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Ichthyofauna of the lower reaches of the Dyje River and the adjacent floodplain with floodplain forests
Lusk, Stanislav ; Lusková, Věra ; Halačka, Karel ; Horák, Václav ; Pražák, O.
The lower reaches of the Dyje River with adjacent floodplain constitute an unique territory fragment in the Czech Republic. Its hydrological system is prominent with a high diversity of aquatic habitats including natural floodings over the floodplain part. During last 50 years, the occurrence of 49 species fish was found there in total. Of them, 41 species are assessed to be autochtonous, i.e. 75% of the native ichthyofauna structure of the Czech Republic. As strategically significant, the direct barrier-free connection of the lower Dyje River through the Morava River with the Danube has been manifested. In such way during recent years, the occurrence has been renewed of naturally immigrating Pelecus cultratus, Gymnocephalus schraetser and Zingel zingel, which had disappeared in the past. Sporadically, also the occurrence of Acipenser ruthenus and the wild form Cyprinus carpio is renewed. Naturally in the territory of the Czech Republic, new species such as Carassius auratus, Proterorhinus marmoratus, Sander volgense and Gymnocephalus baloni have penetrated. This unique territory is intended to be proclaimed for the Biospherical reserve and as protected territory for selected fish species within the NATURA 2000 system.
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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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Fish assemblages of the artificially made water habitats in floodplain forests
Horák, Václav
In the alluvium of the Dyje River (r. kms 0.0-35.00) the original biotops and the artificially made biotops (created as a part of revitalisation activities) were studied in two floodplain forest complexes (the Kančí obora and the Soutok floodplain forests). Within the Kančí obora floodplain forest the most diversified assemblage was found in the new made complex of three pools, the Palachy (16 species) because of its permanent connection with hydrological systém. The species Rutilus rutilus, Scardinius erythrophthalmus, Blicca bjoerkna occured most. In the original pool U svaleného dubu (14 species) were the R. rutilus, S. erythrophthalmus species most frequent. Within the Soutok area in the artificially made complex of two pools, the Kesle, 9 fish species were found. The species Abramis ballerus occured most. In the original pool, the Krumpava, 10 fish species were found with A. ballerus occuring most as well. The artificially made habitats (pools) provide the same conditions for fish if permanently connected with the hydrological system of the floodplain forest.
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