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The American mink is among the weaselly (Mustelidae) carnivore native to North America. It is a food opportunist living semiaquatic lifestyle. He is very well adapted to the new environment. And he was introduced by humans as a furry animal to many areas of Europe, Asia, South America and other areas. Secondarily often he escaped or were released into the wild, where he managed very well prosper and continue to reproduce. To the Czech Republic came as a furry animal in 20. to 30. years of the last century, in the wild he was then observed since the 60s. This study examines the impact of American mink on our fauna, especially in view of the food spectrum. The research was conducted in the middle of the river Berounka in Křivoklát from December 2014 to December 2015. The aim of the study was to capture the largest possible number of minks during the summer and in winter. Another aim was whether mink dangerous for the local population of reptiles. Trapping took place during the 552 trapping night. a total of 20 were trapped mink. This means that the average captured 1 mink to 28 trapping night. Of these 20 individuals were 5 females and 15 males. It caught up to 8 mink in the winter and 12 in the summer. Based on the analyzes were 7 mink (35 %) excluded from the analysis because of an empty stomach. The largest component of food mink accounted for 76.16 % mammals for example order: Rodentia eg. vole (Microtus arvalis), muskrat (Ondatra zibethicus). Other food components formed on the same level with a share of 7.69 % reptile grass snake (Natrix Natrix), birds (order: Passeriformes) and fish (class: Actinopterygii). The last component of food occurring in the samples was 0.77 % of the insects (orders: Coleoptera, Lepidoptera). In the analysis wasn´t detected representative of the class of amphibians (Amphibia). The food spectrum in the winter and summer season was no different. At-risk populations reptile shows finding snakes in the stomach mink. An important outcome of this study is also alert to legislative issues concerning the mink in the Czech Republic and the possible effects on the otter (Lutra Lutra).

Bromus sterilis L. (barren brome) spreads rapidly in many European regions. In the Czech Republic, its importance has increased dramatically over the past 10 years. Barren brome is reported as a problem weed in winter crops such as winter wheat, winter barley and oil seed rape, in vineyards and in other cultivated places. Barren brome has been becoming troublesome weed of winter cereals mainly in reduced soil tillage systems. The factors, that are important for its spreading and adaptability under different environmental conditions, are dormancy and germination. Optimal timing for seed germination varies with respect to natural conditions and it is determining for plant development. These traits are adapted to different conditions and habitats; therefore the dormancy and germination response patterns to those conditions vary significantly. Recently there are not many information available on germination behaviour, therefore this study was focused on seeds of barren brome and its characteristics, which were collected in different regions of the Czech Republic. Seeds were investigated under different temperatures, light regimes and water stress in a wide range of conditions. The following characteristics of seeds were studied the dormancy, the dynamics of germination, the temperature optimum, the age of seeds and dynamics of emergence from different depths and persistence in the soil profile under field conditions. Dormancy and germination are influenced by external conditions. The dormancy of seeds barren brome is very short or missing. The germination is influenced by light; the seeds germinated better under darkness than under light regime. The primary dormancy of B. sterilis was short and the seeds needed only three weeks for after-ripening. The seeds of B. sterilis showed broad ecological valence to hydrothermal factors germinating in the wide range of 3 to 35 °C. The temperature optimum is 5-23°C. The germination was only slightly influenced in an environment with low water potential. Germination was limited under water stress only at lower temperatures under 10°C. The response to light at various temperatures showed that seeds germinated better in darkness in all temperatures regimes, than in alternating light regime, especially at lower temperatures. The emergence declined significantly with burial depth (under 40 mm). The seeds were not able to survive in the soil seed bank for a longer time and fall seeds lost viability after 1 year burial in soil profile. These results may be of value for development of predictive models and understanding period when weed control may be most feasible.

This thesis deals with the role of species traits in predator-prey interactions and food web structure. I conducted laboratory experiments with predatory aquatic insects and their prey to reveal the traits determining who eats whom in small standing waters. I also focused on the possibility of incorporating the observed dependence of predator-prey interactions on body mass into existing food web models. Further, I developed a simple simulation model to explore the consequences of body mass dependent feeding and dispersal for food web assembly. Last, I show that four common methods for sampling aquatic insects differ in their selectivity, especially on the basis of body mass of sampled insects. In conclusion, I combined laboratory experiments, field work and mathematical models to evaluate the importance of body mass and other species traits, such as foraging behaviour and microhabitat selectivity, in predator-prey interactions and explored selected food web level consequences.

The gray partridge (Perdix perdix) is a bird species living in hiding and nesting on the ground in the open landscape. Even though this species uses several well-known anti-predator adaptations and strategies, its nests are often predated. The range of nest predators and the circumstances of predation have not, however, been satisfactorily described yet. This diploma thesis summarizes the results of experiments carried out on artificial nests and is supplemented by the description of nest behaviour of two incubing hens obtained from video shooting their nests. This work also includes the results of video shoots of predators on artificial nests, the most common of them being the marten. The successful survival of nests in all experiments was influenced mainly by hiding the nest in vegetation. However, the presence of feather odour of adult birds increased the risks of predation even for well-hidden nests. Nests placed in grass biotopes survived the best regardless their covering. What mattered most in other biotopes (along the edges of field roads, forests or groves and field biotopes off any lines) was the covering of nests with vegetation. Partridges nesting close to the edge of a forest or a grove are not very safe from predators. The fact that both nesting partridges and nest predators prefer a...

The impact of vertical distribution of zoobenthos in a pond in response to the biomass stocking of carp ponds was tested in the Rod, Dobrá Vůle, Pohořelec, Haslauerteich and Neuteich ponds. Except for the Rod pond, various carp biomass was represented in all ponds. Sampling was conducted during the growing season (June and July), and outside the growing season (September). Physico-chemical parameters of water were measured for each sample. All samples were sorted by groups, counted and weighed. The results are presented in graphs. Zoobenthos density of the Dobrá Vůle, Haslauerteich and Neuteich ponds showed a rising tendency towards deeper parts of the pond sediment. The density of these ponds reached the maximum values in depths of 10-14 cm. This tendency was observed in the occurrence of midges in these ponds. The highest density of midges was observed in the Haslauerteich pond (1,687 individuals per square metre). The above-mentioned ponds were stocked by the common carp (K2-3). The largest density of the tubifexes in the Dobrá Vůle, Haslauerteich and Neuteich ponds was observed during the September sampling in the shallow parts of the sediment (0-6 cm). The maximum density was 1,031 individuals per square metre. On the Pohořelec pond, the occurrence of zoobenthos during both samplings was recorded only in the depth of 10-12 cm. Other representatives of zoobenthos were present in the Rod, Haslauerteich and Neuteich ponds. Larvae of Sialis and Chaoboridae were observed as well. The density and biomass was greater in the September sampling. We have noticed a greater settlement in various depths. Their maximum density was in the Haslauerteich pond (218 individuals per square metre).

The predation effects of four fish species on the consumption of free-living cercariae of three trematode species (Plagiorchis elegans, Echinoparyphium aconiatum and Trichobilharzia szidati) were experimentally investigated with regard to specific life-history traits of both predator and parasite. The study provides evidence of a considerable consumption of trematode cercariae by fish and confirms that cercariae play an important ecological role in the energy flow in aquatic food webs.

The impact of vertical distribution of zoobenthos in a pond in response to the biomass stocking of carp ponds was tested in the Rod, Dobrá Vůle, Pohořelec, Haslauerteich and Neuteich ponds. Except for the Rod pond, various carp biomass was represented in all ponds. Sampling was conducted during the growing season (June and July), and outside the growing season (September). Physico-chemical parameters of water were measured for each sample. All samples were sorted by groups, counted and weighed. The results are presented in graphs. Zoobenthos density of the Dobrá Vůle, Haslauerteich and Neuteich ponds showed a rising tendency towards deeper parts of the pond sediment. The density of these ponds reached the maximum values in depths of 10-14 cm. This tendency was observed in the occurrence of midges in these ponds. The highest density of midges was observed in the Haslauerteich pond (1,687 individuals per square metre). The above-mentioned ponds were stocked by the common carp (K2-3). The largest density of the tubifexes in the Dobrá Vůle, Haslauerteich and Neuteich ponds was observed during the September sampling in the shallow parts of the sediment (0-6 cm). The maximum density was 1,031 individuals per square metre. On the Pohořelec pond, the occurrence of zoobenthos during both samplings was recorded only in the depth of 10-12 cm. Other representatives of zoobenthos were present in the Rod, Haslauerteich and Neuteich ponds. Larvae of Sialis and Chaoboridae were observed as well. The density and biomass was greater in the September sampling. We have noticed a greater settlement in various depths. Their maximum density was in the Haslauerteich pond (218 individuals per square metre).

The impact of fish predation on zooplankton assemblage was studied in the mesocosm experiment. Presented thesis focuses on the effect of size selective fish predation on species diversity, biomass and body sizes of zooplankton and the impact of fish occurrence on zooplankton behaviour with regard to diel horizontal migration. I also studied a change in some life history traits of zooplankton caused by fish with a special focus on keystone species of freshwater ecosystems Daphnia spp.

In this master thesis i was tested the effectiveness of the myrmecomorphy.The animals which ones were tested are Phrurolithus festivus the myrmecomorphic spider and the predator, great tit(Parus major). I want to know the adventages and disadventages of myrmecomorph mimicry compared whit other common invertebrates in natural habitat of great tits.