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Fishes as important indicators of environmental quality in the upper sections of the Tichá Orlice and Divoká Orlice rivers
Lusk, Stanislav ; Lusková, Věra ; Korunová, Vlasta
Investigations, implemented in the river network of the "Orlice" region over the past twenty years, made it possible to obtain data on the fish communities inhabiting the Tichá Orlice and Divoká Orlice rivers. The rivers are inhabited by salmonid fish communities dominated by Salmo trutta, Thymallus thymallus, Cottus gobio, and Lampetra fluviatilis. Water pollution was gradually limited by building water treatment plants as well as by the significant decrease in the intensity of agricultural activities. The environmental pollution with mercury in the Králíky region, lying on the upper reaches of the Tichá Orlice River, is a specific problem. Nevertheless, the mercury content in fish muscles has exceeded the hygienic limit (0.1 mg.kg-1). Fishermen consuming fish angled in the Tichá Orlice River have shown increased mercury contents in their hair.
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The fish ladder on the Dyje river at Bulhary: the first year of operation
Klíma, Ondřej ; Lusk, Stanislav ; Lusková, Věra
In the autumn of 2007 a fish ladder started operating on the river Dyje near Bulhary (river km 39.9). It is a near-natural fish ladder of the "bypass" type. The bypass is 210 m in length, its longitudinal slope is 1 : 56, there are 29 rock bars, the difference in water levels above and below a bar being 0.1 m, and the water discharge is round 2 m3.s-1. The function of the bypass was monitored throughout 2008. In all, 25 fish species were ascertained, indicating perfect permeability of the bypass. The occurrence of Leuciscus cephalus, Chondrostoma nasus, Barbus barbus and Alburnus alburnus in the bypass was connected with their marked spawning migrations. Some of the L. cephalus and B. barbus staed in the bypass for long periods, as indicated by the presence of marked individuals. In that locality, the function of the bypass is affected by water discharge, those exceeding 50 m3.s-1 increasing the water level below the weir, the water filling the lower part of the bypass.
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The round goby, a new alien species found in the confluence of the Morava and Dyje Rivers (Czech Republic)
Lusk, Stanislav ; Bartoňová, Eva ; Lusková, Věra ; Klíma, Ondřej
In 2008, the occurrence of the Round Goby (Neogobius melanostomus) was ascertained in the confluence area of the Morava and Dyje Rivers. This non-native species invaded the hydrographic network of the Czech Republic through its own migration activity from the Danube. In 2009, the species is already common in that area. Successful reproduction of this species has been evidenced by the occurrence of yearlings. Genetic analyses of mitochondrial gene cytochrome b ascertained high proximity hereof gene among populations from the Dyje and Dnieper Rivers. One haplotype only has been identified in the Dyje River which was as compared with the studies of Doherty et al. (1996) and Stepien & Tumeo (2006), closest to haplotype A. Analysis of the first intron of ribosomal protein has revealed five haplotypes, AM1 – AM5. The haplotypes AM1 – AM4 formed a separate group with haplotype AHC3 (Neilson & Stepien 2009) from the region of the Dnieper River near Kiev.
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The latest findings concerning the species diversity of gudgeon of the genera Gobio and Romanogobio in the territory of the Czech Republic and Slovakia
Mendel, Jan ; Lusk, Stanislav ; Lusková, Věra ; Koščo, J. ; Vetešník, Lukáš ; Halačka, Karel
During last 15 years the taxonomy of gudgeon have undergone extensive changes. The findings important for preservation of ichthyofauna of the Czech Republic and Slovakia include confirmation of generic differentiation of the original genus Gobio into two genera Gobio and Romanogobio. On the basis of genetic analyses, the originally accepted uniform structure of the species Gobio gobio was divided into the structures which can be assigned the level of species (G. gobio, G. obtusirostris, G. carpathicus, Gobio sp.). The original R. albipinnatus can be divided into the species R. vladykovi and R. belingi. The original species R. kesslerii can be divided into R. banaticus and apparently also Romanogobio sp. With regard to newly acquired knowledge it is necessary to revise the system of efficient preservation of the biodiversity found in the above mentioned taxa. The areas of sympatric occurrence of some species were localized and hybridization within both the genera was demonstrated.
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Ploidy and sexual status of the "Carassius auratus" complex in the waters of the Czech Republic
Lusková, Věra ; Lusk, Stanislav ; Halačka, Karel ; Vetešník, Lukáš ; Papoušek, Ivo
The "Carassius auratus" complex, non-indigenous in the Czech Republic, comprises several forms: C. a. auratus (decorative form), C. a. gibelio (predominant), and C. a. langsdorfii (Japanese form). C. a. gibelio is considered a "non-indigenous invasive species". Around 1975, the form invaded the waters of the Czech Republic from the Danube drainage area. The first invasive individuals were triploid females reproducing gynogenetically. The first males occurred in the Dyje River drainage area after 1990 and began transforming to a mixed type, both the sexual and ploidy status of C. a. gibelio populations changing. At present, the overall percentage representation of males in C. a. gibelio populations varies around 30 %, most of them being diploids, triploids occurring only occasionally. A larger part (60 %) of the females, which still predominate in the population, are triploids, the rest being diploids. Tetraploid individuals of both sexes occur quite singly.
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Renewal of migration permeability in the fragmented river network of the Morava River drainage area
Lusk, Stanislav ; Lusková, Věra ; Klíma, Ondřej
The migration permeability of weirs for fishes is considered one of the strategic revitalisation measures which can significantly contribute to the restoration and stabilisation of fish biodiversity. It is inevitable to define priorities for the preparation and realisation of successive steps in this respect. In principle, the migration permeability should be renewed systematically, starting from the lowest lying migration barriers and proceeding upstream. Highest priority should be given to measures and constructions that are vital in renewing the occurrence and dispersion of native and mostly protected and rare species (Zingel zingel, Z. streber, Pelecus cultratus, Gymnocephalus schraetser, G. baloni, among others). High priority should be given to fish ladders which permit reproduction migrations (Chondrostoma nasus, Leuciscus idus, Lota lota, Vimba vimba, etc.), in which this is an important part of biology, and the condition of restoring stability of their populations.
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Factors affecting the species composition of fish communities inhabiting sections of the rivers Morava, Dyje, Odra and Lužnice and their adjacent floodplains
Lusk, Stanislav ; Lusková, Věra ; Lojkásek, B. ; Hartvich, P.
The species composition of fish communities was studied in sections of the rivers Morava and Dyje (Black S. basin), Odra (Baltic S.), Lužnice (North S.) with floodplains. The following factors appear to determine the species composition of the ichthyofaunae inhabiting the hydrological regions: Sea basin, location of the section in the longitudinal profile of a stream, absence of migration barriers, presence of fishponds, fishery management. As regards the origin of a community, the pertinence to a basin is of greatest importance and migration from the lower sections. As regards the species richness of ichthyofauna, the region of confluence of the rivers Morava and Dyje is the richest of the whole Czech Republic - 38 native species, 9 of which occur only in that region, 7 alien species was recorded in that region. The region of the Odra R. was found to harbour 29 native and 4 non-native species; that of the Lužnice R., 25 native and 5 non-native fish species and 1 lamprey species .
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