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Food composition and feeding selectivity of zooplankton
Lis, Jonáš ; Škaloud, Pavel (advisor) ; Čablová, Radka (referee)
Zooplankton are an important link in the food web between phytoplankton and higher tro- phic levels, and understanding their feeding preferences is the key to unraveling the functions and dynamics of aquatic ecosystems. Current knowledge of zooplankton food composition is limited, consisting mainly of laboratory experiments that have revealed different hunting strategies and selection of prey based on size and nutritional value. Recently, publications have emerged that, through the use of DNA metabarcoding, provide a completely new and comprehensive insight into the diversity of zooplankton diet composition, especially copepods, cladocerans and rotifers. These methods reveal that the feeding niches of copepods and cladocerans are distinct and do not overlap. In general, both groups are said to prefer mainly diatoms as their food, when available. The food niches of rotifers are so diverse that no clear trend can be established for the entire phylum. Cyanobacteria appear to be the main source of energy for zooplankton and are proba- bly consumed by metazooplankton largely as secondary prey when consuming ciliates and other heterotrophic prey. Furthermore, differences in feeding niches between species are known and can be partly explained by their vertical distribution, and different levels of feeding...
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Biogeography of the herpetofauna of the Aegean Islands
Sýkorová, Marta ; Šmíd, Jiří (advisor) ; Papežík, Petr (referee)
In the last thirty years, the biogeography of the herpetofauna of the Aegean Sea has been the subject of thorough research. In evolutionary biology, islands are considered to be model ecosystems. Morphological, physiological and behavioral changes in some species can be observed on them. These changes are described as so-called "island syndromes". The occurrence of these syndromes depends on the size of the island, its distance from the mainland and the age of the island as well as on population density, availability of resources and presence of predators. The specific manifestations of these syndromes in reptiles of the Aegean islands are: the occurrence of endemism, gigantism and dwarfism, color changes, more frequent tail autotomy, cannibalism and food specialization. Most of these changes are described in lizards of the Podarcis genus, especially on Podarcis erhardii, as it is the most widespread reptile in this area. The second very widespread and therefore often researched reptile is Mediodactylus kotschyi. Changes often take place on small islands, so individuals tend to be compared with members of the same species from a larger island or mainland. The number of endemic species is significantly higher on islands that are longer separated from the mainland. The existence of gigantism and...
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Interspecies differences in the cognitive abilities of corvids
Myslivečková, Lucie ; Fuchs, Roman (advisor) ; Sedláček, František (referee)
Birds from the family Corvidae are considered to be intelligent birds. Many species from this family are subjects of experiments that study their cognitive abilities. This thesis was focused on gathering and evaluating of comparative studies about interspecies differences in the cognitive abilities of two or more species. A part of the thesis was also dedicated to interspecies differences in cognitive abilities in corvids and other animal species. Result is that there are interspecies differences in cognitive abilities of corvids. These differences are cause mostly by their feeding ekology and the sociality of the specie. The success rate of different species can change depending on the experiment. Key words: Corvidae, corvids, cognitive abilities, interspecific comparison, comparative approach
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Influence of ants on soil chemistry across biomes
Kostečka, Luboš ; Frouz, Jan (advisor) ; Jílková, Veronika (referee)
Ants are important ecosystem engineers. Their activity has direct and indirect influence on soil chemistry inside their nest through processes such as bioturbation or accumulation of organic matter and its decomposition by the microbial community. These processes depend on environmental conditions such as soil properties and climate. However, there has not yet been a comparison of this influence on soil chemistry across different biomes. The aim of this thesis is therefore (1) describe the processes through which ants influence soil chemistry (2) summarize the resulting influence on soil properties such as the concentration of nutrients and the pH level in the ant nests and the surrounding soil (3) find out whether there is a common trend to these influences across biomes, or if every biome has its own specific trend. The findings of this thesis point to the conclusion that while there is a common trend across biomes, it heavily depends on conditions such as nest structure, feeding strategy of a particular species and the climatic conditions of the given ecosystem. Key words: ants, soil, soil chemistry, biomes, nests, bioturbation, feeding strategy, macronutrients, pH, environmental conditions, climate
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Food webs of glacier-fed streams.
Komárková, Julie ; Kopalová, Kateřina (advisor) ; Fuksa, Josef (referee)
This work focuses on glacier-fed stream ecosystems, with the centre of attention being on the community composition and characterization of their food web structure. Glacier-fed streams are harsh environments in terms of their physicochemical characteristics. These streams exhibit low temperatures and specific flow regimes, with the peak of meltwater generation, and thus discharge, in the summer. In turn, streamwater nutrient concentrations, light availability, and turbidity all vary seasonally according to the flow regime. Compositionally, glacier-fed stream habitats host chemolithotrophic bacteria along with photoautotrophic producers, such as diatoms, Chrysophyceae, and Cyanobacteria, which together serve at the bottom of food webs as primary producers. These streams also host some fungal taxa, that together with heterotrophic bacteria, represent the primary decomposers. Macroinvertebrates, including the water larvae of species Diamesa and Pseudodiamesa, or from the Ephemeroptera or Plecoptera groups, are important secondary producers with high feeding plasticity; that is, they are mainly grazing biofilm or collecting/filtering organic matter, with the possibility of predation. Other than that, in glacier-fed streams, there is usually no presence of higher trophic levels with large- bodied...
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Fate of micropollutants during vermicomposting
Nehasilová, Alena
Vermicomposting is recently becoming a rather popular environmentally friendly technique for stabilizing biowaste, including sewage sludge. There is an effort to utilize the sewage sludge as fertilizer on agricultural land. But apart from nutrients, the sludge also contains harmful pollutants, which subsequently after its deposition on fields can be taken up by plants and organisms contaminating the food chains. Micropollutants, the substances that can be found throughout the environment in trace concentrations, are one of the pollutants occurring in sludge. It is for example pharmaceuticals and personal care products, per- and polyfluoroalkyl substances, or pesticides. Their negative effects are known - they can be for instance endocrine disruption, antibiotic resistance, or the development of cancer. Although the deposition of sewage sludge on fields as a fertilizer is one of the main introduction routes of micropollutants to the environment, the content of micropollutants before deposition is not monitored nor regulated. This dissertation focuses on the fate of micropollutants during vermicomposting, especially in sewage sludge substrates. The vermicomposting method was applied to stabilize coffee spent grounds and sewage sludge obtained from distinct wastewater treatment plants mixed with...
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Vliv hlaváče černoústého (Neogobius melanostomus) na potravní řetězec řeky Ploučnice
STANĚK, Pavel
Biological invasions are prominent factor affecting changes in invaded ecosystems. Invasive species can alter in food web of the indigenous community, which leads to changes in the community through ecological and economic effects. This work was focused on the effect of the Round goby (Neogobius melanostomus, Pallas 1814) food web of river Ploučnice. Round goby was first recorded recently in the Czech Republic (2015). Thus, it can still be considered a young invader into Czech inland waters. The main goals of this thesis were: I) to reveal Round goby food source preferences, II) to Competition between Round goby and European bullhead (Cottus gobio, L 1758), as this species is a native endangered species present at this locality. III) Possible preferences of Round goby as a putative food source of predatory fishes in sampled localities. For this purpose, River Ploučnice has been chosen. River Ploučnice flows into Elbe River, which is fully invaded by Round goby. Thus, the bottom part of the Ploučnice River is invaded by Round goby as well. However, thanks to the presence of migratory barriers between localities, Round goby has not yet been detected in localities upstream. To reveal mention goals all biota units in all localities were sampled. Later, stable isotope analysis (carbon and nitrogen) followed by Bayesian models were employed. In general, results suggest that this species had the highest abundance among other species in localities with an established Round goby population. In addition, results reveal Round goby as a true generalist regarding food source preferences. Comparing trophic niche width and overlap showed a significant overlap between some of the ontogenetic groups of round goby and European bullhead, reaching up to 67,8 %. Also, increased niche overlap between ontogenetic stages of European bullhead was observed when Round goby was present, in comparison to localities without the presence of Round goby. Additionally, predatory fish food preferences showed no specialization on round goby as a food source, although round goby was part of their diets. In conclusion, this was found round gobyas a consumer, competitor, and even as a food source for predatory fishes.
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Od trusu k prostřenému ubrusu. Molekulární analýza potravy raka signálního
ŠKRABÁNEK, Jan
This thesis aimed to determine the diet of the signal crayfish in Křesánovský brook in 2020. In addition to that, we aimed to find and test suitable markers for the diet analysis of signal crayfish, which are described in the thesis. We analyzed the crayfish diet by examining DNA from faecal pellet samples collected monthly from April to September. By using group-specific DNA markers, we targeted the main dietary groups such as Heptagenidae (markers Hpt28Sf + Hpt28Sr), Ephemeroptera (Epa28Sf + Epa28Sr), Integripalpia and Spicipalpia (Inspi18Sf + Inspi18Sr), Plecoptera (Ple-gen A269 + Ple-gen S268), Chironomidae (Chiro18Sf + Chiro18Sr), and Gammaridae (Gamae28Sf + Gamae28Sr). We also focused on representatives of macrophytes Characeae (CHA677 + CHA1681R) and Eudicotyledons (MYR152F + MYR1696R). The results showed that the crayfish's diet varied during the sampling season. Gammaridae was the most common food item, found in 54.1% of the samples of faecal pellets. Heptagenidae, Integripalpia, and Spicipalpia were also significant, present in 31.3% of the samples. Plecoptera appeared in 20.8% of the samples, while Chironomidae and Characeae were found in 10.4%. Eudicotyledons were detected in 8.3% of the samples. Ephemeroptera were the least common food group, detected only in 2.1 %. Gammaridae were the most significant component of the crayfish diet in April (found in 7 samples), while Heptagenidae were the second most abundant component. The diet was more diverse in May, but Gammaridae remained the primary food source, followed by Integripalpia and Spicipalpia (in 5 samples). In June, Gammaridae was present in all samples, while Heptagenidae and Integripalpia/Spicipalpia were significant. In July, Heptagenidae was the most common food group (found in 5 samples), with Gammaridae found in 4 samples. No food items were detected in the samples from August and October, and only one sample contained Gammaridae in September. Overall, this study provides insights into both the seasonal variations in the diet of signal crayfish and markers suitable for its analysis.
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Aktivita raka mramorovaného v závislosti na reprodukčním cyklu
MARKOVÁ, Kateřina
The aim of this thesis was to elaborate a literature review on the topic of crayfish activity, in particular their feeding activity and the use of shelters, including an emphasis on the role of sex and the reproductive cycle. I also focused on the characteristics of the marbled crayfish, Procambarus virginalis Lyko, 2017 and its usability as a model organism. The experimental part of the thesis focused on comparing three groups of female marbled crayfish (with ovulum, with glair glands and without ovulum). Experiments have been carried out using a method for ecological assessment of feeding behavior and predator-prey relationship in various prey densities in the form of larvae of buzzer midge Chironomus plumosus (Linnaeus, 1758) by functional response analysis and subsequently tested for the effect of shelter presence at uniform prey densities levels. In our experiment, all three groups of tested females showed a type II functional response typical of predators. The results indicate that females without ovulum have been the most active in terms of food collection in all cases, with a generally positive effect of the presence of shelter. Females with employed ovulum are generally less active in terms of consumption, processing and overall aktivity due to hormonal, physiological and consequently behavioural changes. Females with glair glands behaved similarly to females with ovulum in our experiments, being more cautious and less active than females without ovulum. This was probably due to their increased gonadosomatic index (GSI) and, conversely, their decreased hepatopankreas to total body weight ratio, which renders these females unable to physiologically ingest large amounts of submitted food. Female GSI decreases again after ovulation, nevertheless, even females with already employed ovulum did not consume more food, as females prefer safety at this stage of the reproductive cycle. They are less active, move more slowly, spend more time in a shelter, tend to their eggs, and thus cannot devote themselves fully to hunting and prey processing. Regarding its life strategy, the marbled crayfish is a generally suitable model organism for use in various areas of research, however, it is important to take into account its rapid life and reproductive cycle and adapt the conditions of the given experiments to this fact, as the parallel use of female marbled crayfish at various stages of the reproductive cycle can modulate results in terms of their activity. Certain differences in the presented results may also be due to the origin of the experimental animals, as with very few exceptions all performed experiments with marbled crayfish have been carried out using laboratory individuals. A number of conditions that change seasonally in nature have been kept constant in the laboratory. Therefore, it is important to keep in mind that in wild, crayfish are also exposed to both biotic (predation pressure of various species of fish, birds or mammals) and abiotic (changes in temperature and water chemistry) factors that can influence food activity. Nevertheless, we assume that the patterns observed here will also be valid for female crayfish living in the wild nature. However, the lack of similar experiments leading to the elucidation of female activity depending on the stage of the reproductive cycle provides a room to investigate other, not just crayfish species.
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Náhrady škod způsobené zvláště chráněnými druhy zvířat
SMÍTKOVÁ, Michaela
A large number of specially protected species of animals live in our region. The protection of these species is in the public interest. Farm animals are also an integral part of the food composition of some of the specially protected species. This ba-chelor's thesis deals with the issue of compensation for damages caused by specially protected species of animals, such as the lynx and the common wolf, to farm anima-ls. From all the sources of information that became the basis for this work, it is clear that there is a gradual decrease in the damage caused by specially protected species of animals to farm animals in the area of interest (Pilsen region), which may be caused by the gradual adaptation of farm owners to the presence of these beasts and by ap-plying some of the preventative measures in their farms.
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