|
|
Non-indigenous freshwater fish species of the Mediterranean basin of the Balkans
Balog, Štefan ; Vukićová, Jasna (advisor) ; Švátora, Miroslav (referee)
Mediterranean basin of the Balkan Peninsula is one of the hot-spots of biodiversity, with a high diversity of freshwater fishes and high degree of endemism. Introduction of non-native species greatly affects ecosystems and native species of fish. There were many reasons for introductions in the past. Aquaculture, sport fishing and ornamental fish belong to the most important reasons for introduction of non-native fish species. Altogether, 39 species belonging to 12 families were introduced in the Mediterranean basin of the Balkan Peninsula. Most of them belong to the families Cyprinidae and Salmonidae. Introduction of fishes was known since the Roman era. Although the first recorded introduction in this area was in the 13th century, most species were introduced in 20th century. The fishes were introduced from North America, Europe and Asia. Many translocations occurred in this area, too. Translocation is a relocation of particular species within one area. The most widespread introduced species in the Mediterranean basin of the Balkans are common carp (Cyprinus carpio), stone moroko (Pseudorasbora parva), rainbow trout (Onchorhynchus mykiss), mosquitofish (Gambusia holbrooki), goldfish (Carassius auratus) and sunfish (Lepomis gibbosus). Hybridization, competition, pathogen transmission and predation...
|
|
|
Methods of study habitats and microhabitats preferences of freshwater fishes of Central Europe
Žák, Jakub ; Švátora, Miroslav (advisor) ; Drozd, Bořek (referee)
Small streams are a common habitat in Central Europe with unstable, rapidly-changing conditions. We can examine habitats on three different scales: microhabitat, mesohabitat and macrohabitat. Habitat preferences were among the fields of interest of Antonín Frič as he tried to describe the changing gradient of fish assemblages from source to the river's mouth on the macrohabitat scale. Habitat preferences are examined from a spatial point of view (substrate, depth, shelter), temporal point of view (season, day/night), biotic point of view (interspecies and intraspecies competition) and abiotic point of view (dissolved chemicals, velocity). For obtaining data of good quality, it is necessary to choose the right location and select the opti- mal strategy of examining fish assemblages (e.g. electrofishing, radiotelemetry, cameras). All variables which can affect habitat preferences in fish are measured. Multivariate statistical methods (e.g. PCA, RDA, CCA, CA) are used for evaluation of obtained datasets. Currently, we live in a fast developing period of this scientific area because of the need of evaluation of the human impact on freshwater biotope. The aim of this bachelor thesis is to introduce variables which influence habitat pref- erences of fish, to propose a modern review of methods commonly...
|
|
|
Population dynamics of Asp Leuciscus aspius from the Želivka dam
Bouše, Eduard ; Švátora, Miroslav (advisor) ; Pivnička, Karel (referee)
The aim of this study was to evaluate the material about the asp Leuciscus aspius (L., 1758) from the dam Želivka - Švihov in the years 1971 - 2014. Main emphasis was put on the analysis of the flock spawning from 2008 - 2014. Here, basic abiotic conditions were monitored at the time of the spawning and growth and population characteristics were calculated. Spawning took place at two locations, at 4 - 10 0 C, the asp showed a spawning site accuracy. Males predominated on the spawning grounds in the overall ratio of 1,22 : 1. The age of the fish examined ranged from 3+ to 13+. The average mortality of adults is about 0,4. Additional flock spawning ranges from 20 to 50%. The length at which scales begin to form (SL = 29,7 mm), was determined by using the rate between the body length and scale radius. Differences in the growth rates between males a females are minimal, only from the third to the fifth age group, males showed a higher growth rates. The length - weight relationship can be described as W = 0,0153. L3,19 .
|
|
|
Population dynamics of Asp Leuciscus aspius ( L., 1758) from the Želivka dam
Bouše, Eduard ; Švátora, Miroslav (advisor) ; Pivnička, Karel (referee)
The scale material of the asp (Leuciscus aspius, L., 1758) collected from the Želivka dam between 1971 and 2012 has been processed and evaluated. The samples gathered between 2008 and 2012 have been used to determine the basic growth and population characteristics. In the first place I focused on the shoal spawning analysis. The age of individuals in this analysis ranged between 3+ to 13+, at the body length ranging between 370 to 690 mm. The length of the fish when the scales begin to appear (SL = 29,7 mm) was determined on the base of correlation between the body length and the scale radius. The growth rate in recent years was defined using the technique of back - calculation from the scales. The body length-weight relationship can be described as W = 0,009 ∙ L3,1 . The difference in the growth speed between males and females was minimal and statistically inconclusive. The growth speed of an asp in the Želivka dam is roughly at the same level as all other water reservoirs in Czech Republic.
|
|
|
Phylogeography of the genus Squalius in Albania
Lerch, Zdeněk ; Švátora, Miroslav (advisor) ; Kalous, Lukáš (referee)
The thesis is focused on the issue of the Squalius genus phylogeography in Albania in the Balkan region. Phylogenetic analyses of sequence variation at mitochondrial genes (cytochrome b) were used to examine these issues for the freshwater fish genus Squalius from various river systems in the Adriatic Sea region. There were identified 3 genetic lineages of vague taxonomic position where the genetic variation amount to 1.6-2.1 %. The first lineage is distributed in north of Albania and in the whole Periadriatic region, the second lineage is especially spread to northern part of Albania and the third lineage covers especially the zone of the European ancient lake systems on the Balkan Peninsula (Lake Ohrid and Prespa), from where expands to the southern part of Albania. There sympatrically coincide the both lineage in the hydrological river-lake system of Drin and Skadar. The phylogenetic and taxonomic position of the Squalius genus in the region seems to be interesting topic for subsequent and more detailed study. Keywords: Squalius, Albania, cytochrome b, phylogeography
|
|
| |
|
|
Distribution patterns and habitat requirements of the species of the family Cobitidae in Slovakia
Pekárik, Ladislav ; Švátora, Miroslav (advisor) ; Ráb, Petr (referee) ; Matěna, Josef (referee)
Distribution patterns and major environmental correlations of the species of the family Cobitidae are presented here. All three species are still relativem widely distributed in Slovakia. Comparing with the past, no rapid ganges have been found. However, river regulation, pollution and the lowland amelioration affected the distribution of these species. Following the results of the occurrence of Balkan spined loach (Sabanejewia balcanica) within the mesohabitat scale, distance from source, slope, water depth and vegetation cover are the most influential variables in the proposed model. All these variables that contribute to our model explanation determine the stream morphology that affects the consequences of local temperature conditions and other abiotic factors as oxygen amount. Switching to microhabitat spatial scale, several microhabitat variables significantly influence the spatial distribution of analysed species. Depth more than 40 cm, refuges stones and point near bank (<15% of river width) are the most influential ones supplemented with substratum sand, substratum cobbles, substratum boulders, no refuges, refuges woody, depth 0-10 cm and maximum velocity none. Balkan spined loach occurs in the microhabitats occupied also by young-of-the-year (YOY) individuals and common minnow (Phoxinus...
|
|
|
The effect of selected parameters of stream water on gill morphology of brook charr and the structure of ichthyofauna of the Jizera Mountains
Hušek, Jiří ; Dušek, Martin (referee) ; Švátora, Miroslav (advisor)
The occurrence of ichthyofauna on the territory of the Jizera Mountains (Northern Bohemia, Czech Republic) is limited, besides other factors, by the water chemistry. pH value and pH-related concentration of inorganic monomeric aluminum (Ali) are crucial parameters of the water, determining the survival of fish in streams. Low pH and high concentrations of Ali cause severe damages to fish gills. The thesis deals with the influence of the water chemistry on distribution of ichthyofauna in the Jizera Mts and gill morphology in brook charr (Salvelinus fontinalis), a dominant fish species of the upper plateau of the mountains. The results show that the species diversity of fish in acidified streams is lower than that in streams without meaningful acidic episodes. Histopathological analyses of gills of brook charr individuals from an acidified stream confirm, that low pH values and high concentrations of Ali have a cummulative effect and lead to degenerative changes on gills. Key words: The Jizera Mountains, ichthyofauna, brook charr, gill morphology, water chemistry, toxic aluminium, acidification
|
|
|
Influence of environmental factors on fish assemblages in streams of the Elbe and Oder basins
Kůra, Luboš ; Švátora, Miroslav (advisor) ; Matěna, Josef (referee)
ABSTRACT The effects of environmental parameters on changes in the structure of fish assemblages were studied in the Elbe and the Odra river basin. Research was done at 819 sites that were surveyed in the field during the period between 1993 and 2007. The impact of 46 factors derived from the maps through a geographic information system was tested as well as the impact of 10 factors recognized in the field. To evaluate the influence of these factors the indirect (Detrended Correspondence Analysis, DCA) and direct (Canonical Correspondence Analysis, CCA) multivariate cluster analysis were used. Analyses were performed with data on presence-absence and relative abundance of each species. DCA well reflects changes in assemblages in the longitudinal profile of streams. CCA refers to a significant influence of regional and temporal variability and influence of individual factors. The fish assemblages are best characterized by the analyzed factors of distance from the source location, stream slope, altitude of locality, representation of arable land in the basin, number of ponds in the sub-basin above the locality, type of waters (salmonid or cyprinid), and water temperature (the only of the parameters of the field). The analyzed factors better reflect the variability in fish assemblages of the Odra...
|
|
| |
guest ::
RSS feed.