|
|
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.
|
|
| |
|
| |
|
| |
|
| |
|
| |
|
|
Ovlivňuje obsah buněčných mastných kyselin a enzymů jeskynních bakterií potravní preferenci .i.Enchytraeus crypticus./i. (Oligochaeta, Enchytraeidae)?
Krištůfek, Václav ; Elhottová, Dana ; Šustr, Vladimír ; Lasák, R. ; Kováč, L. ; Mock, A. ; Luptáčik, P.
Cellular fatty acid screening (MIDI System) of 93 bacterial strains isolated from the Domica Cave in the Slovak Karst region ( Slovakia) showed that three bacterial strains (.i.Chryseobacterium./i. sp., .i.Enterobacter amnigenus, Rhodococcus./i. sp.) produce polyunsaturated fatty acids (PUFA) 18:3w6 and 20:4w6. These species (along with a non PUFA producer, .i.Rhizobium./i. sp.) were isolated from the gut content or body surface of .i.Mesoniscus graniger./i. (Frivaldsky, 1865) (Crustacea: Isopoda). Bacterial strains were tested for activity of nine saccharolytic enzymes. .i.Chryseobacterium./i. sp. showed amylase, maltase and cellobiase activity, other bacterial species only had amylase activity. As PUFA and enzymes may be essential for animal growth and development, colonies of the four strains were grown for further use in laboratory food selection and reproduction experiments with .i.E. crypticus./i..
|
|
|
Some biological characteristics of the invasion species Perccottus glenii
Halačka, Karel ; Vetešník, Lukáš ; Koščo, J.
The occurrence of this exotic species was first observed in the Latorica River, E Slovakia, in 1998. Perccottus glenii occupied the rivers Latorica, Bodrog and Tisza together with the aquatic habitats in their floodplains. We carried out analysis of growth, haematology, fecundity, morphology of skin and gonad of individuals Amur sleeper in the locality at Svata Maria (the Bodrog River drainage area). In the locality under study the invasion of Perccottus glenii resulted in an almost total destruction of numerous populations of the native species Umbra krameri, Carassius carassius, and Leucaspius delineatus. In the past, these species were among the most numerous in that locality. Perccottus glenii has appeared to be a typical 'invasive' species that is a serious threat for native fish species showing identical habitat requirements.
|
|
|
Growth of the sterlet (Acipenser ruthenus) under conditions of Pohořelice Pond Fisheries
Baránek, V. ; Prokeš, Miroslav ; Baruš, Vlastimil ; Peňáz, Milan ; Mareš, J. ; Spurný, P. ; Němec, R.
Growth results of the sterlet (Acipenser ruthenus) reared at the Pohořelice Pond Fisheries were observed in 2003 and 2004 and subsequently analysed. During the period 28 July ů 2 September 2003 a feeding experiment (sterlet of age 1+ and 4+, 5+) was performed in which very good growth parameters were achieved: In the age category 1+ (initial mean weight of 99,5; 71,2 and 53,8 g) using DFR 1,6; 1,7; 2,1 % respectively, SWGR 1,02; 1,36; 0,91 %.d-1 , respectively and FCR 1,45; 1,10 and 2,38, respectively. In the age category 4+, 5+ (initial mean weight of 316,9; 375,0 and 478,85 g) using DFR 1,3; 1,1 and 0,9 %, respectively, SWGR 0,88; 0,73 and 0,59 %.d-1 , respectively and FCR 1,35; 1,39 and 1,42, respectively. On the basis of these results, sterlet may be considered to be an appropriate fish for intensive aquaculture and, as a native species for the Czech Republic, also for stocking into Czech running waters.
|
|
|
Foraging strategy of ungulates on Pavlovske vrchy hills
Heroldová, Marta
Study on foraging strategy of three ungulate species (Capreolus capreolus, Capra aegagrus, Ovis musimon) elucidates the problem of mutual coexistence and competition. High impact on unique flora of Palava Hills leaded to decision to lower the number of ungulates and eliminate Capra aegagrus from this locality.
|
guest ::
