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Je vysazování rychleného plůdku lipana podhorního vhodným postupem pro podporu tohoto druhu ve volných vodách?
PASTEJŘÍK, Jan
This thesis focuses on the possibilities of supporting or restoring populations of the brown trout in Czech streams. Due to the effects of many negative factors, the populations of brown trout in our streams have significantly decreased, and the artificial introduction of reared individuals has so far proven to be ineffective. The aim of the thesis was to assess the possibility of strengthening or restoring the population of brown trout in selected sections of streams by introducing quick-growing fry reared in pond conditions. A significant number of recaptured individuals in all monitored locations indicates that the fish are capable of surviving and prospering in a new environment. During recaptures, it was found that the introduced fish formed a significant proportion of the fish communities present in the experimental sections. Successful overwintering of some of the introduced individuals was demonstrated in all locations. The use of alizarin solution as a bath for marking brown trout fry is an appropriate method for the efficient marking of a large number of small individuals with the possibility of detecting marks in the field without the need to kill identified individuals. The production and introduction of quick-growing fry of brown trout appear to be a promising approach for restoring and supporting their populations in free waters.
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Perfluorované látky ve vodním životním prostředí
TLAČILOVÁ, Hana
Perfluorinated and polyfluorinated substances (PFAS) are synthetic compounds with a wide range of applications due to their specific properties. PFAS are highly stable substances not subject to biochemical, chemical, thermal, or photochemical degradation. They are in most cases persistent and bioaccumulative. This work deals with detecting the occurrence of 33 PFAS representatives in benthos, juvenile fish, muscle samples of adult fish, and water using POCIS passive samplers. The 27 sites selected for sampling were profiles operated by the CHMI for surface water monitoring, located on some of the major rivers of the Czech Republic The obtained samples were analyzed using high-resolution mass spectrometry with high-performance liquid chromatography (HPLC-HESI-HRPS). The concentrations of the monitored substances were evaluated using TraceFinder 3.3 software (Thermo Fisher Scientific, USA). The analysis detected 13 PFASs out of the 33 monitored substances, namely PFOS, FOSA, PFDoA, FHpPA, H4PFUnA, PFBS, PFHxS, PFTeDA, PFTrDA, PFHpS, 6:2FTS and PFHpA. At the Ohře - Želina site, the highest concentrations were measured in juvenile fish samples, with total PFAS concentrations reaching up to 887.7 ng×g-1, specifically 620 ng×g-1 PFHxS, 260 ng×g-1 PFOS and 7.7 ng×g-1 PFTrDA, and in benthic samples, with total PFAS concentrations of 147 ng×g-1, specifically 120 ng×g-1 PFHxS and 27 ng×g-1 PFOS. The highest concentration in the muscle samples was measured at the Elbe - Obříství site, 200 ng×g-1 sum PFAS. In the POCIS samples, the highest sum PFAS was estimated at the Elbe - Litoměřice site, with a concentration of 29 ng×g-1. The results of the analyses demonstrated the necessity of combining multiple sample types to obtain the vast range of captured compounds.
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Variability of mercury concentrations in adult and juvenile fish
HOLAŇ, Viktor
The thesis compares variability of mercury concentration among adult and juvenile fish in order to streamline monitoring of water environment contamination. In terms ov thw thesis there were monitored two localities: Labe Děčín and Labe Kozly. Adult fish were caught usingdeep-water electrofishing equipment and juvenile fish were caught using back-pack electrofishing equipment. Two variations of mercury concentration were compared, one in muscle of particular adult fish species, second in whole bodies of juvenile fish. Mercury concentrations were also compared among particular juvenile fish fish species in particular localities. All analyses were performed using spectrophotometer AMA 254. It was proved that analyses of juvenile fish are suitable and more cheaper than analyses of adult fish, when it comes to monitoring.
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