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Large-scale rehabilitation in the alluvial area along the lower reaches of the Dyje River
Lusk, Stanislav ; Pražák, O. ; Lusková, Věra ; Halačka, Karel ; Vetešník, Lukáš
The Dyje River between Lednice and Bulhary was straightened, canalised, and provided with levees. Most of the alluvial area near Podivin was transformed to arable land. Due to elimination of floods, save for exceptions, areas denoted as wetlands and reed beds were qute dry for most of the year. As a result, the native fish communities typical of alluvial habitats gradually vanished from their habitats. In recent years, some 470 hectares on the left bank of the Dyje River, owned by a single private person, were transformed into a deer sanctuary. In the past two years, the arable land in that area has been gradually turned into meadows and a floodplain forest, together with restoring and enlarging the area of permanently waterlogged parts denoted as wetlands. As a result, the conditions permitting permanent occurrence of fish have been significantly improved and for a purposeful restoration of their fish communities in which native species predominate (the Carassius-Misgurnus type).
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Floodplains: special measures needed for the development and stabilisation of fish biota
Lusk, Stanislav ; Hartvich, P. ; Lojkásek, B. ; Lusková, Věra ; Pražák, O. ; Halačka, Karel ; Sovíková, L.
The preserved extent of the initial floodplains along major rivers is limited and has been distinctly altered by hydrological dynamics. The results exert a negative impact on aquatic biota, above all, fishes (the floodplains of Odra, Dyje, Lužnice rivers). The most marked changes include construction of ponds, canalization of streams with levees, absence of meadow management. The consequences: absent landscape formation activity of streams, expansion of wetland vegetation, gradual silting and downfall of alluvial habitats, their total drying, destruction of elements such as channels, ditches, river arms and other habitats, a limitation or disappearance of populations of Misgurnus fossilis, Rhodeus amarus, Cobitis spp., Carassius carassius, Leucaspius delineatus. Retrieval: maintenance of optimum condition of aquatic habitats, creation of artificial wetlands, restoration populations of protected fish species. Passive protection of habitat and species is no solution any longer.
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Revitalisation and fishes in the inundation area and the floodplain forests along the lower reaches of the River Dyje
Lusk, Stanislav ; Halačka, Karel ; Lusková, Věra ; Horák, Václav
The hydroeconomical modifications during 1968-1986 have changed fundamentally the natural hydrological regime of the lower Dyje River and adjacted floodplain. The proper stream channel was straightened and erected flood-oreventing leeves stopped natural floodings over the original floodplain substantial part. Elaborated and successively realised were specific rehabilitation projects that should eliminate negative impact of the modifications performed on the fish biota there. Concerned in the rehabilitation of the longitudinal and lateral migration permeability of the respective hydrological system for fish. That means to achieve the increase of aquatic habitat diversity by revitalisation of vanishing or by creation of new beckwater, pools and lagoons. The controlled inundation over a part of alluvial meadows has improved conditions for reproduction of phytophilous fish species. The rehabilitation of permanent connection in oxbows cut off (original river meanders) with the Dyje River will increase significantly the diversity of hydrological and geomorphological characteristics of the river bed channelised. The final goal is to create conditions for the ichthyofauna stabilisation and development in the respective area.
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