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The Occurrence and Basic Aspects of the Biology of Pseudorasbora parva (Temminck et Schlegel, 1842) in a Model Pond System located in the region of Třeboňsko
ČECH, Miroslav
The stone moroco (Pseudorasbora parva) is a invasive little fish whose species origin is not from our waters. It is desirable to eradicate this species from the Czech environment or at least decrease its numbers as much as possible, using an environmental method. The data for the dissertation was found out on a model pond system in Třeboňsko. This complex consists of thirteen ponds 203.1-hectare. The ponds in this locality are highly productive and their average depth is about one meter. The aim of the dissertation was to determine the composition of feed of Pseudorasbora parva and according to this, to assess the potential importance of this species as a rival to the locally bred carp (Cyprinus carpio). The other submission was to map the migration of Pseudorasbora parva in the aforementioned pond system and to determine what part of the pond is the most coveted by this fish and estimate the total number of fish population in some ponds. The use of fingerling nets was one of the methods used to catch Pseudorasbora parva in the shallow water of the ponds. Furthermore fish-pots were used for catching fish in the deeper parts, and drop nets were used for catching in the effluents. The Pseudorasbora parva was present for a whole calendar year in all parts of the system i.e. in all ponds, drains and in their effluents. The stone moroco occurred predominantly at the banks of the pond. The occurrence of fish in the open water was recorded sporadically. The sampling of plankton was carried out with plankton net in different seasons. With exception of winter when plankton was not found, the composition of feed the same during the whole year. Only proportional representation of species of plankton was different. The catching of Pseudorasbora parva was performed in the ponds Pražský, Rod, Láska and Víra, the fish was necropsied for assessment the intestine content. At the same time four carps of age group K2 were necropsied. By the analysis of the intestine content the conformity in the feed consummation by both aforementioned fish species was confirmed.
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Food of predatory fish during the flooding of the Chabařovice coal mining pit
KABILKA, Petr
The Chabařovice coal mining pit is currently still under the process of continuous flooding and its area increased up to 174 ha since 2001.Adult perch (Perca fluviatilis) have been the most numerous fish of the lake until 2004. Fish were collected during the ichtyological survey sampling campaigns in June and September.Diet composition was expressed as percent weight, which was calculated for each prey taxon.
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Distribution and expansion of planctic cyanobacteria in Czech Republic
Komárek, Jiří ; Komárková, Jaroslava
Planktic cyanobacteria play important role in freshwater habitats in Czech Republic. They develop sometimes in massive water blooms, produce cyanotoxins and must be monitored from hydrobiological and sanitary point of views. Frequency of their occurrence and the species composition change in time and depend on managing of water ecosystems and on global changes of climate. The distribution and occurrence of various species in Czech Republic over last 60 years is reviewed.
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Biodiversity of standing floodplain waters and processes of its formation and preservation
Pithart, David
Water chemistry and planktic communities in the naturally eutrophic alluvial waters in the Lužnice floodplain have been studied. The floofplain waters are naturally eutrophic, with strong vertical physico-chemical gradients and oxygen depletions at the botom. Small pools and backwaters of this type have unique phytoplankton structure. Prevailing dominance of flegellates, namely Cryptophyceae, and low proportion of green chlorococcal algae and Diatoms, and almost absence of Cyanophyceae are very unusual for such eutrophic waters. Flagellate dominate thanks their ability to keep the vertical position in a permanently light limited conditions (resulted from poorly mixed water columns and intensive shading of water surface by vegetation). Floodplain geodiversity play crucial role, determining morphology and location of pools and backwaters, their exposition to flooding and inflows of underground water. Terrestial vegetation effects light exposition, leaf litter.
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The effect of a high through-flow on the plankton of the reservoir Slapy?
Hrbáček, Jaroslav
In August 2003 an extraordinary intensive trough-flow has replaced the volume of water in the Slapy Reservoir in few days. Immediately a decrease of the transparency pH, frequency of planktonic crustaceans and an increase. In comparison with the previous years in the weeks following the flood an unusual increase of the frequency of blue greens mainly Microcystis and the diatoms Melosira a decrease of the diatom Fragillaria, and desmid Staurastrum was observed. As a possible cause decrease of pH and increase of total phosphorus has to be considered. As a possible cause of the decrease of the cladoceran Diaphanosoma and increase of species of Daphnia and Bosmina either the decrease of predation pressure by the export of fry due to the flood or the increase of food basis due to more intensive development of phytoplankton has to be considered. The effect of an exceptionally high through-flow on plankton is far from a dramatic one.
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Fytoplankton aluviálních tůní
Pithart, David ; Kylbergerová, Magdalena ; Pechar, Libor ; Hrbáček, Jaroslav ; Fiala, Dan ; Bílý, Michal ; Rulík, M.
Phytoplankton of alluvial pools at Lužnice alluvium have been investigated by following methodological approaches: seasonal course of phytoplankton in two pools, extensive sampling (quarterly) of 30 pools, and phytoplankton diurnal vertical migration studies in several pools. Prevailing dominance of phytoflagellates, especially Cryptophyceae and Euglenophyceae and low contribution of coccal forms as Chlorococcales and Cyanophyte has been found as a main feature of phytoplankton community. This is caused by poor mixing of water column (large relative depth, wind protectio), where th ecoccal forms sediment out and are outcompeted by motile forms, able to determinate the position within the water column.
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