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The dynamics of sexual reproduction and ephippia production of Daphnia in reservoirs
VANÍČKOVÁ, Ivana
This thesis focused on the dynamics of the sexual reproduction of microcrustacean Daphnia (Cladocera, Anomopoda). Sex in Daphnia is induced environmentally after rounds of asexual parthenogenesis in favorable conditions. The onset of sexual reproduction and the occurrence of sexual individuals was investigated with respect to their distribution in the water column and clonal structure. The produced sexual eggs were genotyped and their density and distribution in sediment were analyzed. The impact of massive floods was investigated. The role of sexual reproduction in stable habitats and its relevance and importance for Daphnia communities is further discussed.
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Dynamics of fish spatial distribution in reservoirs
ŘÍHA, Milan
This dissertation thesis focuses on several aspects of fish ecology in reservoirs and the methodology of their sampling. It is divided to three parts. The first part focuses on the dynamics of fish distribution throughout the seasons and between day and night. The second part deals with the efficiency and the selectivity of the beach seine net, trawl and purse seine net. The third part describes the long-term development of fish populations in the Římov Reservoir.
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Ecological demands of the selected planktonic algae and cyanobacteria from the order Nostocales. Light intensity and temperature optima of the water-bloom dominant species in the ponds and reservoir in the Czech Republic.
KOHELOVÁ, Hana
This thesis is aimed on cyanobacterial water blooms. It deals with the composition of cyanobacterial water blooms, factors which cause its emergence, effect it has on environment, termination of cyanobacterial bloom and ways of how to restrict it. My thesis contains the chapter devoted to the cyanobacterial bloom characteristic, which gives them advantage over other organisms in plankton and over other cyanobacteria as well. It also contains general description of fishponds and reservoirs and locality description (fishpond Svět and Rod, water reservoir Římov, Jihočeský kraj), which were the sources of species tested in this experiment. The aim of the experiment was to find out the optimal temperatures and light for the growth of seven strains of cyanobacteria and one species of green alga. The experiment was conducted by cross-table gradient of temperature and light method (KVÍDEROVÁ a LUKAVSKÝ, 2001. Data of the strains growth in different combinations of temperature and light intensity was processed in program Statistika (ANONIMUS, 1996). Valence of each strain has its maximum and minimum values. In their mean, there is an optimum for the growth. Charts depicting maximal-minimal values and optimum of strains for temperature and light were created in Microsoft Excel. Details between temperature and light demand of strains were tested by PCA analysis in program CANOCO 4.5 and visualised by CANODRAW (TER BRAAK a ŠMILAUER, 1998). It resulted in particular values, which are comparable with similar laboratory tests.
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The morphological and genetic differentiation of \kur{Daphnia} in canyon-shaped reservoirs
HOROVÁ, Barbora
We analysed the pattern of spatial heterogeneity of Daphnia longispina species complex in 11 canyon-shaped reservoirs. We found for the first time that the spatial pattern is not random. Daphnia cucullata shows strong preference for upstream regions while Daphnia longispina and D. galeata x longispina are preferring the deep downstream parts of reservoirs. These not random pattern is probably driven by longitudinal and vertical ecological gradients (fish predation pressure, nutrient concentration, phytoplankton biomass etc.)
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Sampling of the offshore fry fish communities of reservoirs by trawls
Jůza, Tomáš ; Kubečka, Jan ; Čech, Martin ; Draštík, Vladislav ; Jarolím, Oldřich ; Peterka, Jiří ; Vašek, Mojmír
The offshore area of six Czech reservoirs was sampled by pelagic fry trawl in late summer in 2003-2005. In Římov, Želivka, Vrané and Slapy reservoirs cyprinids dominated in offshore area. The main species here were roach, bream and bleak. In Lipno and Nýrsko reservoirs percids dominated in offshore area (Lipno-pikeperch, Nýrsko-perch). Trawling in offshore areas revealed that almost all 0+ fish were caught in the surface stratum (0-3m depth). In reservoirs where percids and cyprinids occured together, cyprinids dominated in 0-3m depth while percids usually prevailed in catches of 0+ fish from 3-6m depth. In ordinary canyon-shaped reservoir like Římov and Želivka the 0+ fish abundance decreased from the upstream end toward the dam, so the biggest abundance was in tributary area. In cascade reservoirs like Slapy and Vrané, the offshore area in tributary is almost without fish. The peak of abundance is more downstream and from this place, the trend is similiar to non-cascade reservoirs.
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Flood situations influence on water quality in reservoirs controlled by means of mathematical modelling
Kafková, Dagmar ; Balejová, Marcela
Příspěvek se zabývá možnostmi matematického modelování pro sledování vývoje kvality vody v nádržích za běžných provozních podmínek i během extrémních povodňových situací se zvláštním zreželem na nádrž Pastviny na Divoké Orlici. Pro tuto nádrž byl upraven dvourozměrný matematický model CE-QUAL-W2, který se již dříve osvědčil při modelování nádrže Římov na Malši. Validaci modelu pro nádrž Pastviny nelze v současné době považovat za dokončenou, protože z předchozích let není k dispozici dostatečné množství bilogických a chemických dat, avšak bathymetrická data již odpovídají současnému stavu po vypuštění a vyčištění nádrže a model je připraven pro použití, jakmile budou potřebná data shromážděna.
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