Conservation Of Freshwater Fishes Research Articles

Group behavior and tolerance of Eurasian minnow (Phoxinus phoxinus) in response to tones of differing pulse repetition rate.

Behavioral guidance systems are commonly used in freshwater fish conservation. The biological relevance of sound to fish and recorded responses to human-generated noise supports the viability of the use of acoustics as an effective stimulus in such technologies. Relatively little information exists on the long-term responses and recovery of fish to repeated acoustic exposures. In a controlled laboratory study, the response and tolerance of Eurasian minnow (Phoxinus phoxinus) shoals to tonal signals (150 Hz of 1 s pulse duration) differing only in temporal characteristics ("continuous," "slow," "intermediate," or "fast" pulse repetition rate) were investigated. In comparison to independent control groups, fish increased their mean group swimming speed, decreased inter-individual distance, and became more aligned in response to the onset of all four acoustic treatments. The magnitude of response, and time taken to develop a tolerance to a treatment differed according to pulse repetition rate. Groups were found to have the greatest and longest lasting response to tone sequences tested in this study when they were pulsed at an intermediate rate of 0.2 s-1. This study illustrates the importance of understanding the response of fish to acoustic signals, and will assist toward the development of longer-term effective acoustic guidance systems.

Using endemic freshwater fishes as proxies of their ecosystems to identify high priority rivers for conservation under climate change

Freshwater ecosystems are among the most endangered ecosystems on Earth and are vulnerable to climate change. Studies have shown that climate change has already altered the phenology and distribution of freshwater species. However, there are still major gaps in our understanding of potential impacts of climate change on freshwater ecosystems and their organisms. Freshwater fishes were used as effective indicators for identifying the degree, direction and scale of changes in aquatic ecosystems and as indicators of freshwater ecosystem quality and health. However, they are rarely used to determine sensitive freshwater ecosystems to climate change using species distribution modeling. We modeled current and future distribution of 15 endemic freshwater fish in Iran to identify winners and losers of climate change and high priority rivers for conservation under climate change. In addition, we assessed changes in elevational distribution of the species under climate change. Our results showed that five species will lose some parts of their current suitable range under climate change while ten species will gain new suitable habitats. Considering their restricted range, endemic species are of special conservation concern, so results of this study can be used for conservation of endemic freshwater fishes. Species which were identified to be negatively affected by climate change should be prioritized for monitoring and conservation and can be the subject of future conservation programs. Using the five species for which reductions of range size were predicted, 20 rivers were identified as targets of future conservation actions to reduce negative impacts of climate change on freshwater fish.

Species diversity and conservation of freshwater fishes in the Yellow River basin

Species diversity and conservation of freshwater fishes in the Yellow River basin

Assessing the Species in the CARES Preservation Program and the Role of Aquarium Hobbyists in Freshwater Fish Conservation

Freshwater fish represent half of all fish species and are the most threatened vertebrate group. Given their considerable passion and knowledge, aquarium hobbyists can play a vital role in their conservation. CARES is made up of many organizations, whose purpose is to encourage aquarium hobbyists to devote tank space to the most endangered and overlooked freshwater fish to ensure their survival. We found the CARES priority list contains nearly six hundred species from twenty families and two dozen extinct-in-the-wild species. The major families were typically those with the largest hobbyist affiliations such as killifish, livebearers, and cichlids, the latter containing half of CARES species. CARES included every IUCN threatened species of Pseudomugilidae and Valenciidae, but only one percent of threatened Characidae, Cobitidae, and Gobiidae species. No Loricariidae in CARES were in the IUCN red list as they have not been scientifically described. Tanzania and Mexico contained the largest amount of species, with the latter containing the most endemics. Many species were classified differently than the IUCN, including a third of extinct-in-the-wild species classified as least concern by the IUCN. This vast disconnect exemplifies the importance of future collaboration and information exchange required between hobbyists, the scientific community, and conservation organizations.

Genetic diversity and phylogenetic relationship among Anabantoidei fish (Anabantiformes) in South Kalimantan, Indonesia based on SDS-PAGE analysis

Abstract. Sasmita R, Mabrur, Rahmy USA, Badruzsaufari. 2019. Genetic diversity and phylogenetic relationship among Anabantoidei fish (Anabantiformes) in South Kalimantan, Indonesia based on SDS-PAGE analysis. Biodiversitas 20: 2519-2527. Protein profile is a molecular marker for diversity and phylogenetic analysis of germplasm, including Anabantoidei fish which is abundant in freshwater ecosystem of South Kalimantan. The aim of this research was to analyze genetic diversity and construct phylogenetic relationship among Anabantoidei fish based on SDS PAGE analysis. Protein was extracted from muscle tissue of six species of Anabantoidei fish and precipitated using Ammonium sulfate salt. Soluble protein content was determined using Bradford assay and then separated based on SDS-PAGE method. Genetic diversity and phylogenetic relationship were constructed using PAST software based on UPGMA method. The results showed that the soluble protein of fish muscle can be precipitated optimally in different ammonium sulfate concentration. Based on SDS-PAGE analysis, 59 different protein bands have been separated from gels with molecular weight ranging from 28.15 to 181.61 kDa. On the protein level, the Anabantoidei fish showed high genetic polymorphism (greater than 90%) with 3, 2 and 5 monomorphic bands on non-precipitated, AS-precipitated and combination between non- and AS-precipitated proteins, respectively. The phylogenetic reconstruction also exhibited that the Anabantoidei fish has the unique phylogenetic trees, especially for the combined protein datasets. This information would be useful for freshwater fish conservation and breeding programs.

Validation of close‐kin mark–recapture (CKMR) methods for estimating population abundance

Abstract Knowing how many individuals there are in a population is a fundamental problem in the management and conservation of freshwater and marine fish. We compare abundance estimates (census size, Nc) in seven brook trout Salvelinus fontinalis populations using standard mark–recapture (MR) and the close‐kin mark–recapture (CKMR) method. Our purpose is to validate CKMR as a method for estimating population size. Close‐kin mark–recapture is based on the principle that an individual's genotype can be considered a “recapture” of the genotypes of each of its parents. Assuming offspring and parents are sampled independently, the number of parent–offspring pairs (POPs) genetically identified in these samples can be used to estimate abundance. We genotyped (33 microsatellites) and aged c. 2,400 brook trout individuals collected over 5 consecutive years (2014–2018). We provide an alternative interpretation of CKMR in terms of the Lincoln–Petersen estimator in which the parents are considered as tagging the offspring rather than the offspring “recapturing” the parents. Despite various sources of uncertainty, we find close agreement between standard MR abundance estimates obtained through double‐pass electrofishing and CKMR estimates, which require information on age‐specific fecundity, and population‐ and age‐specific survival rates. Population sizes () are estimated to range between 300 and 6,000 adult individuals. Our study constitutes the first in situ validation of CKMR and establishes it as a useful method for estimating population size in aquatic systems where assumptions of random sampling and thorough mixing of individuals can be met.

Fishing for conservation of freshwater tropical fishes in the Anthropocene

Abstract The ecosystem services provided by freshwater biodiversity are threatened by development and environmental and climate change in the Anthropocene. Here, case studies are described to show that a focus on the shared dependence on freshwater ecosystem functioning can mutually benefit fisheries and conservation agendas in the Anthropocene. Meeting the threat to fish biodiversity and fisher livelihood is pertinent in developing regions where there is often a convergence between high biodiversity, high dependency on aquatic biota and rapid economic development (see Kafue River, Logone floodplain, Tonle Sap, and Rio Negro case studies). These case studies serve as evidence that biodiversity conservation goals can be achieved by emphasizing a sustainable fisheries agenda with partnerships, shared knowledge and innovation in fisheries management (see Kafue River and Kenai River case studies). In all case studies, aquatic biodiversity conservation and fisheries agendas are better served if efforts focused on creating synergies between fishing activities with ecosystem functioning yield long‐term livelihood and food security narratives. A unified voice from conservation and fisheries communities has more socio‐economic and political capital to advocate for biodiversity and social interests in freshwater governance decisions.

Can conservation targets for imperilled freshwater fishes and mussels be achieved by captive breeding and release programs? A systematic map protocol to determine available evidence

BackgroundCaptive breeding programs are one of the many tools used by conservation practitioners as a means of conserving, supporting, and supplementing populations of imperilled species. Captive breeding programs exist around the globe for freshwater mussels and fishes, but the availability of evidence exploring the effectiveness of these programs has not yet been explored using systematic map criteria. This systematic map aims to identify, collate and describe the evidence that exists on the effectiveness of captive breeding programs, for the purpose of achieving conservation targets for imperilled freshwater fishes and mussels in the wild. The outputs of this systematic map will help to inform conservation managers and policy makers who are responsible for protecting imperilled freshwater species by identifying existing information and highlighting key information gaps for captive breeding programs operating in temperate regions.MethodsThis systematic map will search for, compile, and map existing literature on the effectiveness of captive breeding programs for the conservation of imperilled freshwater fishes and mussels. The systematic map will search using five bibliographic databases, two public search engines, and 19 specialist websites and will include both primary and grey literature. All studies that discuss details related to captive breeding programs for the conservation of imperilled freshwater fishes and/or mussels in temperate regions will be included in the map. The systematic map will produce a narrative report describing the evidence, including knowledge gaps evidence clusters, and a MS-Excel searchable database of articles and extracted metadata.

Loss of endemic fish species drives impacts on functional richness, redundancy and vulnerability in freshwater ecoregions of Sundaland

Fishes are a speciose and ecologically important group within severely threatened or impacted freshwater habitats of Sundaland, whose contributions to ecosystem functioning can be inferred from their functional diversity. However, there is limited understanding of the potential impacts of anthropogenic species loss on ichthyofaunal functional diversity in the region. We therefore aimed to characterise the functional diversity of fishes across freshwater ecoregions in Sundaland, and predict potential impacts of anthropogenic species losses on functional diversity, in order to identify priority ecoregions for freshwater fish conservation. To this end, data comprising nine functional traits of 893 Sundaic freshwater fish species were compiled and analysed to compute measures of functional richness, functional redundancy and functional vulnerability. We then modelled the loss of extinction-prone species (identified using a trait-based conditional inference forest approach) within each ecoregion, and quantified the resulting impacts on functional diversity. Both functional richness and functional redundancy scale positively with species richness across ecoregions, but functional vulnerability is widespread. Functional entities comprising moderate- to large-sized omnivores or higher carnivores are particularly vulnerable, and the same is true for fishes with superiorly-oriented and toothed mouthparts. Removal of susceptible endemic species in each ecoregion resulted in the erosion of functional redundancy and exacerbation of functional vulnerability, but functional richness was relatively less impacted. Overall, our findings suggest a trajectory of accelerating impacts on functional diversity (and by extension, ecosystem function) if species losses continue unabated. From these results, we identify the Malay Peninsula Eastern Slope ecoregion as a potential conservation priority.

Living in an amphidromous world: Perspectives on the management of fish passage from an island nation

Abstract Amphidromy is a form of migratory life history typified by the reproduction of fish in freshwater environments, the early downstream dispersal of post‐hatch larvae to marine environments, and the return of small‐bodied young juveniles to freshwater environments for growth to adulthood. Island freshwater fish communities are frequently dominated by fish species with amphidromous life histories. Amphidromous life cycles leave fish communities highly susceptible to habitat modification and disruptions to connectivity across marine and freshwater environments. This means that managing waterway connectivity is fundamental to their conservation; however, the unique and often geographically restricted amphidromous communities that characterize many small island nations have received little consideration in the development of strategies for the management of fish passage. The ecology and locomotory capabilities of amphidromous species are often poorly studied, partly because their small size at migratory life stages renders current state‐of‐the‐art in situ biotelemetry methods unsuitable. The small size of fish also means that seemingly small obstructions can severely impede migrations. The steps necessary to advance the management of fish passage for island fish communities are: curating and maintaining barrier inventories; evaluating barrier permeability; developing effective barrier mitigation options; and prioritizing restoration and conservation efforts. New methods for understanding the ecology and locomotory capabilities and behaviour of amphidromous fishes are required to advance the management of fish passage for island fish communities. Fish passage solutions that imitate natural streams, such as those promoted in new guidelines in New Zealand, may be the most effective way of improving waterway connectivity; however, integrated approaches to freshwater fish conservation that account for meta‐population dynamics, in combination with the management of fish passage, are necessary to optimize conservation outcomes for amphidromous species.

Toward a better understanding of freshwater fish responses to an increasingly drought-stricken world

Drought is a constant and important consequence of natural climatic processes and most freshwater fishes have adaptations to counter its effects. However, a changing global climate coupled with increasing human demand for water is reducing the availability of fresh water to fishes and contributing to more frequent and intense drought around the globe. A clear understanding of how fishes, fish habitat, and fisheries are affected by extended drought is needed to help resolve conflicts over water. We therefore identify key questions and research themes to promote the conservation of freshwater fishes as drought increases in length, frequency and severity. (1) How does drought affect fish habitat? (2) What is drought tolerance in fishes? (3) What are drought refuges for fishes? (4) What kills fish during drought? (5) What is the nature of species succession in drought-stricken waters? (6) What are the long-term consequences of drought to fishes? (7) How does climate change affect drought-fish interactions? (8) How does drought influence fisheries? Our limited ability to provide answers to these questions indicates that fish diversity and abundance worldwide is threatened by drought. Planning, including collection of long-term data, is necessary so that conservation and water re-allocation strategies can be implemented in a timely manner to maintain habitats necessary to support biodiversity during drought periods. Without increased understanding of physiological and behavioural factors that determine the tolerance of fishes to drought, it will not be possible to establish realistic targets for management and restoration of populations and species confronting increasing drought frequency and severity.

Distribution strategy of Nimbapanchax petersi (Sauvage, 1882) and Epiplatys chaperi sheljuzhkoi (Poll, 1953) fish, in Banco National Park (Côte d’Ivoire, West Africa)

Objective: This study highlights the distribution strategy of two fish species of Nothobranchiidae ( Nimbapanchax petersi and Epiplatys chaperi sheljuzhkoi ) according to environmental variables of Banco River in the National Park of Banco in order to characterize their preferential habitat. Methodology and results: Sampling was conducted from December 2015 to January 2017 using dip nets. Four defined stations (B1 to B4) along the Banco River were visited. A total of 397 samples of Nimbapanchax petersi were collected. This species is more abundant upstream with 82.87% of the sampling. However, the 186 individuals of Epiplatys chaperi sheljuzhkoi captured were distributed homogeneously over the entire river along an upstream-downstream gradient. Canonical Correlation Analysis (CCA) has shown that the nature of the substrate (clay-mud mixture, rocks and deadwood-foliage mixture) and dissolved oxygen levels are critical factors in the distribution pattern of these species in the Banco River. Epiplatys chaperi sheljuzhkoi select habitats with mud, clay and deadwood-foliage mixture while Nimbapanchax petersi target rocky and more oxygenated environments. Conclusion and application of results: These results, which are essential data on the ecology of aquatic species in the wild, could contribute to ensure better conservation of small freshwater fish. These baseline data for future studies will enable a sustainable stock conservation policy for these species to be put in place. In addition, faced with the anthropogenic pressures of the surrounding communities on this environment, park managers should pay more attention to the preservation of biodiversity in general and to the two species of Nothobranchiidae in particular. Keywords: Distribution, Nothobranchiidae, aquarists, environmental factors, Banco River

Conservation of freshwater fishes of the Western Ghats Hotspot, India

Event Abstract Back to Event Conservation of freshwater fishes of the Western Ghats Hotspot, India Rajeev Raghavan1* 1 Kerala University of Fisheries and Ocean Studies, India With over 300 species, of which ~65% are endemic, the freshwater fish fauna of the Western Ghats mountain ranges is one of the richest and unique in the tropical world. The endemism is also just not restricted to the species level, as there is at least 1 family and 19 genera of fish that are unique to this region. Freshwater fish has also been part of history and culture in the Western Ghats since several centuries, and they are intricately linked to the daily life of millions of rural poor. Despite these striking statistics, the ichthyofauna of the Western Ghats Biodiversity Hotspot is threatened by a variety of stressors including large-scale deforestation, hydropower and drainage basin alterations, pollution, overharvest and alien species, resulting in over one-third of the fish fauna assessed as threatened on the IUCN Red List. While a number of species have experienced catastrophic population declines in the last few decades, several enigmatic new species (and genera) continue to be discovered from the Western Ghats indicating that our knowledge on the ichthyofauna of this region is still far from being complete. With increasing consciousness regarding the conservation of aquatic biodiversity, several conservation initiatives ranging from prioritisation and design of Key Biodiversity Areas (KBA) and Alliance for Zero Extinction (AZE) sites, to community conservation zones and temple sanctuaries, and the development of policies for protecting inland and freshwater fish species, have been initiated in the region. Acknowledgements IUCN Freshwater Biodiversity Unit, Cambridge Zoo Outreach Organization, Coimbatore, India Keywords: Endemic, South Asia, Threatened species, Mahseer, Data deficient Conference: XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019. Presentation Type: Plenary Invited Presentation Topic: THREATS AND CONSERVATION Citation: Raghavan R (2019). Conservation of freshwater fishes of the Western Ghats Hotspot, India. Front. Mar. Sci. Conference Abstract: XVI European Congress of Ichthyology. doi: 10.3389/conf.fmars.2019.07.00151 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Jun 2019; Published Online: 14 Aug 2019. * Correspondence: Dr. Rajeev Raghavan, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, 682506, India, rajeevraq@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rajeev Raghavan Google Rajeev Raghavan Google Scholar Rajeev Raghavan PubMed Rajeev Raghavan Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Hydrographic correlates of within‐river distribution and population genetic structure in two widespread species of mountain galaxias (Teleostei, Galaxiidae) in southern Australia

Abstract Closely related species may have different patterns of distribution and spatial population structure in common landscapes, which can have implications for conservation of the species if they are vulnerable. The Australian mountain galaxias species complex has recently been split into 15 described species, 11 of which are threatened. In this study, we assessed the distribution and landscape genetic structure of two mountain galaxias species (Galaxias olidus and Galaxias oliros) in the Goulburn–Broken catchment (Murray–Darling Basin) in relation to hydrographic descriptors of river terrain, network and hydrology. We also assessed small‐scale population structure in juvenile G. oliros in tributary streams of the Goulburn River (the Granite Creeks). Analyses of distribution revealed that G. olidus mostly occurs in smaller streams at high elevations with steep valley slopes and high stream gradients downstream, whereas G. oliros mostly occurs in larger downstream waterways with higher magnitude and variability of stream flow. Population genetic structure in G. olidus was much greater than for G. oliros, with 17 of the 19 sampled locations resolved as genetically distinct populations for G. olidus, but only a single population revealed for G. oliros. Results for both species did not reflect the expectations of the stream hierarchy model or isolation‐by‐distance model. However, small‐scale spatial population structure in juvenile G. oliros in the Granite Creeks reflected the expectations of both stream hierarchy and isolation‐by‐distance models, suggesting that population structure of juveniles of this species reflects some level of spatial aggregation of closely related individuals that probably diminishes as the population ages. Higher landscape genetic structure in G. olidus was correlated with steeper stream and valley slopes, whereas no population genetic correlations were significant for G. oliros. Genetic diversity in G. olidus was higher in areas of greater hydrological variability, suggesting that populations in hydrologically variable areas function as a metapopulation and have a more diverse gene pool than populations in areas with lower hydrological variability. In contrast, genetic diversity in G. olidus was lower in higher elevation areas with steep valley slopes, suggesting that smaller but more stable populations occur in high elevation streams with high perenniality and low interannual variability of flows. Our results are consistent with other studies that highlight the importance of supporting natural hydrological regimes and natural patterns of hydrological connectivity for conservation of vulnerable freshwater fish.

The extinction of the Catarina pupfish Megupsilon aporus and the implications for the conservation of freshwater fish in Mexico

AbstractExtinctions are occurring at an unprecedented rate as a consequence of human activities. Vertebrates constitute the best-known group of animals, and thus the group for which there are more accurate estimates of extinctions. Among them, freshwater fishes are particularly threatened and many species are declining. Here we report the extinction of an endemic freshwater fish of Mexico, the Catarina pupfish Megupsilon aporus, the sole species of the genus Megupsilon. We present a synopsis of the discovery and description of the species, the threats to, and degradation of, its habitat, and the efforts to maintain the species in captivity before it became extinct in 2014. The loss of the Catarina pupfish has evolutionary and ecological implications, and highlights the crisis of freshwater fish extinctions. It is a warning of the likely fate of more than 200 freshwater fish species threatened with extinction in Mexico. To save these species, the country urgently needs a national strategy to articulate a bold conservation effort, with better policies on ecosystem management and water use.

State- and Regional-Scale Patterns and Drivers of Freshwater Fish Functional Diversity in the Southeastern USA

Understanding biodiversity patterns and their drivers across large spatial scales has become a necessary component of addressing complex multiscale conservation challenges. Increasingly, functional diversity measures are being used to provide insight on the ecological integrity of ecosystems. We estimated functional diversity at two different spatial extents using data sets of contrasting sampling intensity and time duration and compared these two different approaches. For our regional-scale analysis, we used large-scale fish sampling data sets and identified 397 species across subbasins within the southeastern USA. For our state-scale analysis, we used data from the South Carolina Department of Natural Resources Statewide Stream Assessment through which 101 species were collected from wadeable streams across South Carolina. For all fish species, we scored trophic and reproductive traits and measured trophic and reproductive functional diversity across subbasins and South Carolina streams. We assessed differences in functional diversity between level III ecoregions, quantified the influence of imperiled and invasive species on functional diversity, and modeled relationships between functional diversity and environmental variables at the state scale using Random Forest regression. At both scales, we found support for higher trophic functional diversity in high-elevation ecoregions, while reproductive functional diversity was generally higher in low-elevation ecoregions. The inclusion of imperiled species increased functional diversity estimates, while invasive species decreased functional diversity estimates except for reproductive functional diversity at the regional scale. Environmental variables that correlated with functional diversity at the state scale included forest cover, elevation, and conductivity. The observed spatial patterns of functional diversity, the environmental variables identified as predictors of functional diversity, and knowledge of how imperiled and invasive species influence functional diversity can be used to guide freshwater fish conservation efforts across the southeastern U.S. region. Additionally, these findings highlight the utility of data from intensive, standardized, broad-scale aquatic surveys in addressing these and similar questions regarding freshwater diversity.

Invasive Rainbow Trout (Oncorhynchus mykiss) Are Not Affected by Different Land Uses in a Multi-Use, Mediterranean Climate Landscape

Land use carries implications for freshwater fish conservation. Plantation forestry practices have been shown to have negative impacts on resident fish fauna, but little work has been conducted to assess these impacts on invasive vs. native fish populations. Ten headwater catchments in the Mediterranean climate zone of Chile were used to assess the impacts of land use (pine plantations vs. native forests) on fish condition (length-weight relationship) and abundance (catch-per-unit-effort (CPUE)) of the invasive trout Oncorhynchus mykiss and the threatened native catfish Nematogenys inermis. Negative impacts on trout condition were associated with a lack of canopy cover and river topology. The presence of N. inermis was associated with catchment factors less favourable to trout. Current environmental regulations and forestry management practices do not appear to create negative pressures on invasive trout from land use practices, despite expectations from the literature. Assessing how land use management regulations impact invasive and native fishes should be a part of species conservation and territorial planning.

Comprehensive analysis of >30 years of data on stream fish population trends and conservation status in Bavaria, Germany

Freshwater fishes are among the most threatened groups of vertebrates, with 39% of all European fish species facing extinction. Herein, we provide a comprehensive analyses of historical data as well as fish monitoring data from 1989 through 2013 from Bavaria, Germany. The results of this study indicate that the most pronounced species-turnover already had occurred before the 1990s. Severe loss of species (21 out of 69 species lost until 1990s), decrease in spatial distribution (51 species, 27 reduced to <50% of historical distribution), decrease of abundance, shifts towards potamal species and the establishment of novel communities due to increasing colonization with non-native species was evident. Declines were strongest for gravel-spawning species of the hyporhitral and epipotamal in medium-sized and large rivers (e.g. grayling (Thymallus thymallus), nase (Chondrostoma nasus), barbel (Barbus barbus)), suggesting that effects of increasing water temperatures and increased fine sediment loads probably strongly contribute to the decline of those species. Our results generally confirmed the validity of current conservation status for most species, but also identified species (dace (Leuciscus leuciscus), chub (Squalius cephalus), trout (Salmo trutta), minnow (Phoxinus phoxinus), nase and barbel) and habitats (medium-sized and large rivers) that deserve higher priority in conservation management. More consistent sampling of the same sites over years and a quantitative monitoring of environmental impact factors in appropriate spatial and temporal resolution is crucial to allow a future prioritization in freshwater fish conservation.

Multiple‐stressor effects on freshwater fish: Importance of taxonomy and life stage

AbstractInteractions among multiple anthropogenic stressors threaten freshwater fish and pose challenges for fisheries management and conservation. Previous studies of multiple‐stressor effects on freshwater fish suggest a prevalence of antagonistic interactions. However, taxonomy, life stage and/or environmental context likely modify the magnitude and direction of fish responses to multiple stressors. Stressor intensity, impact mechanism, exposure time and ecosystem size may further affect interaction outcomes. Large‐scale studies quantifying how these variables moderate stressor interactions are lacking. To address this knowledge gap, we performed a meta‐analysis of 29 factorial multiple‐stressor experiments to examine the influence of seven potential moderator variables on the magnitude and direction of stressor interactions. Using weighted random‐effects meta‐analytic models, we demonstrate the importance of taxonomic identity and life stage for interaction outcomes. In particular, Cypriniformes showed stronger antagonisms than Salmoniformes, as did larval fish compared to juveniles. Interaction outcomes also varied among the measured fish responses with survival yielding stronger antagonisms than biomass. Increasing experimental duration and volume of the experimental units both drove interactions towards synergisms, supporting findings from previous studies that synergisms take time and space to develop. In an era when the number of stressors affecting freshwater systems is increasing rapidly, our study provides a vital step towards identifying generalities in multiple‐stressor outcomes and thus improved predictions of multiple‐stressor impacts. Furthermore, our meta‐analysis complements studies in real streams, rivers and lakes by providing an experimentally derived context for the growing number of multiple‐stressor assessments in research, management and conservation of freshwater fish.

어류를 이용한 한국의 하천생태계 건강성 평가

The objective of this study was to describe the development and testing of an initial ecological health assessment model, based on the index of biological integrity (IBI) using fish assemblages, before establishing the final and currently used model for ecological health assessment, conservation and management of freshwater fish in Korea. The initial fish IBI model was developed during 2004~2006 and included 10 metrics, and in 2007 the final IBI 8-metric model was established for application to streams and rivers in four major Korean watersheds. In this paper, we describe how we developed fish sampling methods, determined metric attributes and categorized tolerance guilds and trophic guilds during the development of the multi-metric model. Two of the initial metrics were removed and the initial evaluation categories were reduced from six to four (excellent, good, fair, poor) before establishing the final national fish model. In the development phase, IBI values were compared with chemical parameters (BOD and COD as indicators of organic matter pollution) and physical habitat parameters to identify differences in IBI model values between chemical and physical habitat conditions. These processes undertaken during the development of the IBI model may be helpful in understanding the modifications made and contribute to creating efficient conservation and management strategies for stream environments to be used by limnologists and fish ecologists as well as stream/watershed managers.