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Investigation of Cladophora sp. distribution in the Brno reservoir, conducted under the project “The implementation of management measures at the Brno reservoir, phase II 2013-2017
Borovec, Jakub ; Matějíčková, Ivana ; Vejřík, Lukáš ; Kočvara, Luboš ; Hauer, T.
The occurrence of the green alga Cladophora and other macrophytes in the Brno reservoir was confirmed. The distribution of Cladophora stands was assessed as not dramatic, despite of the temporary occurrence of a mass of surface-floating filaments. This increase in buoyancy of the Cladophora colonies was caused by excessive oxygen production in the co-growing algal species (Tetraspora sp.).
Research on reproductive biology of asp Leuciscus aspius and its sampling during 2008 and 2014 in Švihov reservoir
Vejřík, Lukáš ; Bouše, Eduard ; Matějíčková, Ivana ; Ricard, Daniel ; Kubečka, Jan
Based on electrofishing for asp in main tributaries of Švihov reservoir and subsequent tagging of captured fish, size and age composition of asp spawning stock together with the importance of primary and secondary tributaries for spawning and asp growth was evaluated in years 2013 and 2014. Survival of fish tagged in previous years 2008-2012 was estimated as well.
Hydrobiological monitoring of Medard lake in 2011
Kubečka, Jan ; Blabolil, Petr ; Borovec, Jakub ; Čech, Martin ; Draštík, Vladislav ; Hejzlar, Josef ; Nedoma, Jiří ; Peterka, Jiří ; Prachař, Zdeněk ; Rychtecký, Pavel ; Seďa, Jaromír ; Vejřík, Lukáš ; Znachor, Petr
The report summarizes results of research on limnological components of lake Medard (former opencast mine Medard-Libík) achieved in 2011, and suggests recommendations for further monitoring of the lake.
What do the fish say about the quality of aquatic ecosystems
Blabolil, Petr ; Říha, Milan ; Peterka, Jiří ; Prchalová, Marie ; Vašek, Mojmír ; Jůza, Tomáš ; Čech, Martin ; Draštík, Vladislav ; Kratochvíl, Michal ; Muška, Milan ; Tušer, Michal ; Frouzová, Jaroslava ; Ricard, Daniel ; Mrkvička, Tomáš ; Sajdlová, Zuzana ; Vejřík, Lukáš ; Šmejkal, Marek ; Borovec, Jakub ; Matěna, Josef ; Boukal S., David ; Kubečka, Jan
The first Czech methodology for the assessment of ecological potential of heavily modified water bodies and artificial water bodies based on fish communities was developed. The first step of developing the methodology was preparing the typology of water bodies. The typology distinguishes between water bodies of different altitudes and with and without thermal stratification. Fish were sampled by multimesh gillnets following European standard procedures. The selection of fish metrics was based on statistical analyses in which metrics (fish community indicators) were correlated with the most common stressor – eutrophication. The analysis detected several sensitive metrics (metrics showing the best correlation with the stressor) in which ecological class boundaries were set. Afterwards, combination of sensitive metrics was used for calculation of the ecological quality ratio (EQR) for each of the reservoir sampled. The EQR expresses the deviation between a reservoir’s current ecological status and its maximum potential. The next step consisted of validating the EQR with an independent pressure index and verifying the time stability of ecological potential assessment. The metrics used in the methodology fulfill all the obligations set forth in the Water Framework Directive (2000/60/EC), which include assessment of the composition, abundance and age structure of fish fauna.
Redundant fingerling of perch (Perca fluviatilis L.) in Vír Reservoir and its impact on other trophic levels
VEJŘÍK, Lukáš
The composition and preferences of depth levels and habitats of pelagic fingerling was studied in the canyon-shaped Vír Reservoir during years 2009-2011. The perch (Perca fluviatilis) fingerling was dominant in all three years. The density of fingerling was above the mean in years 2009 and 2010. It was as many as 278 individuals in 100m3(mean is 52 individuals in 100m3). A marked fall on 1,9 individual in 100m3 was registered in 2011. Perch fingerling was mainly observed in metalimnion during the day and also at night, where concentration of oxygen was very low. The highest density of perch fingerling was observed in the middle part within longitudinal profile. A significant difference was found in food composition among the years with high density and low density of fingerling. A predation of carp (Cyprinus carpio) and bream (Abramis brama) was proved during the years with high density of fingerling.
Food, growth, sex ratio and depth distribution of perch \kur{(Perca fluviatilis L.)} in newly created lakes in Podkrušnohoří
VEJŘÍK, Lukáš
Food, growth, sex ratio and depth distribution of perch (Perca fluviatilis L.) were studied in Milada Lake, Most Lake and Barbora Lake. These lakes were artificialy created after a coal mining. Sex ratio and depth distribution were also compared with data gathered from Vír Reservoir and Římov Reservoir. Fish designed for the research were captured by gillnets. Age analysis was carried out by otolite scanning. Food, growth and depth distribution were analysed with consideration of size and sex of the fish.

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7 VEJŘÍK, Lukáš
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