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Phenotypic plasticity and functions of morphological antipredator structures in genus Daphnia
Brož, Vojtěch ; Petrusek, Adam (advisor) ; Šorf, Michal (referee)
Predator-induced defence mechanisms are widespread among animals, plants and other organisms. One of the model taxa for research of this phenomenon is the cladoceran genus Daphnia, as its species of this genus possess many morphological, behavioural and other defence mechanisms. Among the most conspicuous examples are specialized antipredatory structures. In many species, the presence of a helmet, i.e. a head expansion that serves as a protection from various invertebrate predators, can be found. A specific case is represented by two species in which the helmet is involved in protection from planktivorous fish. Another, rather widespread defence is the formation of neckteeth, a specialized structure against predatory larvae of phantom midge (Chaoborus spp.). There are also other less frequent antipredatory structures such as a crest or a "crown of thorns". This thesis summarizes the available information on the distribution, evolution, function and mechanisms of induction of these inducible morphological defence structures.
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Diversity of zooplankton of Tatras lakes in space and time
Čablová, Radka ; Černý, Martin (advisor) ; Šorf, Michal (referee)
This thesis is the first of its kind that evaluates the species composition, species richness and species abundance of zooplankton in littoral samples of 90 Tatras lakes (Western and High Tatras of Slovakia and Poland) collected in September 2004 in the context of environmental parameters of lakes and spatial relationships of individual lakes. The most frequently occurring species in the Tatras lakes in 2004 were also evaluated in terms of their occurrence in the lakes a century ago (Minkiewicz 1914, 1917 and Lityński 1913, 1917), during the period of acidification (Ertl & Vranovský 1964, Ertl et al. 1965, Hrbáček et al. 1974, Stuchlík et al. 1985) and during the period of recovery of the lakes from acidification (Hořická et al. 2006, Sacherová et al. 2006). Relationships between variables were analysed using Poisson regression, cluster analysis with multinomial regression, canonical correspondence analysis, Mantel tests and multiple negative binomial regression. Using analyses, lakes were divided into four clusters (A, B, C, D). Each cluster consisted of lakes with the same environmental and spatial factors and similar species composition. Thirteen zooplankton species (Acanthocyclops vernalis, Acroperus harpae, Alona affinis, Arctodiaptomus alpinus, Ceriodaphnia quadrangula, Cyclops abyssorum...
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Habitat preferences of the members of the family Chydoridae (Crustacea, Cladocera)
Zimová, Tereza ; Sacherová, Veronika (advisor) ; Šorf, Michal (referee)
This thesis is a literature review of ecological niche of some species of Cladoceran family Chydoridae. The aim of this work is to summarize the knowledge about the occurrence of species in various types of environments and what are their preferences or see which factors are limiting for them. This work is focused on the type of habitats in which they are found, the trophic state of water and pH. It also mentions to a lesser extent environmental factors such as concentration of calcium and water depth, which might also influence the niche choice of these species. Species can be divided into opportunists with a wide niche and specialists with a narrow one, yet a large proportion of species have a wide tolerance to most environmental factors. Key words: Chydorids, niche, habitat, macrophytes, open water, pH, trophic state, depth, calcium
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Recovery of zooplankton community from the acidification in mountain lakes
Bartošíková, Martina ; Sacherová, Veronika (advisor) ; Šorf, Michal (referee)
Mountain Lakes in Bohemian forest are currently undergoing a process of acidification. In spite of the rapid improvement of chemistry, the biological recovery is considerably delayed. This state may be due to a number of factors, such as persistent periodic pH fluctuations and hence increased aluminum leaching, phosphorus limitation, resistance of acid-tolerant communities, or limited opportunities for spreading from surrounding sites or damage to the egg bank. With the delay in improving the chemical composition of water gradually comes the improvement of the biological state, which manifests in the first phase by increasing the abundance of the existing species, in the second by increasing the number of species. In addition to the fish, it seems that the largest filtering dwarfs of the genus Daphnia are returned. In spite of their efforts to accelerate their return in the natural experiment by repatriating the species Cyclops abyssorum and Daphnia longispina to Plešné Lake in 2004, the wildebeests did not enjoy the new locality. Still, after almost ten years, individual individuals of this kind were found in lake litoral. This diploma thesis builds on the research of the Bohemian forest lakes, which is going on for almost 150 years. The zooplankton's response to changes in chemistry was studied...
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Optimalization of mixed goods pickup and delivery
Šorf, Michal ; Skočdopolová, Veronika (advisor) ; Dvořák, Marek (referee)
This thesis is focused on the use of linear models in the real world. Its main aim is to devise a mathematical model for a specific problem which is repeatedly encountered by the company Pospíchal s.r.o. and also to find an optimal solution with the help of this model. The thesis is based on basic distribution problems, such as the travelling salesman problem or the vehicle routing problem, which I subsequently modify into the required form. The thesis is divided into three main parts. The first one focuses on the description of basic models that will be modified in the last part. The following part deals with a brief description of the company already mentioned above that provided data without which this task could not be demonstrated in practice. The final part includes a detailed analysis of the given task, formulation and description of the mathematical model, which was created on the basis of specific requirements of the company. There is also a comparison of actual results from practice with optimal results.
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Zooplankton response to a change of water chemistry and amount of food during the recovery of lakes from acidification
Bartošíková, Martina ; Stuchlík, Evžen (advisor) ; Šorf, Michal (referee)
Anthropogenic acidification has affected assemblages in thousands of lakes in North America and Europe. It turned out that, during the acidification, the number of zooplankton changed and also the species composition of their assemblages, at some sites there was also the total disappearance. The main reason was a decrease of pH, wash out toxic aluminium and a change of trophic status. The rate and extent of biological recovery after restoring the pH in acidified lakes varies considerably across regions. Recovery of aquatic communities is significantly lagging behind the recovery in chemistry. Some zooplankton species are nonetheless able to quickly colonize recuperating ecosystems and in many acidified lakes again started to appear native species that have disappeared during acidification. The return of indigenous species, however, can be blocked acid-tolerant occurrence of species after species extinct occupied empty niches. Zooplankton can be affected by water chemistry directly, but also indirectly by the quality and quantity of food. An important factor is the possible spread of colonizing species. However, the relative roles of these factors in regulating recovery may be difficult to determine. Key words: zooplankton, acidification, water chemistry, aluminium toxicity, phytoplankton
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Different effects of planktonic invertebrate predators and fish on the plankton community in experimental mesocosms
ŠORF, Michal
The impact of fish and cyclopoid copepod predation on zooplankton communities was evaluated using large-volume mesocosms (depth 9.5 m; volume 13 m3) in the Římov reservoir (Czech Republic). Two yearling roach and perch individuals introduced into mesocosms represented the fish treatment, which was compared to cyclopoid copepods (initial abundance of 2 ind.L-1) and a control with no initial addition of predators. Our results clearly support the hypothesis that planktivorous fish feeding leads to the suppression of large-bodied cladocerans. In the presence of fish, the cladoceran community changed from a dominance of large-bodied Daphnia spp. at the beginning to dominance by the smaller Bosmina longirostris at the end of the experiment. The overall strong effect of fish over cyclopoid predation suggests the main role of fish predation in the forming of zooplankton communities and in turn impacting phytoplankton biomass in mesocosms.
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The impact of fish and planktonic invertebrate predation on zooplankton in experimental mesocosms
ŠORF, Michal
This thesis focuses on the effect of fish and invertebrate predation on zooplankton in deep reservoir and shallow lakes. Mesocosms were used to evaluate the separated and combined effect of both type of predation. An appropriate mesocosm approach was modified and used in the Římov reservoir. The last part is dedicated to the effects of predation on zooplankton in contemporary changing environment, mesocosm experiment with different temperature and nutrient levels was conducted.
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