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Predation risk and habitat complexity modify intermediate predator feeding rates and energetic efficiencies in a tri-trophic system
KOLÁŘ, Vojtěch
Many species show behavioural and physiological responses to predation risk, with important implications for their individual growth and development, but these responses may be context dependent. The goal of this study was to measure feeding and metabolic rates of intermediate invertebrate predators under different levels of predation risk and abiotic conditions to understand how they might affect their energetic efficiency, i.e. the ability to utilize available resources for individual growth. We ran laboratory experiments with larvae of three odonate species representing intermediate predators exposed to three levels of predation risk (none, visual cues, and visual and chemical cues) and two levels of habitat complexity (present vs. absent artificial submerged vegetation). We show that the response of intermediate predators to predation risk and its consequences for energetic efficiency are species specific and likely determined by their foraging and defense traits and their habitat domains.
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Ecology of top fish predators, European catfish and asp, with consequences to fish communities
ŠMEJKAL, Marek
The dissertation thesis focuses on predator ecology in artificial water bodies. Paper I deals with the importance of chemical cues for predator-prey interactions in an aquatic environment. Here, I demonstrate that the ability to detect chemical cues represents a survival benefit for prey species. Paper II points out gillnet methodological bias, which may have subsequent repercussions in field evaluation of a predator's presence and assessment of larger fish abundance in general. Papers III and IV focus on asp Leuciscus aspius spawning grounds. In Paper III, I demonstrate how males maximize their spawning chances by early arrival and in Paper IV, I evaluate the predation pressure of asp prey, Alburnus alburnus, directed on asp eggs.
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Recognition of predators in vertebrates: innated or learned?
Antonová, Kateřina ; Fuchs, Roman (advisor) ; Adamová, Dana (referee)
Predator recognition is the prerequisite for antipredatory behaviour. The ability to recognize predator may be inborn or acquired. The mammals as well as majority of birds have common care for brood. Many of both groups form more or less complicated societies. All those support naive individuals in acquiring knowledge of predators through the social learning that is not as risky as learning through experience. Studies of inborn or acquired recognition as applied by mammals and birds may bring generalized closures about various learning forms by both of these groups. Surprisingly, no systematic observations were made to the matter. As recent studies show, the naive mammals and birds may recognize predators, no conforming results were presented yet. Obviously, the recognition is depending on the incentives presented. Alive predator invokes more intensive response than any model, while the olfactory efficacy depends on the carrying medium. The recent studies in an integrant part neither allow to determine experimental precision. To do so, much larger volume of predators and controls should be made. However, studies of the kind are rare. Studies of mammal and birds' inborn and acquired predator recognition still remain the attractive research theme. Keywords: predator, recognition, innated, learned,...
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The impact of predation risk and habitat complexity on trophic interactions in aquatic habitats
KOLÁŘ, Vojtěch
The thesis results of two laboratory experiments focusing on the impacts of predation risk, prey density and habitat complexity on predator-prey interaction strengths and predator metabolic rates, complemented by a brief review of the subject. The experimental system used in the first experiment consisted of cladoceran prey, larvae of three dragonfly species (Sympetrum sanguineum, Libellula quadrimaculata, Ischnura cf. elegans) as intermediate predators, and larvae of a large dragonfly species (Aeshna sp.) as a top predator. The second experiment of investigated how predation risk influences metabolic rates of the intermediate predators.
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