|
| |
|
|
Drinking water reservoir Nýrsko - influence of macrophytes on water quality
Hejzlar, Josef ; Hohausová, Eva ; Komárková, Jaroslava ; Kopáček, Jiří ; Peterka, Jiří ; Duras, J.
The importance of macrophytes in P cycling was studied in Nýrsko Reservoir, an oligotrophic water body in western Bohemia. A comparison of the external P loading with the P content in macrophytes of Nýrsko Reservoir in 2004 demonstrated that macrophytes can play a significant role in P-cycling also in deep, pelagial-dominated water bodies on condition that the external P loading is low and macrophytes have appropriate conditions for their growth (mainly small extent of water level fluctuation). Nýrsko Reservoir is an apparent example of situations from limnological textbooks when macrophytes function as a stabilizer of the aquatic ecosystem with an efficient zooplankton grazing on phytoplankton allowing suitable water quality for drinking water production.
|
|
|
The fluorescence assay of aminopeptidase activity as an alterantive indicator of water quality?
Vrba, Jaroslav ; Svoboda, J. ; Fuksa, J. K.
Recent water quality/pollution control uses standard chemical, biological or microbiological indicators that provide information on water status with a delay of several days. Though they characterise direct impact of released compounds on water quality in a recipient, they do not well reflect consequent reaction of the ecosystem on increased pollution. Following the Water Framework Directive 2000/60/EC we focused on such alternative microbial indicators that would allow for instant evaluation of ecological status of running waters and ongoing in-stream processes. Recently, activities of different extracellular enzymes have been suggested as indicators of both trophic status of lakes and organic or faecal pollution of streams. This contribution evaluates an indication potential of the extracellular aminopeptidase assay.
|
|
|
New records of Chironomus MEIGEN species (Diptera, Chironomidae) in the Novohradské Mountains (South Bohemia)
Matěna, Josef ; Matěnová, V.
C. longistylus Goetghebuer and C. sp. South Bohemia were found as new species for the Czech Republic. Karyotype of the new species is presented together with preliminary mapping of chromosomal arms A, C, D, E, F. C. cingulatus, melanescens, nuditarsis, uliginosus and C. (Camptochironomus) palidivittatus are recorded for the first time from Novohradské Mountains. Notes about distribution and ecology of these species are given.
|
|
|
The occurrence of brook lamprey [Lampetra planeri (BLOCH, 1784)] in Novohradské Mountains (South Bohemia, Czech Republic)
Matěnová, V. ; Matěna, Josef
The occurrence of brook lamprey was studied in Novohradské Mountains during 1999-2003. Altogether 83 profiles on 22 second to fourth order brooks and streams were fished by means of electroshockers. The area investigated can be divided into three basins. Significant differences were found between basins with respect to frequency of occurrence and density of lamprey populations. The highest frequency of occurrence was in the Stropnice River basin (6 streams of 8 investigated, average abundance 2598 inds ha-1), followed by the Malše River (4 streams of 8 investigated, average abundance 844 inds ha-1). In the Černá Rivulet basin only in 1 of 6 streams investigated the brook lamprey was found at very low densities - 28 inds ha-1 on average. The lamprey contributed substantially to the whole forming more than 50
|
|
|
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.
|
|
| |
|
|
Phosphorus release from sediments - a comparison of methods
Borovec, Jakub ; Brzáková, Martina
Phosphorus release rates from sediments were compared at two localities of Jordan Reservoir (Czech Republic) during the year. The release rates measured by incubation method were an order of magnitude higher comparing to the release rates calculated from phosphorus gradient in pore-water. A rapid decomposition of freshly settled seston at the sediment surface or just above the sediment was suggested to explain the differences.
|
|
| |
|
|
The genus .i.Chironomus./i. MEIGEN (Diptera, Chironomidae) in the Novohradské Mountains (South Bohemia)
Matěna, Josef ; Matěnová, V.
The occurrence of Chironomus species was investigated in Novohradské Mountains during 1999-2001. Fishponds, running waters and small standing waters of both permanent and astatic characters were included. Larvae were identified cytotaxonomically according to polytene chromosomes of salivary glands. Ch. annularius occurred more regularly in fishponds without fishery management, further species were found only in some of these habitats - Ch. balatonicus, bernensis, obtusidens, parathummi, plumosus, sp. - near muratensis and Ch. (C.) tentans. Organically polluted stretches of running waters were characterized by mass occurrence of Ch. riparius. Ch. luridus and Ch. melanotus were the dominant species of small permanent water bodies, further species found in these habitats were Ch. aberratus, commutatus, dorsalis, holomelas, piger and pseudothummi. Astatic habitats - rainpools were inhabited almost exclusively by Ch. dorsalis.
|
guest ::
RSS feed.