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What hinders the recovery of zooplankton communities in acidified lakes?
Jůzek, Václav ; Sacherová, Veronika (advisor) ; Kaňa, Jiří (referee)
Acidification of soil and water environments, which emerged with the beginning of the Industrial Revolution, became a major ecological problem of the 20th century. The increase in emissions and subsequent deposition of acidifying substances into the environment has caused a significant decline in abundance and biodiversity of aquatic organisms in European and North American lakes. Emissions causing acidification have been reduced since the 1990s, yet aquatic ecosystems are not returning to their pre-acidification state. This thesis concludes the factors affecting the course of chemical and biological recovery of aquatic ecosystems affected by atmospheric acidification. The reviewed literature shows that communities newly established in acidified waters seek a new ecological equilibrium, and thus recolonization of native species is not limited by merely unsuitable water chemistry itself. Bohemian forest lakes have also been affected by acidification and are now in the process of recovering. The main factors affecting the recovery of natural zooplankton communities in lakes are high aluminium concentrations, periodic pH fluctuations, catchment characteristics and, more recently, climate change and associated bark beetle-induced tree dieback. Keywords: acidification, recovery, zooplankton, Bohemian...
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Invasive zooplankton species in Europe and factors influencing their occurence
Klečková, Barbora ; Sacherová, Veronika (advisor) ; Šorf, Michal (referee)
In Europe, there are at least 8 invasive species of freshwater zooplankton: rotifers Kellicottia bostoniensis (Rousselet, 1908) and Lecane decipiens (Murray, 1913), copepods Acanthocyclops americanus (Marsh, 1892), Boeckella triarticulata (Thomson, 1883) and Skistodiaptomus pallidus (Herrick,1879), and cladocerans Pleuroxus denticulatus Birge, 1879, Daphnia ambigua Scourfield, 1946 and Daphnia parvula Fordyce, 1901. These invasive species must face various combinations of factors in non-native environments, which can influence their occurrence,andtheir presence canhave negative impacts onnative communities in some cases. The most significant invasions seem to be those of species from North America. The first part of this work summarizes knowledge about these 8 species, mainly about the factors that appear to be limiting their occurrence. Among the best-studied invasive species in Europe are cladocerans Daphnia ambigua and Daphnia parvula, whose presence has been extensively studied in the Czech Republic at the turn of the 21st century. Therefore, the second part of this work also thoroughly examines the factors that may play a significant role in the colonization of waters by these species in Central Europe. Key words: European invasive zooplankton species, biotic factors, abiotic factors,...
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Reproductive modes in large Branchiopoda (Crustacea) and their effect on genetic structure of populations
Šimková, Zuzana ; Sacherová, Veronika (advisor) ; Straková, Barbora (referee)
This bachelor's thesis focuses on the influence of the reproductive systems of four groups of so-called large branchiopods (Crustacea: Branchiopoda) on genetic variability in their populations. The groups include the orders of fairy shrimp (Anostraca), tadpole shrimp (Notostraca), clam shrimp (Spinicaudata), and conchostracans (Laevicaudata). This thesis primarily examines the populations in Europe. Reproductive strategies are one of the key factors that influence the genetic variability of populations. Other factors include historical events such as the breakup of the supercontinents Gondwana and Pangea and the last ice age, along with its associated processes (such as the colonization of new habitats after the end of the last ice age, etc.) The most genetically variable populations in Europe are gonochoristic (Branchipus schaefferi, Phallocryptus spinosa, Triops mauritanicus, Leptestheria dahalacensis, and Lynceus brachyurus), followed by populations with other reproductive systems. Based on current knowledge, some gonochoristic species and species utilizing a different reproductive system are divided into multiple genetic lineages. Depending on the historical processes, these lineages were most likely separated before the last ice age. Therefore, the current geographical distribution of lineages...
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Colonisation of Central Europe by benthic frehwater crustacean Asellus aquaticus (Isopoda, Crustacea)
Střížek, Antonín ; Sacherová, Veronika (advisor) ; Špaček, Jan (referee)
Longterm climate changes are an inseparable part of the evolution of Earth. In the last few milions of years the changing of glacials and interglacials was as ordinary and regular phenomenon as changing from day to night or from spring to summer. These cycles also have similar influance on evolution of nature on Earth. Eventhough the state of nature appears to us stable for the few last human generations, the reality from the long term point of view is differnt. During these cycles, the location of climatic zones, size of glaciers, deserts, savannahs, steppes or rainforests have changed. Organisms changed locations of their areas of distribution, many nowadays widespread species were pushed into isolated local populations. This Master's thesis reveals the impact of glacial cycles on a freshwater crustacean aquatic Isopod (Asellus aquaticus). Very variable mitochondrial COI gene was sequenced within 139 individuals of this species from 62 different localities in Europe. This data were included into an extensive scope of an already known phylogeographic structure of the continent. An Aquatic Sowbug shows a quite high rate of a genetic heterogenity (maximum Nucleotide Divergence discovered is 0,132 and average is 0,016) in the area of the Czech Republic. Where there are found representatives of two...
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Spatial orientation in Odonata
Hupková, Lenka ; Černý, Martin (advisor) ; Sacherová, Veronika (referee)
The aim of this review is to evaluate and sum up an existing knowledge about spatial orientation of dragonflies, particularly at small and medium spatial scales. I deal mostly with orientation by horizontally polarized light, which belongs among the most explored field of orientation of Odonata; beside that I explore an orientation of dragonflies during the habitat selection and within their home ranges / territories. Regarding the latter, I pay an attention namely to the function of spatial landmarks, which has not been yet fully explored and offers a lot of opportunities for further research (like many other orientation topics of Odonata). I also briefly discuss an orientation of dragonflies during migrations. Besides the visual orientation I mention the orientation by olfactory sense, tough Odonata was concerned anosmic for a long time. Key words: spatial orientation, visual orientation, dragonflies, Odonata, landmarks
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Morphological and genetical variability of Chydorus sphaericus (Crustacea, Cladocera) depending on the environment
Matušková, Ludmila ; Sacherová, Veronika (advisor) ; Kořínek, Vladimír (referee)
Úvod 5 ABSTRACT Genus Chydorus or more specifically the species of Chydorus sphaericus represents an extremely tolerant freshwater organism, which occurs in littoral zone of almost all kinds of aquatic habitats all over the world. It is usually associated with submerged macrophytes or substrate and also plays a key role in food webs of both vertebrate (fish) and invertebrate predators. Not only is this species in most localities the most common chydorid, but it is quite often the most common filtering cladoceran. Moreover, due to its little morphological variation most small globular representatives of the genus Chydorus were in the past all incorrectly ascribed to Chydorus sphaericus. However, thanks to more detailed studies it was suggested that so called species Chydorus sphaericus was not in fact a single taxonomic entity, but a group of several closely related species. It is clear today that for correct taxonomic desision it is necessary to combine all ecological, morphological, and genetic methods. The aim of this study was to explore genetical and morphological variation in populations of Chyrodis sphaericus from localities representing different sets of environmental factors. Four model localities were chosen: eutrophic ponds, temporary pools, mountain lakes and waterbodies affected by mining...
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Phylogeography and genetic variation of benthic crustaceans in European inland waters
Pešek, Pavel ; Petrusek, Adam (advisor) ; Sacherová, Veronika (referee)
This thesis summarises published information about geographic distribution of genealogical lineages and genetic variability of benthic crustaceans of European continental waters, and evaluates the historical factors that affected their distribution. it is focused mainly on species for which multiple or in-depth studies have been published. A particular attention is given to crayfish of the genus Austropotamobius. Present distribution of genealogical lineages has been affected by changes in connectedness and availability of aquatic habitats. Species lineages often split in consequence to geological and climatic processes during the Tertiary, as exemplified on species complexes of Austropotamobius crayfish, species lineages of the amphipod Gammarus fossarum species complex, and the isopod Asellus aquaticus. The distribution of intraspecific lineages has been strongly affected by Quaternary cycles of glaciation, which not only destroyed many habitats by moving glaciers but also created new colonisation routes. Such routes were peri-glacial lakes, which had been used by Gammarus lacustris, or retreat of sea level, which enabled white-clawed crayfish to colonise England, and a freshwater crab to colonise Italy. Changes in sea levels are also the likely reasons for colonisation of continental waters by the...
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