to alter amphibian population dynamics. Addressing this gap in our knowledge is important, as it allows us to identify and prioritise the most needed conservation actions. Here, we use long-term datasets to investigate landscape-scale drivers of variation in the reproductive success and phenology of UK Common frog (Rana temporaria) populations. Consistent with predictions, we found that increasing mean temperatures resulted in earlier initialisation of spawning, and earlier hatching, but these relationships were not consistent across all sites. Lower temperatures were also linked to increased spawn mortality. However, temperature increases were also strongly correlated with increases in urban area, arable area, and nitrate levels in the vicinity of spawning grounds. As with spawning and hatching, there was marked spatial variation in spawn mortality trends, where some sites exhibited steady increases over time in the proportion of dead or diseased spawn. These findings support previous work linking warming temperatures to shifts in timing of amphibian breeding, but also highlight the importance of assessing the effect of land use change and pollution on wild amphibian populations. These results have implications for our understanding of the response of wild amphibian populations to climate change, and the management of human-dominated landscapes for declining wildlife populations.

Freshwater biodiversity faces a critical situation globally. Current efforts to protect and conserve India's freshwater biodiversity have been insufficient in light of emerging challenges. To address this, we propose 14 science-based and policy-backed recommendations aimed at achieving long-term protection of Indian freshwater ecosystems and biodiversity conservation goals. Managers of India's nodal agencies have expressed support for implementing these recommendations. The Wildlife Institute of India has recently launched a pioneering master's degree programme in freshwater ecology and instituted scholarships for local citizens known as 'Guardians of the Ganga', who are actively engaged in conserving biodiversity along the Ganga River under the auspices of the 'Biodiversity Conservation and Ganga Rejuvenation' project sponsored by the National Mission for Clean Ganga. These initiatives align closely with our proposed recommendations. Implementing these timely recommendations by policymakers is crucial to safeguarding India's freshwater biodiversity. [ABSTRACT FROM AUTHOR]

Zhu et al. (Science 380:1230, 2023, https://doi.org/10.1126/science.adi6022) recently reported in Science that 'water diversions' carry a range of freshwater invasive non-native species (INNS) in China, and make calls for the Chinese government to take actions to monitor this invasion pathway and prevent future spread. This issue is not confined to China however. Water diversions, more commonly known internationally as 'water transfers' or 'raw water transfers', exist globally in large numbers. Despite worldwide occurrence, this major invasion pathway has received little attention within the field of freshwater ecology or invasion ecology, beyond a limited number of regional studies which offer little context regarding the global nature of the pathway. We discuss the factors contributing to the widespread lack of awareness of this uniquely complex invasion pathway, and emphasise the importance of future collaboration and knowledge sharing in this emerging field. Transdisciplinary research is needed to develop effective management techniques for this invasion pathway and ensure that the threat to global freshwater biodiversity posed by INNS is dealt with comprehensively. [ABSTRACT FROM AUTHOR]

Global warming threatens freshwater ecosystems and compromises fish survival. To elucidate the role of miRNAs in the livers of heat stressed largemouth bass, juvenile fish was subject to heat stress under 37 °C. Both mRNA-seq and miRNA-seq were conducted on the liver tissues under control and heat stress conditions. Differential gene expression analysis and enrichment analysis were performed on mRNA and miRNA expression profiles. A total of 406 differentially expressed genes (DEGs) were discovered, of which 212 were up-regulated and 194 were down-regulated. Most of the DEGs were significantly implicated in the regulation of "protein processing in endoplasmic reticulum", "proteasome", "steroid biosynthesis", and "ornithine decarboxylase inhibitor activity" pathways. In addition, 47 differentially expressed miRNAs (DEMs) were identified in largemouth bass livers under heat stress, including 21 up-regulated and 25 down-regulated miRNAs. A negatively regulated miRNA-mRNA network including 12 miRNAs and 19 mRNAs was constructed with DEMs involved in "protein degradation", "calcium ion regulation", "cell apoptosis", and "lipid metabolism". Moreover, this study indicated novel-miR-144 activated the IRE1 signaling pathway by targeting txndc5 to induce liver apoptosis in largemouth bass under heat stress. This study revealed the involvement of miRNA regulation in largemouth bass in response to heat stress. [ABSTRACT FROM AUTHOR]

'Biodiversity offsetting' aims to address the residual negative environmental impacts of human development. It's goal is to achieve No Net Loss (NNL), and preferably a Net Gain of biodiversity attributes between development and offset sites. Biodiversity offsetting suffers from a lack of 'proof of concept', as little work has been done to critically test the ecological efficacy of offsetting practices. Offsetting of stream ecological functions was investigated in Aotearoa New Zealand, via review of regulatory documentation for 76 offsets and field assessments of 14 offset sites. Field results indicated some functions, including fish passage connectivity, respond rapidly post-offset enhancement whilst others exhibit recovery lags (such as fish spawning habitat provision). However, most offsets were considered unlikely to achieve NNL due to failures in practice and process. Factors included inadequate consideration for restoration uncertainty, inappropriate monitoring conditions, insufficient data and inequivalent trade-offs. Key linkages between aquatic and terrestrial ecosystems, particularly regarding floodplain connectivity, were poorly considered in offset implementation. Thus, development may be occurring based on inadequate regulatory processes, and poorly evaluated ecological outcomes. These findings join a growing body of evidence which indicates that, in the context of a global biodiversity crisis, offsetting is not achieving its purpose of NNL. [ABSTRACT FROM AUTHOR]

Assessing the sensitivity of freshwater species to climate change is an essential component of prioritizing conservation efforts for threatened freshwater ecosystems and organisms. Sensitivity to climate change can be systematically evaluated for multiple species using geographic attributes such as range size and climate niche breadth, and using species traits associated with climate change sensitivity. These systematic evaluations produce relative rankings of species sensitivity to aid conservation prioritization and to identify relatively sensitive species that may otherwise be understudied or overlooked. Due in part to biogeographic constraints, species assemblages change across regions and spatial extents; yet, the degree to which spatial factors influence relative rankings of species sensitivity is unclear. The spatial extent of multispecies analyses may alter relative rankings of species climate sensitivity; alternatively, relative climate sensitivity may be conserved among spatial scales, resulting in consistent identification of sensitive species among regions and spatial extents. We investigated how spatial extent influences our understanding of relative climate sensitivity for 137 native freshwater fishes of the United States that were representative of taxonomic, trait, and geographic diversity. Using publicly available occurrence data from the Global Biodiversity Information Facility, we calculated a systematic, geographically derived index of climate change sensitivity for study species at national and regional extents, including within four major hydrologic subregions of the United States. We examined the effects of spatial extent on the relative ranking of climate sensitivity among species, and we explored relationships among climate sensitivity, species traits, and conservation status at regional and national extents. We found that climate sensitivity rankings of species were influenced by spatial extent in some specific instances, but that relative rankings were largely conserved across spatial scales. However, correlations among geographically derived climate sensitivity rankings and species traits associated with climate sensitivity were variable across scales and regions, suggesting that links between geographic rarity and species traits may be scale‐dependent in some cases. Finally, we found few associations between climate sensitivity and current conservation status among species. Systematic approaches to quantifying climate sensitivity may offer an opportunity to identify sensitive but overlooked species for pre‐listing actions such as monitoring or conservation agreements. [ABSTRACT FROM AUTHOR]

Herbivory can hinder restoration success by limiting the recovery of plant biodiversity. This study investigates whether plant-plant interactions, such as associational defenses, can increase the survival of a palatable species in restoration contexts where herbivory inhibits recovery. Specifically, we investigate the potential of associational defenses by the perennial Nuphar advena (yellow pond-lily) to influence the growth and survival of Zizania aquatica (annual wild rice) in a freshwater tidal marsh restoration where goose herbivory has limited Z. aquatica recovery. Wild rice was planted within exclosures and unfenced control plots located within patches of N. advena or adjacent mudflat. In an additional treatment to test the negative effects of light competition, we planted Z. aquatica in exclosures located within experimental clearings in N. advena patches. We also surveyed grazing pressure on naturally-occurring Z. aquatica within transects that spanned N. advena patches and adjacent mudflat. Based on observational and experimental results, N. advena provided clear protection from grazing for Z. aquatica. However, there was a cost to Z. aquatica growing in N. advena patches– plantings within N. advena had greater mortality and significantly reduced biomass due to low light availability. [ABSTRACT FROM AUTHOR]

Wildlife is increasingly exposed to sublethal transient cancer risk factors, including mutagenic substances, which activates their anti-cancer defences, promotes tumourigenesis, and may negatively impact populations. Little is known about how exposure to cancer risk factors impacts the behaviour of wildlife. Here, we investigated the effects of a sublethal, short-term exposure to a carcinogen at environmentally relevant concentrations on the activity patterns of wild Girardia tigrina planaria during a two-phase experiment, consisting of a 7-day exposure to cadmium period followed by a 7-day recovery period. To comprehensively explore the effects of the exposure on activity patterns, we employed the double hierarchical generalized linear model framework which explicitly models residual intraindividual variability in addition to the mean and variance of the population. We found that exposed planaria were less active compared to unexposed individuals and were able to recover to pre-exposure activity levels albeit with a reduced variance in activity at the start of the recovery phase. Planaria showing high activity levels were less predictable with larger daily activity variations and higher residual variance. Thus, the shift in behavioural variability induced by an exposure to a cancer risk factor can be quantified using advanced tools from the field of behavioural ecology. This is required to understand how tumourous processes affect the ecology of species. [ABSTRACT FROM AUTHOR]

Our aim was to examine temporal change in alpha and beta diversity of freshwater fish communities in rivers that have urbanized over the same period to understand the influence of changes in land use and river connectivity on community change. We used biological (2001–2018), land use (2000–2015), and connectivity data (1987–2017) from Toronto, Ontario, Canada. We used linear mixed effects models to determine the strength of upstream land use, connectivity, and their changes over time to explain temporal change in alpha and beta diversity indices. We examined beta diversity using the temporal beta diversity index (TBI) to assess site‐specific community change. The TBI was partitioned into gains and losses, and species‐specific changes in abundance were assessed using paired t‐tests. There were more gains than losses across the study sites as measured by TBI. We found little to no significant differences in species‐specific abundances at aggregated spatial scales (study region, watershed, stream order). We found different relationships between landscape and connectivity variables with the biodiversity indices tested; however, almost all estimated confidence intervals overlapped with zero and had low goodness‐of‐fit. More fish biodiversity gains than losses were found across the study region, as measured by TBI. We found TBI to be a useful indicator of change as it identifies key sites to further investigate. We found two high value TBI sites gained non‐native species, and one site shifted from a cool‐water to warm‐water species dominated community, both of which have management implications. Upstream catchment land use and connectivity had poor explanatory power for change in the measured biodiversity indices. Ultimately, such spatial–temporal datasets are invaluable and can reveal trends in biodiversity useful for environmental management when considering competing interests involved with urban sprawl in the ongoing "Decade on Restoration." [ABSTRACT FROM AUTHOR]

Cyanobacterial harmful algal proliferations (cyanoHAPs) are increasingly associated with dog and livestock deaths when benthic mats break free of their substrate and float to the surface. Fatalities have been linked to neurotoxicosis from anatoxins, potent alkaloids produced by certain genera of filamentous cyanobacteria. After numerous reports of dog illnesses and deaths at a popular recreation site on Lady Bird Lake, Austin, Texas in late summer 2019, water and floating mat samples were collected from several sites along the reservoir. Water quality parameters were measured and mat samples were maintained for algal isolation and DNA identification. Samples were also analyzed for cyanobacterial toxins using LC-MS. Dihydroanatoxin-a was detected in mat materials from two of the four sites (0.6–133 ng/g wet weight) while water samples remained toxin-free over the course of the sampling period; no other cyanobacterial toxins were detected. DNA sequencing analysis of cyanobacterial isolates yielded a total of 11 genera, including Geitlerinema, Tyconema, Pseudanabaena, and Phormidium/Microcoleus, taxa known to produce anatoxins, including dihydroanatoxin, among other cyanotoxins. Analyses indicate that low daily upriver dam discharge, higher TP and NO3 concentrations, and day of the year were the main parameters associated with the presence of toxic floating cyanobacterial mats. [ABSTRACT FROM AUTHOR]

Jenny Davis was among the first small, but significant tranche of women field biologists in the Pacific Region. She was born in Tasmania and developed a fascination with freshwater systems at an early age. Despite the paucity of female role models, freshwater ecology evolved into her research career track at the University of Tasmania where she completed her Honours degree (Zoology; 1976) and PhD (Freshwater Ecology; 1981). Jenny started her first academic position as a Tutor at Murdoch University in 1985. She successfully moved through the academic hierarchy where women continue to be under-represented in the senior ranks. She recently (2021) retired from her administrative and teaching responsibilities at Charles Darwin University (CDU) and approaching 70, is currently a Professor of Freshwater Ecology at CDU. An over-arching theme of her research is to understand the factors influencing the persistence of groundwater and surface water ecosystems. She has worked on the impacts of multiple stressors on springs, wetlands and arid zone waterbodies. She serves as a compelling role model for young scientists struggling to have a satisfying work-life balance. Jenny single-parented a son while conducting field work, teaching, publishing, serving as an academic administrator and being a prolific and successful grant writer. Jenny was also an exceptional mentor to a diverse group of students and post-docs, many of whom have thriving careers in academia, government and industry across Australia. This paper is a biography of a woman who with talent and persistence successfully broke gender barriers in Australian freshwater ecology and academia. Jenny Davis was among the first small, but significant tranche of female field biologists in the Pacific Region. Jenny is one of the few women to be promoted to the academic rank of Professor in Australian sciences. Her current research involves answering two questions: (1) how much water does the environment need; and (2) how important are isolated aquatic waterbodies for the conservation of Australia's freshwater biota? This paper is a brief biography of Jenny. [ABSTRACT FROM AUTHOR]

The globally threatened European eel (Anguilla anguilla) is the only freshwater fish native to Macaronesia. Despite being a keystone species to freshwater habitats, little is known about its population, environmental associations and conservation requirements in oceanic islands.The density and geographical‐related factors influencing the distribution of A. anguilla in the subtropical Archipelago of Madeira (Portugal) were examined. Data on the species occurrence was initially collected using an online survey addressed to citizens. Eels were then sampled through electrofishing in 31 sampling sites along 11 streams on Madeira Island, and eel‐habitat associations were investigated using LMMs and GLMMs. One stream was also sampled in Porto Santo Island.The presence of A. anguilla was confirmed in the two islands of the archipelago with streams (Madeira and Porto Santo). Eels are distributed throughout Madeira Island, being more abundant – particularly small size individual– at lower altitudes (mostly below 150 m). The number of weirs was an important predictor of eel density, suggesting that these flood‐control structures limit their upstream migration.This study represents a pioneer sampling effort of the European eel in Madeira and results provide much‐needed baseline information on the species distribution and related environmental factors in oceanic islands. While most eel research has historically focused on mainland habitats where dams pose a significant threat to eel habitats, our study underscores the critical importance of addressing smaller, often overlooked barriers that may also cause habitat fragmentation.The European eel is a panmictic species, thus, the conservation of the Macaronesian subpopulations can have substantial benefits for its global recovery. A comprehensive investigation of the impact of man‐made obstacles on eel habitat is still needed. Similarly, other common threats such as interactions with non‐indigenous species and infection by Anguillicola crassus should be a research priority in future studies. [ABSTRACT FROM AUTHOR]

Despite supporting a disproportionately large fraction of the global biodiversity, freshwater ecosystems are ranked as the most highly threatened habitats ahead of both terrestrial and marine ecosystems. Furthermore, many regions are still characterized by limited knowledge on taxonomy and ecology of freshwater fishes. The need for ecological information in understudied regions is important particularly where there are recent discoveries of new species and unique lineages and for threatened and endangered taxa that require conservation management.This study evaluated the trophic ecology of two freshwater fish species Sandelia bainsii and Amatolacypris trevelyani that are both classified as endangered in the International Union for Conservation of Nature (IUCN) Red List. These two species, which are narrow‐range endemics in the Eastern Cape, South Africa, comprise allopatric lineages whose ecology is poorly known. This study used stable isotope analysis to evaluate the food web patterns, explore the trophic niche dynamics and estimate the prey source contributions for the two species in different headwater habitats.The fishes isotopic niche sizes were spatially variable, suggesting the likely importance of stochastic variation in resource availability and probable interspecific interactions. The three lineages within S. bainsii exhibited low isotopic niche overlap onto those of sympatric fishes in most habitats. Isotopic mixing model revealed that these lineages' diets were mostly dominated by gatherers/collectors. In comparison, the two lineages within A. trevelyani exhibited high niche overlap with other species and generally had variable diets.Despite the low and high niche overlap patterns of S. bainsii and A. trevelyani, respectively, the isotopic niche overlap patterns of co‐occurring species onto those of the former suggest the likely lack of competitive hierarchies. The trophic niche patterns of these two endangered species helped to shed some light on the potential invasion risks by non‐piscivorous fishes with opportunistic feeding habits, which could exert competitive interspecific interactions. [ABSTRACT FROM AUTHOR]

This investigation delves into the ecological dimensions of freshwater snails in the vicinity of an artificially created lake. The aim of this research was to comprehend the distribution, prevalence, and variety of freshwater snail species within the ecosystem surrounding the manmade lake. The study spanned from August to November 2023, conducted at three distinct sample stations (I, II, and III), with bi-weekly sample collections. Standard keys were employed for the identification of snails, and the Shanon-Weiner and Simpson's similarity indices were used to explore the diversity of snail species. Throughout the study, a total of 311 individuals representing three distinct species encountered in this study were documented. Acathina fulica exhibited the highest abundance (129 individuals), while Pomacea bridgesii displayed the lowest abundance (66 individuals). The month of August registered the highest population (122 individuals), contrasting with the lowest count in November (37 individuals). Abundance varied across stations, with Station II recording the lowest (77 individuals) and Station III the highest (116 individuals). Regarding diversity, Pomacea bridgesii emerged as the most diverse species (0.3670 & 0.3662), while Littorina littorea exhibited the least diversity (0.0000) across the stations. This investigation contributes valuable insights into the dynamics of freshwater snail populations in the periphery of artificial lakes, shedding light on their distribution patterns and ecological interactions. [ABSTRACT FROM AUTHOR]

An ecological monitoring survey of the freshwater ecosystem of the Pyasachnik Dam was carried out in the period 2011-2016. The main indicators of surface water quality such as temperature, transparency, electrical conductivity, dissolved oxygen, N–NH4, N–NO2, N–NO3, orthophosphates P, total nitrogen, total phosphorus, and chlorophyll a content were monitored. Hereafter, the obtained results are discussed by years and seasons. The chemical status and ecological potential of the freshwater ecosystem were determined. The investigated surface waters are suitable for irrigation, but with a permanent mandatory monitoring. [ABSTRACT FROM AUTHOR]

Helicostoa sinensis E. Lamy, 1926 is a unique freshwater gastropod species with a sessile habit. This enigmatic species was first found cemented on river limestones from China about 120 years ago and described together with the genus. It was never collected again and has been considered monotypic. Here, we report the rediscovery of Helicostoa from several rivers in China, and describe a second species of this genus based on a comprehensive study. In addition to the unique sessile habit of both species, the new Helicostoa species presents one of the most remarkable cases of sexual dimorphism within molluscs. Only the adult female is sessile and the original aperture of the female is sealed by shell matter or rock, while an opening on the body whorl takes the function of the original aperture. The male is vagile, with a normal aperture. Our results confirm the recently suggested placement of Helicostoa within the family Bithyniidae. The sessility of Helicostoa species is considered as an adaption to the limestone habitat in large rivers. The extreme sexual dimorphism and secondary aperture of females are considered as adaptations to overcome the obstacles for mating and feeding that come with a sessile life style. [ABSTRACT FROM AUTHOR]

Multicellular organisms engage in complex ecological interactions with microorganisms, some of which are harmful to the host’s health and fitness (e.g., pathogens or toxin-producing environmental microbiota), while others are either beneficial or have a neutral impact (as seen in components of host-associated microbiota). Although environmental microorganisms are generally considered to have no significant impact on animal fitness, there is evidence suggesting that exposure to these microbes might be required for proper immune maturation and research in vertebrates has shown that developing in a sterile environment detrimentally impacts health later in life. However, it remains uncertain whether such beneficial effects of environmental microorganisms are present in invertebrates that lack an adaptive immune system. In the present study, we conducted an experiment with field-collected Hydra oligactis, a cold-adapted freshwater cnidarian. We cultured these organisms in normal and autoclaved lake water at two distinct temperatures: 8°C and 12°C. Our findings indicated that polyps maintained in sterilized lake water displayed reduced population growth that depended on temperature, such that the effect was only present on 8°C. To better understand the dynamics of microbial communities both inhabiting polyps and their surrounding environment we conducted 16S sequencing before and after treatment, analyzing samples from both the polyps and the water. As a result of culturing in autoclaved lake water, the polyps showed a slightly altered microbiota composition, with some microbial lineages showing significant reduction in abundance, while only a few displayed increased abundances. The autoclaved lake water was recolonized, likely from the surface of hydra polyps, by a complex albeit different community of bacteria, some of which (such as Pseudomonas, Flavobacteriaceae) might be pathogenic to hydra. The abundance of the intracellular symbiont Polynucleobacter was positively related to hydra population size. These findings indicate that at low temperature environmental microbiota can enhance population growth rate in hydra, suggesting that environmental microorganisms can provide benefits to animals even in the absence of an adaptive immune system. [ABSTRACT FROM AUTHOR]

Zooplankton plays a pivotal role in lentic water bodies, linking planktonic primary producers to higher trophic levels and being a cornerstone of the planktonic food web of ponds and lakes. Because of its ease of culture, large size, rich ecology, abundance in northern temperate lakes where limnology is rooted, and the ability to work with clones, Daphnia has, in the last centuries grown to become a key model system in ecology, evolution, and ecotoxicology. Consequently, a vast majority of freshwater zooplankton ecology focuses on the role of Daphnia. While generating essential insights, this has also deviated attention from the broad ecological impact of other zooplankton. Here, we emphasize how other zooplankton taxa have an important impact in nature - often in qualitatively different ways than Daphnia. We illustrate this point by focusing on two key zooplankton functions (herbivory and stoichiometry) and suggest research to capitalize on the success story of mechanistic ecological, eco-evolutionary, and genomic Daphnia work to develop a richer set of model organisms. We currently have the tools to do so and integrating mechanistic insights in multispecies settings would foster a better understanding of the rich diversity and ecology of freshwater zooplankton. [ABSTRACT FROM AUTHOR]

Freshwater mussels are both critically important in their ecosystems and rapidly declining around the world. Damming is a key reason for this decline in many locations because it affects the flow and turbidity of river systems, leading to numerous detrimental effects on benthic communities. Although the ecological effects of impoundment have been well studied on timescales ranging from years to decades, the ecological effects of impoundment on longer (50–100 years) timescales are less well understood, with a key question being: how long after the building of dams and impoundments do we expect community structure to continue changing? In this study, we explore historical changes in the freshwater mussel assemblages in Kentucky Lake (dammed in 1944) using decades-long collections housed at Murray State University in combination with other historical records. After digitizing these collections and applying a robust rarefaction protocol to account for uneven sampling, we quantify changes in unionid assemblage structure alongside coeval water quality data collected through the Kentucky Lake Long-Term Monitoring Program. We find that subsampled richness exhibited declines after dam construction with losses among opportunistic taxa, channelization-tolerant taxa, and impoundment-intolerant taxa. We also find increases in the proportions of equilibrium taxa throughout the dataset. Overall, the assemblage composition reached an equilibrium by the year 2000 (50 years after impoundment). In concert, river water quality data show a decline in turbidity and increase in light penetration in the period 1988–2020. Although the geohistorical records treated in this study are patchy in time, we argue that they are nonetheless valuable and illustrate that freshwater ecosystems may serve as potential sites of restoration decades after anthropogenic disturbance. In turn, this emphasizes the importance of geohistorical collections to studying long-term changes in community structure and developing strategies for conservation and environmental remediation. [ABSTRACT FROM AUTHOR]

Stocking is one of the foremost tools in the inland fisheries management toolbox, but it comes with both opportunities and risks. Stocking is often used as compensation for depleted wild populations, particularly where recruitment processes have been disrupted, but it can introduce disease, disrupt community structures, reduce genetic integrity, and cause conflicts between fishery stakeholders. Despite its widespread use, examples of effective stocking for food fisheries in inland waters are sparse in the peer‐reviewed literature. Nevertheless, it is well established that stocking is frequently used to maintain fish yield, so there is a need to conduct the practice in a robust manner that minimises the potential risks. This paper serves as the front matter for a special section of Fisheries Management and Ecology focused on fresh waters feeding the world, which resulted from two panel sessions, one focused on aquaculture and one focused on stocking, hosted by the international InFish research network (https://infish.org/). The paper highlights current practices of fish stock enhancement in inland waters for food, examines potential synergies and interactions of stock enhancement programmes with aquaculture, and provides an outline framework for responsible management of fish stock enhancement. [ABSTRACT FROM AUTHOR]