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Chironomid communities of the Upper Stropnice River (Novohradské Mountains, South Bohemia)
Chalupová, Š. ; Matěna, Josef
The communities of chironomid larvae of the Upper Stropnice River were studied semiquantitatively between the river kilometres 40-55 during 2000 and 2001. Altogether 29 taxa were observed. Dominant forms were .i.Apsectrotanypus trifascipennis./i., .i.Macropelopia nebulosa./i. and .i.Prodiamesa olivacea./i.. The water quality calculated according to the chironomid communities corresponds to beta-mesosaprobity, only in the area of Upper Stropnice village it deteriorates to alfa-mesosaprobity. This fact gives evidence to presence of point sources of organic pollution. Further downstreams the values of saprobity return to the state above the source of organic pollution. In the anthropically influenced area of the stream the decrease in the diversity of chironomid communities occured. It is necessary to consider the results as preliminary, because the only family Chironomidae was analysed in detail, for exact results the analysis of the whole macrobenthic community is necessary.
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The diet of larval and juvenile pikeperch (.i.Stizostedion lucioperca./i.)(L.)), comparative study of fishponds and a reservoir
Peterka, Jiří ; Matěna, Josef ; Lipka, J.
Diet of larval and juvenile pikeperch (.i.S. lucioperca./i.) reared in ponds was investigated and compared with the diet of pikeperch from a reservoir. Numbers of rotifers were found low in the diet of pikeperch larvae in fishponds and they were soonreplaced by nauplii of cyclopoid copepods. .i.Daphnia./i. spp. were consumed from the onset of exogenous feeding. Another smaller cladoceran .i.Bosmina./i. longirostris did not contribute to the diet significantly. In the reservoir, rotifers were not found in the diet of pikeperch larvae. Dominant food items were nauplii and 1st copepodite instar of .i.Eudiaptomus gracilis./i. and .i.Cyclops./i. spp. .i.Daphnia galeata./i. and to a lesser extent .i.Diaphanosoma brachyurum./i. appeared in the pikeperch diet at a length of about 10 mm. A shift towards larger prey, especially .i.Leptodora kindtii./i., could be recognised in pikeperch at a length of 20 mm. Growth of pikeperch was found faster in nursing ponds than in the reservoir.
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Diel fluctuation of fish catches taken by pelagic gillnets in the Římov Reservoir
Vašek, M. ; Čech, M. ; Draštík, V. ; Dušek, D. ; Hladík, M. ; Kubečka, Jan ; Matěna, Josef ; Peterka, J. ; Pokorný, P. ; Prchalová, M. ; Štafa, P.
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