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Analysis of selected localities suitability for freshwater pearl mussel young stages in upper stretch of Vltava River
Myslivečková, Lenka ; Bílý, Michal (advisor) ; Alena, Alena (referee)
In the river basins of Teplá Vltava and Blanice in Šumava, samples of floating and deposited detritus were taken for the purpose of their physical and chemical analysis with the goal to identify suitable stations for the growth and development of juvenile specimen of freshwater pearl mussels. 6 locations in total were examined (5 in the river basin of Teplá Vltava, 1 in the river basin of Blanice) where bio-indicator tests were also conducted. In all these locations, samples were taken 3 times during the month of July and, in 1 location, once a month in the period from June to November. In the samples, the amount of Ca, P, K, Mg, Na, the proportion of organic component and the ratio C/N were determined. This analysis showed that short-term oscillations of the composition of detritus correlate, regarding their span, with seasonal changes. The dependence of such seasonal changes of detritus on the extent of the river flow rate was not proved. Differences in the amount of organic component, K, Mg, and the ratio C/N between floating and deposited detritus were found. In terms of qualitative composition, both types of detritus varied in the amounts of plant and inorganic particles. In comparison with available results from springs in the area of Blanice, the detritus from rivers differed significantly from the detritus originating in springs in the presence of faecal pellets, amorphous matter and plant particles.
The growth of freshwater pearl mussels was dependent on the water temperature in the river, a dependence on the tested parameters of detritus was not proved, varying trends, however, were discovered (e.g. higher content of P, better growth). Water temperature showed to be dependent on the horizontal profile: water temperature rises with the direction of the water flow and the content of organic component in the detritus decreases with the direction of the water flow. Other trends in the horizontal profile were discovered as well but they were not proved statistically. Based on biological indicators, the locality of Ovesná (the lowest point down the river Teplá Vltava) was assessed to be the most suitable station.
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