Altogether 71 samples collected in 1968–2004 from the Rokytná and Loučka rivers were used to estimate proportional fish species richness from single-pass electro-fishing and probabilities of detection for individual fish species. Mean estimated species richness from single-pass sampling (p ́s1) was 95.4% and 96.2% of estimated total species richness for Rokytná and Loučka rivers, respectively. However, p ́s1 values for individual sites ranged from 71.4% to 100% of estimated total species richness. Additional species unique to the second pass were collected in 38% (Rokytná) and 22% (Loučka) of the samples. When assessing the fish assemblage structure by a multivariate technique (PCA), considerable inaccuracy between the single-pass and two-pass electro-fishing data was also observed. Decisions regarding standardized sampling effort and whether to conduct one or more electro-fishing passes must be based on study objectives. For more accurate evaluations of fish assemblage structure two-pass electro-fishing is recommended. Three-pass electro-fishing did not produce significant increase of species richness.
The Amur sleeper, Perccottus glenii Dybowski, 1877, is indigenous in eastern Asia. During the second half of the 20th century, with the aid of man, it spread over the eastern part of Europe as well as in central Asia. In the course of 50 years of its dispersal in the western direction the species already reached the Vistula drainage area (the Baltic Sea basin) and the Danube drainage area (the Black Sea basin). In the latter basin, its occurrence was ascertained in the drainage area of the Tisza river in Hungary in 1997. In eastern Slovakia, the Amur sleeper was first recorded in 1998 in the Latorica drainage area. In the course of subsequent years it has become a common species in the streams in the basins of the Latorica, Bodrog and Tisza rivers. In shallow lentic waters densely grown with aquatic plants the species becomes a superdominant or even exclusive species in the local fish communities. It has no marketable value but presents a serious threat to the existence of native fish species with similar identical microhabitat requirements.
The common gudgeon Gobio gobio (L.) has a great phenotypic plasticity being one of the most variable fish species in Europe. In the Iberian Peninsula it has been considered to be an introduced species. However, recent publications have considered that gudgeon populations from different basins of the Iberian Peninsula are native. in this work we tried to clarify the status of Iberian populations by means of molecular methods. thirty-two specimens of common gudgeon from several localities placed in six different Iberian and South French basins (Duero, Ebro, Tajo, Nansa, Bidasoa and Nivelle) were analysed. We reconstructed the phylogenetic relationships between the Iberian gudgeon populations using the whole cytochrome b gene sequence (1141 bp). Moreover, one specimen of G. gobio from the Danube basin and two specimens of Ramanogobio (R. ciscaucasicus and R. uranoscopus) were also included in the study. Our data confirmed the monophyly of the Iberian-French populations analysed and indicated a high genetic differentiation with respect to the common gudgeon populations from Central Europe. However, our results also indicated a very close genetic relationship among the populations of different Iberian basins, showing low genetic distances between them. The absence of population structure among the Iberian populations of G. gobio seems to be due to human activity.
Seven populations (Oľšava/Hornád R., Oľšava/Topľa R., Ublianka R., Ondava R., Ipeľ R., Malý Dunaj R. and Vlára R.) of Balcan spined loach were subjected to phylogenetic analysis based on variability of the cytochrome b gene and mitochondrial specific marker. They were separated in to five groups but these groups were represented by specimens from different populations. Genetic distances among populations and among groups were quite low. Subsequently, analysis of relations among our groups and sublineages of Danubian-Balkanian complex of Sabanejewia was made. the first four groups were genetically close to sublineage III, while the fifth one to the sublineage IV. These findings agree with the conclusion about conspecificity of analysed Danubian-Dniester populations belonged to monotypic S. balcanica. Phylogenetic analysis showed that the most suitable populations for the restoration of this species in the Bečva River are populations dwelling the Ipeľ and Vlára rivers.
Genetic diversity of three pure populations of Cobitis elongatoides from hydrologically and geographically different drainage areas, the Lužnice River (48.49.60 N, 14.55.60 E, Labe River drainage area, North Sea basin), the Nová Říše reservoir (49.09.11 N, 15.32.464 E, Morava River drainage area, Black Sea basin), and the Ida River (48.32.284 N, 21.03.421 E, Tisza River drainage area, Black Sea basin) was evaluated by sequencing of mitochondrial cytochrome b gene. Species identification of unknown Cobitis samples from Vipava River drainage area in Slovenia was also performed based on cytochrome b sequence. All forms of the genus Cobitis are protected by national legislatives and, in accordance with the Council Directive No. 925/43/EEC, they enjoy protection in selected localities of European importance. In total, 11 haplotypes of Cobitis elongatoides were found in Czech and Slovak waters, manifesting low overall genetic diversity. Samples from Vipava River drainage area were identified as Cobitis bilineata.
The random amplified polymorphic DNA (RAPD) method was applied to eight Gobio gobio populations living in the rivers of the Czech Republic and Slovakia. The application of seven RAPD primers yielded eight fingerprint characteristics for the populations examined. Forty diagnostic markers have been identified, which can reliably identify the populations under study. Intrapopulation diversity varied between 0.26 and 0.38. A phenogram documented the close agreement of the particular populations with the geographic pertinence of their localities to the different sea basins.
Monitoring of the analysed populations of the endangered fish species Misgurnus fossilis was conducted using microsatellite analysis and sequencing of a part of the control region. Absolutely first microsatellite markers for weather loach were found. Six polymorphic microsatellite loci were prepared, five of which were tested. Number of alleles per a locus ranged from 3 to 5. All studied populations are differentiated one from another (FST= 0.205 - 0.367). All sampled populations contained unique alleles. Sequential analysis of the mitochondrial control region showed great haplotype similarity of the studied populations which come from one widely spread haplotype H_1, and thus suggested possible hypothesis of recent spreading from one source.
Sample of Gobio gobio from 30 localities in the Czech Republic and Slovak Republic were studied. Starch gel electrophoresis was used for evaluation of variability of allozyme patterns in 16 active protein systems comprising 26 loci. Products of 17 loci were considered to study the genetic structure of its populations. From this, genetic variability was found in ten loci, occurrence of rare alleles was detected in next four loci. Percentage of polymorphic loci ranged between 6 and 41%; mean occurrence of alleles was between 1.1 and 2.0 per locus; and mean heterozygosity was observed at 0.013 to 0.248. The genetic distances among populations were 0.002 to 0.175 (N e i 1972) and 0.063 to 0.385 (C a v a l l i - S f o r z a & E d w a r d s 1967). Differences in occurrence and frequencies of alleles in some loci among the sea basins were evident. Higher genetic variability identified in populations from the Danube river system (Black See basin) is probably connected with the fact that this basin served as a refuge for ichthyofauna during glaciations.
The actual distribution of gudgeons native to the River Kuban (Gobio sp., Romanogobio pentatrichus, R. parvus) is described based upon new taxonomic conclusions and reliable species identifications. Numerous new materials were collected during several expeditions by the authors in 2001-2003 to the Northern Caucasus, Western Transcaucasia, Voga, Kuban, Don and other rivers of the Sea of Azov and were re-examined from collections of the Zoological Institute (St. Petersburg, Russia) and the Chair of Zoology of Kalmykia State University (Elista, Russia).