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Utilization of organism Daphnia magna in ecotoxicity tests
Winklerová, Lucie ; Vávrová, Milada (referee) ; Zlámalová Gargošová, Helena (advisor)
This thesis deals with ecotoxicity tests of selected substances used in agriculture and horticulture. It is focused on the determination of acute and chronic toxicity of selected herbicides. These herbicides are sold commercially, specifically Finalsan (active substance is nonanoic acid), the product of Neudorff GmbH KG company, and Dominator (active substance is glyphosate, isopropylamine salt) by Dow AgroSciences Ltd. Next tested substances are potassium nitrate and sodium nitrate - common agricultural fertilizers. Potassium dichromate was also tested. Potassium dichromate is very toxic for aquatic environment and it is used as the standard in acute tests. Tests were carried out in terms of effects on aquatic systems, due to very good solubility in water of selected substances. The tests were performed on the organism Daphnia magna.
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Study of the limnological components of the ecosytem of Lake Medard in 2022
Peterka, Jiří ; Hejzlar, Josef ; Nedoma, Jiří ; Znachor, Petr ; Seďa, Jaromír ; Vejřík, Lukáš
The report summarizes the results of research into the limnological and biological components of the ecosystem of the newly created Medard post-mining lake. The aim of the presented report is to summarize the results achieved for the year 2022 and recommendations for further monitoring. The year 2022 was the fifth year after the lake was completely filled, when water from the Ohře River was no longer added. Only small tributaries flowed into the lake from its own catchment area, and at the same time, water from the lake drained through seeps, which are apparently drained into the nearby rivers, the Ohře and the Svatava. The lake ecosystem reached the final state of its initial phase in terms of hydrological regime and nutrient load. This condition is characterized by very little water exchange and a low nutrient level with low productivity of plankton communities. There is the development of submerged macrovegetation in littoral zone and a specific seasonal change in chemistry and biological parameters. However, the aquatic ecosystem is still far from stabilized and the biological communities of the littoral zone (littoral) and open water (pelagial), including the fish community, still show significant interannual dynamics.
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Potrava násady kapra (Cyprinus carpio L.) v rybnících - analýza obsahu zažívadel.
SÝKORA, Ondřej
The aim of this bachelor thesis was to comprehensively evaluate the diet of two-year old common carp in semi-intensive pond culture from the stage of two-year carp (K2) to the stage of market carp (Kt). The extent to which the carp use natural and presented food and whether its composition changes during the season was monitored. The experiment itself was part of a large-scale GAČR project (Nutrients from Fish or Nutrition for Fish: Revealing Hidden Risk of Pollution and Nutrient Retention in Ponds through Nutritional Bioenergetics of Fish), which was conducted at the experimental facility of the VÚRH Vodňany. The experiment of food study was conducted in three ponds (0.16 ha), which were slowly filled from mid-April onwards, for the development of natural food after being left dry. Subsequently, 150 individuals of carp (337 ? 57 g) and 35 individuals of pikeperch (S. lucioperca L.; W=14.5 ? 38.8 g), were stocked on 26th April 2022 to prevent the development of undesirable fish species. Carp rearing lasted 162 days, during which time carp diet was monitored approximately once a month using the flushing method of Faina (1975). The contents of intestines of four carps were collected from each pond, at each date. At the beginning of the season, the diversity of the diet was high. Zooplankton was the most abundant food component throughout the entire experiment. However, if we consider the size of the feeding organisms, zoobenthos, consisting mainly of chironomid larvae, played a significant role in the diet of the carp at the beginning of the season. As the season progressed, the number of zoobenthos individuals decreased, while the number of zooplanktonic organisms in the diet increased, mostly represented by planktonic cladocerans and copepods. These two groups of organisms also had the highest frequency of occurrence and abundance in the digestive tract throughout the experiment. Along the season, in addition to the increasing abundance of zooplanktonic organisms, the proportion of grains in the carp diet also increased.
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Rozvoj zooplanktonu v rybnících s produkcí rychlených stádií hospodářsky významných druhů ryb
PECHA, Oldřich
This master thesis was focused on zooplankton development in ponds with advanced fry rearing of economically important fish species. For the purpose of my study, we sampled pond cascade that is managed by Štičí líheň - ESOX, spol. s r.o. in the village Liderovice, near Tábor. In this particular pond cascade, the annual production of advanced fry of economically important fish species takes place, namely pike, pikeperch, carp, tench and grass carp. Importantly, pond cascade is used several times during one growing season, and zooplankton is the main food source of all early stages of rared fish. For the production of advanced fry of fish served 3 ponds, which were released and refilled 2-3 times a season. Fourth pond served as a control stocked with one year old carp throughout the whole season. The water from an upper pond in the cascade served as zooplankton inoculum to a lower pond after the pond harvesting. Statistical analyses showed that the fry of different fish species in ponds lying in the same cascade does not affect the composition of zooplankton after restocking and water refilling. The only difference we noticed was in the treatment with pikeperch, which partially does not share the food base of other monitored species.We also found out, that the occurrence of Cyclops vicinus, Daphnia magna, D. ambigua or D. pulicaria was positively correlated with increased P-PO4 concentrations. We also confirmed that pond ecosystem can effectively retain nutrients from basins and use them for its production. As was shown after a short rain when the measured concentration of total phosphorus in the inflow in our pond system was 0.50 mg/L, on the contrary in the last pond of our cascade we measured values below 0.08 mg/L. High transparency was maintained in the whole cascade throughout the monitoring period, and an adequate economic profit was generated. Such management can be applied to only a few ponds (systems).
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Potravní zdroje plůdku reofilních ryb v rybnících s instalovanými světelnými a barevnými atraktanty hmyzu
KAJGROVÁ, Lenka
The aim of this work was to evaluate the food base (zooplankton, zoobenthos and aerial insects) and production results in culture of two-year-old golden ide (Leuciscus idus aber. orfus) and chub (Squalius cephalus). The specifics of the study were to use the attractants (yellow plates) and submersed lights as a supplement to the nutrition of farmed fish. Experimental rearing took place in the earth ponds in the area of Experimental Fish Culture Facility in Vodňany (Czechia) and in the storage ponds in Schlossfischerei Schönau bei Litschau (Austria). Zooplankton composition and physico-chemical parameters were monitored during regular two-week sampling periods. Monitoring of zoobenthos and terrestrial insects captured by attractants was performed at monthly intervals. Macrozoobenthos was sampled by Ekman Grab. After processing the samples in the laboratory, the benthic invertebrates were divided into three groups - Chironomidae, Oligochaeta and Varia. Zooplankton was collected by planktonic mesh in the 3 m long hauling and divided into the fraction of small zooplankton (Daphnidae < 499 micrometre, Copepoda < 999 and > 1000 micrometre and Others - small Cladocera), and into the fraction of coarse zooplankton (Daphnidae 500 - 999, Daphnidae 1000 - 1499 and > 1500 micrometre). Terrestrial insects were captured by installed attractants for a specified time period of day (colour attractants) or night (light attractants). The results show that the environmental conditions of the monitored ponds did not differ significantly. Abundance of coarse zooplankton in both experimental cultures was influenced by fish. The density of zoobenthos did not differ significantly. However, the values in the ponds with the lights were higher than in the control. According to the analysis of growth and production data, the installation of insect attractants as a supplementary measure to fish nutrition in aquaculture seems to be beneficial for production results. The average weight of golden ide increased during the growing season from the initial 4,3 g to 26,9 +- 4,9; 32,3 +- 6,5 and 41,2 +- 9,2 g in control ponds, ponds using lights and yellow plates, respectively. The differences between both control and experimental treatments as well as between lights and yellow plates were highly significant (p < 0,001). In the culture of chub using light attractants, the average fish weight increased from the initial 12,7 g to 41,9 +- 2,2 g, respectively to 26,7 +- 5,5 g in control. In both treatments, the production was analogously higher.
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Zooplankton vysoce eutrofních rybníků - srovnávací studie různých metod vzorkování
IŠTOK, Tomáš
Evaluate different methods of zooplankton sampling during different stages of zooplankton development in highly eutrophic ponds. Record the abundance, biomass and relative composition of key taxa during the season in selected localities, in order to capture very different situations. Evaluate the samples taken by various methods and assess the options appropriate for fishing practice.
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Je zooplankton schopen živit se pikoplanktonními sinicemi?
ŠVECOVÁ, Miroslava
The aim of the bachelor thesis is to look into the composition of waters and focus on the investigation of picocyanobacteria. Theoretical part mainly covers ecology, morphology, species diversity and distribution of these organisms. A significant part of the bachelor thesis also deals with the consumption of picocyanobacteria by zooplankton in various areas. The practical part contains research of growth curve of picocyanobacteria performed on six different cultures grown in two cultivation media for 84 days. During this period, individual samples were taken regularly. The research displays interesting results about growth of picocyanobacteria in dependence on observed time, cultivated medium and type of culture.
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