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The trophic ecology of Sargasso Sea fishes
Horák, Mikuláš ; Horká, Petra (advisor) ; Frouzová, Jaroslava (referee)
This work aims to create a comprehensive overview of current knowledge about trophic relationships within and among fish communities in the ecosystems of the Sargasso Sea and tries to deepen our understanding of the intricate trophic dynamics in these waters and contribute to the broader field of marine ecology. The Sargasso Sea is a unique marine environment characterized by its lack of continental boundaries, with its relative limits defined by major ocean currents. The main objective of this thesis is to consolidate the current research on feeding ecology of fish in the oligotrophic sea waters, with a focus on describing the food webs and species composition of pelagic organisms, along with their interrelationships. To comprehend and illuminate these interactions, various pre-existing data obtained through stable isotope analysis (15 N and 13 C) are employed to determine food web structure and trophic positions. Fluctuations in these values within food webs may provide insights into both natural and anthropogenic influences. Key words: The Sargasso sea, feeding ecology, trophic interactions, food web, stable isotopes
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Feeding ecology of bats in the eastern Mediterranean
Žďárská, Lenka ; Andreas, Michal (advisor) ; Gajdošík, Martin (referee)
This work gives an overview of the composition of the diet of bats in the eastern Mediterranean and the Middle East, discusses the structure of bat communities in different bioregions of the area in terms of hunting strategies and resource partitioning and last but not least, how echolocation and morphological characteristics of bats affect the composition of the diet. Although some samples were relatively small therefore it is necessary to look soberly at their informative value, and thus their importance is undeniable. The study in some cases provides completely the first information regarding the composition of diet in several species. Asellia arabica mainly catches Coleoptera (Scarabaeidae), Triaenops persicus hunts Lepidoptera, but Heteroptera, Coleoptera (Scarabaeidae) and Orthoptera too, while Triaenops parvus is a specialist in hunting Lepidoptera. Rhinopoma muscatellum hunts mainly Formicoidea, followed by Coleoptera (Melolonthinae) and Heteroptera, Rhinopoma hadramauticum hunts Formicoidea. Lepidoptera of different size, Heteroptera and Coleoptera are the prey of Chaerephon nigeriae. Pipistrellus hanaki has a wide niche breadth as other species of the genus Pipistrellus. In this study Brachycera, Auchenorrhyncha and Coleoptera primarily occurred in its diet. Not yet described species of...
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Potravní ekologie koní v kontextu ochranářského managementu krajiny
HÁJKOVÁ, Pavlína
This thesis provides a review of knowledge available on wild and feral horse feeding ecology, habitat preferences, competition overlap with other herbivores and their impact on vegetation. In summary, horses appear valuable for management of grasslands, but less suitable for regulation of shrubs and trees, especially when they are compared to cattle and cervids, which are more able to eliminate woody plants. Together with a tabular overview of literature on feeding ecology and plant taxa eaten by horses in the Holarctic realm, an optimalized protocol is provided to facilitate proper field collection of data about the feeding ecology and behavioral repertoire in large ungulates.
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Feeding ecology of freshwater Heteroptera (Nepomorpha)
Šretrová, Martina ; Sacherová, Veronika (advisor) ; Kment, Petr (referee)
This bachelor thesis focuses on the aquatic Nepomorpha living in freshwater, especially on the most common representatives from families, which we can find in the Czech Republic. The main theme of this work is the mapping of the feeding ecology of water-bugs. Various feeding strategies can be observed, such as phytophagy, carnivory and omnivory. The most important strategy used by most water-bugs is predation. This behavior is related to morphological adaptations, such as modifications of the mouthparts and forelegs. Ways of obtaining and processing prey are described in detail. A special chapter is dedicated to the Corixidae family, which differs morphologically. Also the importance of predatory water bugs in the ecosystem is discussed here.
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Feeding ecology of freshwater Heteroptera (Nepomorpha)
Šretrová, Martina ; Sacherová, Veronika (advisor) ; Kment, Petr (referee)
This bachelor thesis focuses on the aquatic Nepomorpha living in freshwater, especially on the most common representatives from families, which we can find in the Czech Republic. The main theme of this work is the mapping of the feeding ecology of water-bugs. Various feeding strategies can be observed, such as phytophagy, carnivory and omnivory. The most important strategy used by most water-bugs is predation. This behavior is related to morphological adaptations, such as modifications of the mouthparts and forelegs. Ways of obtaining and processing prey are described in detail and the influence of predators on their prey is discussed. A special chapter is dedicated to the Corixidae family, which differs morphologically and ecologically from other families.
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Niche Partitioning in Tropical Birds
Petruf, Miroslav ; Sedláček, Ondřej (advisor) ; Exnerová, Alice (referee)
in English Niche partitioning is a process that allows species to coexist by minimizing competition. Niches get narrow with growing habitat heterogeneity, which is evident in tightly packed tropical communities. Closely related species exhibit a high niche overlap, which intensifies competition for resources in their sympatry. Such birds avoid competitive exclusion by foraging using different methods or in different strata. Character displacement makes sympatric species diverge in foraging niches as well as in morphology, allowing specialized species to access private resources. Tropical birds in seasonal environments tend to occupy different niches in the wet and in the dry season, based on the availability of resources in their preferred habitats. Resource subdivision in sympatric members of an ecological guild usually depends on body-size- determined dominance. Territoriality may depend on the costs and benefits of defending resources, which may change seasonally. Dominance statuses vary within populations of the same species, too, promoting intra-specific niche partitioning. Within-species differences in foraging can also be the result of sexual dimorphism or differences in reproductive roles. Moreover, intra-specific differences in foraging may also explain the partial migration of some...
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Feeding ecology of the stone marten (Martes foina) in the Czech Republic
Nováková, Lucie ; Vohralík, Vladimír (advisor) ; Červený, Jaroslav (referee)
The food of the stone marten (Martes foina) was studied in synantrophic enviroment in four localities. Localities were choosen with the aim to follow an urbanization gradient from the center of the city, through its periphery to small villages. The composition of a diet was studied by non-invasive method, by analysis of faeces. Macroscopic remains of the food were divided into eleven categories (mammals, birds, bird eggs, fish, unidentified vertebrates, invertebrates, fruits, vegetative plant parts, anthropogenic material, stones and unidentified remains). 104 different animal and plant taxa were identified. There was often found anthropogenic material. Differences in the diet according the type of enviroment as well as seasonal changes were investigated by comparing of frequency of occurrence and procentual weight of remains. There were found differences between marten's food in urban and rural enviroment, especially as concerned the categories mammals, birds and fruits. Consumption of mammals follows the urbanization gradient, in urban enviroment it is the lowest, in rural localities it is higher. On the contrary, bird frequence was higher in urban environment, in rural enviroment it was lower. Weight of fruit remains was higher in rural localities than in urban ones. There were also seasonal...
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Feeding ecology of bats in the eastern Mediterranean
Žďárská, Lenka ; Andreas, Michal (advisor) ; Gajdošík, Martin (referee)
This work gives an overview of the composition of the diet of bats in the eastern Mediterranean and the Middle East, discusses the structure of bat communities in different bioregions of the area in terms of hunting strategies and resource partitioning and last but not least, how echolocation and morphological characteristics of bats affect the composition of the diet. Although some samples were relatively small therefore it is necessary to look soberly at their informative value, and thus their importance is undeniable. The study in some cases provides completely the first information regarding the composition of diet in several species. Asellia arabica mainly catches Coleoptera (Scarabaeidae), Triaenops persicus hunts Lepidoptera, but Heteroptera, Coleoptera (Scarabaeidae) and Orthoptera too, while Triaenops parvus is a specialist in hunting Lepidoptera. Rhinopoma muscatellum hunts mainly Formicoidea, followed by Coleoptera (Melolonthinae) and Heteroptera, Rhinopoma hadramauticum hunts Formicoidea. Lepidoptera of different size, Heteroptera and Coleoptera are the prey of Chaerephon nigeriae. Pipistrellus hanaki has a wide niche breadth as other species of the genus Pipistrellus. In this study Brachycera, Auchenorrhyncha and Coleoptera primarily occurred in its diet. Not yet described species of...
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Crayfishes as a prey
MAN, Milan
Due to the increase in the number of non-native species of crayfishes and their presence on more and more localities, there is the possibility of their elimination using predatory fish species. The length relationships between a prey and a predator could clarify this possibility. The aim of this bachelor thesis was to develop high quality literary review about the incorporation of crayfish into the food chain and processing samples of a perch (Perca fluviatilis) from a locality with an occurrence of juvenile crayfishes (Astacus astacus). I wanted to verify the possibility of a perch predation on juvenile crayfish individuals. However, only three crayfishes were found in the analyzed perchs. After a very low percentage of crayfishes in the analyzed perchs, a laboratory experiment was carried out with young of the year of signal crayfish (Pacifastacus leniusculus) and perchs. Unfortunately, this experiment ended unexpectedly. The crayfishes were served to perchs, but the fishes showed no interest in them throughout the experiment. The results of food analysis show, that smaller perchs are able to eat crayfish, but they are not a sought-after component of their diet. In this case, the low frequency of crayfishes in the diet was caused by enough other food (insect larvae) and also the number of shelters in the pond, where the crayfishes were reared. In the experiment, I unfortunately failed to confirm the positive relationship between a perch as a predator and a juvenile crayfish as a prey. However, the conclusions of the other studies on the use of larger perchs show the preference and high frequency of occurence of juvenile crayfishes in their diet.
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