Suchergebnisse

The European eel (Anguilla anguilla) is a catadromous fish species, with population trends presenting significant declines over the last four decades. These declines throughout their range have resulted in their classification as 'critically endangered' by the IUCN. In addition, the European Union has implemented specific legislation surrounding A. anguilla, requiring member states to develop eel management plans [The EC Eel Regulation (1100/2007)]. Aimed to facilitate increased recruitment, these regulations state >40% of historic eel biomass should be allowed safe passage between inland waters and the sea. Cyprus however, applied and were granted an exemption from this, on the basis that there are no rivers on the island of suitable habitat and flow regimes which naturally host A. anguilla (2009/310/EC). Following this decision, recent findings have suggested that historically eels were more widespread in Cyprus than previously recognised. Indeed, a study by Zogaris et al. (2012) indicated that eels are likely the island's most widespread native species. Cyprus' freshwater lotic systems are dominated by intermittent rivers and streams, however the natural state and fish populations of these systems are poorly understood. The freshwaters of the island are now heavily fragmented, and with an estimated 108 dams retaining water are host to one of the highest densities of dam reservoirs in Europe. These interruptions to longitudinal connectivity lead to degraded freshwater systems in the lowlands, but despite this the island does have perennial freshwaters, particularly in the western side of the island and at higher elevations. If A. anguilla are indeed present in inland Cyprus, one key deterministic factor on their survival could be access to perennial summer refugia. Here, multiple monitoring methods were applied to build knowledge on present day eel distribution in Cyprus. By increasing knowledge regarding distribution, we can re-evaluate whether conservation initiatives are in fact justified and worthwhile. ...

The European eel (Anguilla anguilla) is a catadromous fish species, with population trends presenting significant declines over the last four decades. These declines throughout their range have resulted in their classification as 'critically endangered' by the IUCN. In addition, the European Union has implemented specific legislation surrounding A. anguilla, requiring member states to develop eel management plans [The EC Eel Regulation (1100/2007)]. Aimed to facilitate increased recruitment, these regulations state >40% of historic eel biomass should be allowed safe passage between inland waters and the sea. Cyprus however, applied and were granted an exemption from this, on the basis that there are no rivers on the island of suitable habitat and flow regimes which naturally host A. anguilla (2009/310/EC). Following this decision, recent findings have suggested that historically eels were more widespread in Cyprus than previously recognised. Indeed, a study by Zogaris et al. (2012) indicated that eels are likely the island's most widespread native species. Cyprus' freshwater lotic systems are dominated by intermittent rivers and streams, however the natural state and fish populations of these systems are poorly understood. The freshwaters of the island are now heavily fragmented, and with an estimated 108 dams retaining water are host to one of the highest densities of dam reservoirs in Europe. These interruptions to longitudinal connectivity lead to degraded freshwater systems in the lowlands, but despite this the island does have perennial freshwaters, particularly in the western side of the island and at higher elevations. If A. anguilla are indeed present in inland Cyprus, one key deterministic factor on their survival could be access to perennial summer refugia. Here, multiple monitoring methods were applied to build knowledge on present day eel distribution in Cyprus. By increasing knowledge regarding distribution, we can re-evaluate whether conservation initiatives are in fact justified and worthwhile. In 2020 environmental DNA metabarcoding was applied, 130 samples were taken across 26 freshwater sites to provide an up-to-date snapshot of eel distribution. In addition to this, temporal trends were considered based on an island wide fish monitoring programme spanning 2009 - 2019 which predominantly used electric fishing. Overall the results suggest that A. anguilla is widespread in western lowland Cyprus; 11/26 study sites (31/130 samples) tested positive for eel using eDNA metabarcoding, while eels were captured in 61/299 surveys (355 individuals) over the 10 year fish monitoring programme. The trends in eel distribution are highly concordant across methods, although not all sites were monitored with both methods (Fig. 1). These data indicate widespread eel recruitment in lowland freshwaters, but a lack of eels at higher elevation perennial areas. Lowland perennial areas are few and far between, however results here suggest they are abundant in A. anguilla. While higher elevation areas had higher overall freshwater fish species richness suggesting good habitat quality, the lack of the migratory eel in upper reaches indicates that barriers including dam structures may be preventing access for such migratory fish species. Environmental DNA detected eels in intermittent outlet flows of dams, but only in 2/9 reservoirs surveyed. We provide evidence for present day widespread eel recruitment in Cyprus' inland freshwaters, however highlight the need to increase connectivity to inland perennial systems in order to enhance survival of this critically endangered species at its eastern most range.

The climate change in the Mediterranean area is expected to have significant impacts on the aquatic ecosystems and particular in the mountain rivers and streams that often host important species such as the Salmo farioides, Karaman 1938. These impacts will most possibly affect the habitat availability for various aquatic species resulting to an essential alteration of the water requirements, either for dams or other water abstractions, in order to maintain the essential levels of ecological flow for the rivers. The main scope of this study was to assess potential climate change impacts on the hydrological patterns and typical biota for a south-western Balkan mountain river, the Acheloos. The altered flow regimes under different emission scenarios of the Intergovernmental Panel on Climate Change (IPCC) were estimated using a hydrological model and based on regional climate simulations over the study area. The Indicators of Hydrologic Alteration (IHA) methodology was then used to assess the potential streamflow alterations in the studied river due to predicted climate change conditions. A fish habitat simulation method integrating univariate habitat suitability curves and hydraulic modeling techniques were used to assess the impacts on the relationships between the aquatic biota and hydrological status utilizing a sentinel species, the West Balkan trout. The most prominent effects of the climate change scenarios depict severe flow reductions that are likely to occur especially during the summer flows, changing the duration and depressing the magnitude of the natural low flow conditions. Weighted Usable Area-flow curves indicated the limitation of suitable habitat for the native trout. Finally, this preliminary application highlighted the potential of science-based hydrological and habitat simulation approaches that are relevant to both biological quality elements (fish) and current EU Water policy to serve as efficient tools for the estimation of possible climate change impacts on the south-western Balkan river ...

[EN] We propose the novel integrated modelling procedure 3H-EMC for the determination of the environmental flow in rivers and streams; 3H-EMC combines Hydrological, Hydrodynamic and Habitat modelling with the use of the Environmental Management Classes (EMCs) that are defined by the Global Environmental Flow Calculator. We apply 3H-EMC in the Sperchios River in Central Greece, in which water abstractions for irrigation cause significant environmental impacts. Calculations of the hydrodynamic-habitat model, in which the large and the small chub are the main fish species, suggest discharge values that range from 1.0 m3/s to 4.0 m3/s. However, hydrological modelling indicates that it is practically difficult to achieve discharges that are higher than approximately 1.0-1.5 m3/s. Furthermore, legislation suggests significantly lower values (0.4-0.5 m3/s) that are unacceptable from the ecological point of view. This behaviour shows that a non-integrated approach, which is based only on hydrodynamic-habitat modelling does not necessarily result in realistic environmental flows, and thus an integrated approach is required. We propose the value of 1.0 m3/s as the "optimum" environmental flow for Sperchios River, because (a) it satisfies the habitat requirements, as expressed by the values of weighted useable area that are equal to 2180 and 1964 m2 for the large and small chub, respectively, and correspond to 82 and 95% of their respective maximum values, (b) it is consistent with the requirements of Environmental Classes A and B, whose percentiles are higher than 75% for discharge (77.2%) and for habitat availability (>83.5% for the large chub and >85.0% for the small chub), (c) it is practically achievable from the hydrological point of view, and (d) it is higher than the value proposed by the Greek legislation. The proposed modelling approach can be applied to any river or stream using the same or similar modelling tools, which should be linked via suitable coupling algorithms. ; Hydraulic field measurements were ...

International audience ; Non-perennial rivers and streams (NPRS) cover > 50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Plans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability - at least as far as it is possible to assess - we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems

Freshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life-history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is unevenly distributed with considerable differences in data quality and quantity among countries and species. To make conservation more effective in the future, we suggest greater international cooperation using standardized protocols and methods to monitor and manage European freshwater mussel diversity. Such an approach will not only help conserve this vulnerable group but also, through the protection of these important organisms, will offer wider benefits to freshwater ecosystems. ; The authors appreciate the extensive work of Wendell Haag and two anonymous reviewers that improved the quality of the manuscript; Arthur Bogan and David Strayer for their assistance and careful thoughts; Marco Paulo Magalhães for help with the GIS maps; Imre Potyó for the photo of Pseudanodonta complanata; the people who took part in the Belarusian data collection especially I. A. Rudakovskiy and V. M. Samoilenko (Belarusian State University), and G. M. Tischikov and I. G. Tischikov (Republican GidroMeteoCenter of Belarus); Marco Bodon and Simone Cianfanelli for valuable information on Italian populations; all the people who provided us with the data included in the French INPN database; Zdravko Hubenov, Dimitar Kozuharov, Lyubomir Kenderov and Ivan Botev for the help with the Bulgarian data collection; and I.N. Bolotov, O.V. Aksenova, I.V. Vikhrev, A. A. Makhrov, P. E. Aspholm for help with the collection and analysis of the Russian data. Financial support was provided by: The Portuguese Foundation for Science and Technology (FCT) and COMPETE funds, project 'CONBI' (Contract: PTDC/ AAC-AMB/117688/2010) and project 'ECO-IAS' (Contract: PTDC/AAC-AMB/116685/2010); The Bavarian State Ministry of the Environment and Consumer Protection through the Bavarian Mussel Coordination Office; The Federal Government of Upper Austria (Department of Nature Conservation), by the Environmental Councilor (Manfred Haimbuchner) and by the European Union; Ministry of Natural Resources and Environmental Protection Republic of Belarus, Belarusian Committee of Ecology grant 288/73 from the Belarussian State University grant 444/50 and from the Ministry of Education and Science Republic of Belarus grant 657/65; The Ministry of Science, Education and Sports of the Republic of Croatia (119-1193080-1231), Hrvatske vode and State Institute for Nature Protection; The Czech Science Foundation (13-05872S) and ESF/MŠMT (CZ.1.07/2.3.00/30.0040); Biotope Consultancy, grants from Muséum National d'Histoire Naturelle à Paris, ATM Barcode and Agence Nationale de la Recherche '6eme extinction'; Polish Ministry of Science and Higher Education grant NCN No. NN304328836; The Russian Foundation for Basic Research, RFBR (grant no. 15-04-05638, 14-04-98801_a) and The Ural Branch of RAS (no.15-12-5-3), President of the Russian Federation (grant no. MD-6465.2014.5). ; info:eu-repo/semantics/publishedVersion