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Reintroduction of a copepod species Cyclops abyssorum (Crustacea) and its impact on zooplankton in Plešné Lake
Křenová, Radka ; Sacherová, Veronika (advisor) ; Vrba, Jaroslav (referee)
Abstract Plešné Lake is a small glacial lake in the Bohemian Forest. In the 1980th, it was heavily influenced by an acification event caused by severe atmospheric pollution. Due to some extreme parameters in the water chemistry (mainly low pH and high concentration of toxic aluminum compounds) several zooplankton species got extinct. Among these, two species important in lakes food web: Daphnia spp. and Cyclops abyssorum. They, however, survived the acidification period in one of the Bohemian Forest Lake: Prášilské. Although recovery of lakes from acidification is usually followed by return of some species or colonization by others, recolonization of Plešné Lake is assumed to be very slow or impossible from external sources thanks to the remote position of the lake. Therefore in the fall of 2004 two zooplankton species (Daphnia longispina and Cyclops abyssorum) were artificially reintroduced into Plešné Lake. In the course of 4 years that followed only Cyclops abyssorum appeared in the lake, Daphnia longispina was not recorded. My thesis focuses on several aims. First, I evaluate the development of C. abyssorum population. Second, I studied the competition between C. abyssorum and another copepod species - Heterocope saliens, acidotolerant species which never disappeared from the lake. Third, I...
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Phylogeny, phylogeography and taxonomy of selected members of the family Bosminidae
Faustová, Markéta ; Sacherová, Veronika (advisor) ; Hudec, Igor (referee) ; Schwenk, Klaus (referee)
Phylogeography, taxonomy, and systematics of chosen members of family Bosminidae Abstract of Ph.D. Thesis MSc Markéta Faustová Supervisors: RNDr. Veronika Sacherová, Ph.D. - Charles University in Prague, Czech Republic Dr. Derek J. Taylor, Ph.D. - New York State University at Buffalo, U.S.A. For their life cycles, phenotypic plasticity, presence of sibling species and worldwide distribution, cladocerans are useful organisms for evolutionary studies with the aim to understand mechanisms of speciation, adaptive radiation, and polymorphism. While members of the genus Daphnia (family Daphniidae) became an iconic model in such studies, members of the family Bosminidae posses comparably interesting set of characteristics that could help to elucidate speciation mechanisms. In particular, members of the genus Eubosmina are known for extreme levels of phenotypic plasticity, especially in the Circumbaltic region, which puzzled the taxonomy and confused relationships of all described morphotypes since the first Eubosmina was described in 1857. The presented thesis explores genetic and morphometrical relationships with the aim to clarify how closely related all the described morphospecies are, to find out if there are some reproductive barriers and how strong these barriers are, how is the present-day structure of...
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Foraging strategies of invertebrate predators in mountain lakes
Hrdličková, Jana ; Sacherová, Veronika (advisor) ; Hořická, Zuzana (referee)
In mountain lakes, which were affected by acidification in the past or in the present, invertebrate species have become top predators and they influence the whole community. This thesis deals with foraging strategies of three of these predators, Cyclops abyssorum and Heterocope saliens (Crustacea: Copepoda) and Glaenocorisa propinqua (Insecta: Heteroptera) in the model localities Černé lake, Plešné lake and Prášilské lake. The main aim was the determination of food composition and food preferences of these predators. The quality and quantity of consumed food I investigated with a microscope using a method which has not been published yet. To make a microscope preparation I used Potassium hydroxide or Lactic acid in order to dissolve soft organic matter, so that the chitinous particles were well visible. The found food of animal origin was subsequently compared with the prey availability with the use of Jacobs' index. In addition to this research, a feeding experiment with G. propinqua was carried out. The food of all the invertebrate predators was dependent on food availability or eventually on the season of the year. G. propinqua mostly preferred as a prey members of Daphniidae family and then the species Polyphemus pediculus (Cladocera), if they were available (Prášilské lake). In Plešné lake,...
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What is the key factor driving the expansion of invasive bentic invertebrates in the czech rivers?
Kolářová, Lucie ; Tátosová, Jolana (advisor) ; Sacherová, Veronika (referee)
The main part of the thesis discusses the occurrence and spreading of non - indigenous species of bentic freshwater invertebrates in the Labe River and it is based on long - term physical, chemical and biological data provided by Povodí Labe, state enterprise. Our results show a decrease in the concentration of nutrients at monitored stretch of the Labe River during the time period between years 2000 and 2011. The relative richness of non - indigenous species in benthic communities was analysed by TCI (Taxonomical Contamination Index), while their relative abundance was analysed by ACI (Abundance Contamination Index). Values of those two indexes increased during the time period between years 1998 and 2012. A detailed analysis is focused on four species - Dikerogammarus villosus, Corbicula fluminea, Jaera istri and Corophium curvispinum. The highest ACI value, as well as the total abundance of D. villosus, C, fluminea and J. istri, has been found at the Velké Březno site. Different values of TCI and ACI indexes and different abundances of specific invasive species can be caused by diverse environmental conditions characterising the studied sites. Significant differences between physical - chemical parameters measured at specific sites has been shown by the Kruskal - Wallis test (α = 0, 05). Only the...
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Genetic delineation of species in cladocerans (Crustacea, Cladocera)
Korytová, Nikola ; Sacherová, Veronika (advisor) ; Korábek, Ondřej (referee)
Cladocera (Crustacea, Branchipoda) are a diverse group of planktonic crustaceans. There are many cryptic species which form species complexes. Families Daphniidae and Chydoridae who live in water bodies around the whole world, have not completely resolved taxonomy so far. Mophological and genetic analyses are used for identifying species. It is often preferable to study their genetic distances, because they frequently hybridize. The genetic markers (DNA sequences that are unique to each species) are used for the genetic analysis of taxa. Although mitochondrial genes provide better results on a species level, nuclear genes may also be used. Cytochom c oxidase subunit I (COI), 12S and 16S rDNA are the most used mitochondrial genes. However, the situation in families Daphniidae and Chydoridae is complicated and assigning precise genetic distance for delineation of the species is not easy, although these genes allow well-supported phylogenetic trees. The future studies should examine more closely the dating events and create molecular clocks, especially for the family Chydoridae, which is often neglected despite its species diversity. Key words: Daphniidae, Chydoridae, genetic markers, COI, 12S rDNA, 16S rDNA
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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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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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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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