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Taxonomic position, phylogenetic relationships and metal resistance of green algae dominating in phytoplankton of two acid lakes
Barcyte, Dovile ; Nedbalová, Linda (advisor) ; Hašler, Petr (referee)
The aim of this diploma thesis was to reveal the taxonomic position and phylogenetic relationships of the dominant planktonic algae in two acid metal-rich lakes (Hromnice Lake and Plešné Lake, Czech Republic) and to compare these isolates with other closely related strains with the focus on the tolerance to various toxic metals (Cr, Al, Cu, Mn, Zn, Hg). The phylogenetic analyses showed that both strains belong to species Coccomyxa simplex. It was the first evidence that specifically this species is capable to become the dominant phytoplankton alga in the extreme environment of acid lakes with increased supply of phosphorus. Based on 18S rDNA analysis, four independent phylogenetic lineages were revealed within the genus Coccomyxa with three of them containing isolates from acid freshwaters. Furthermore, new strains of the recently described species Coccomyxa polymorpha were found growing in various chemical solutions. The toxicity test revealed that Coccomyxa simplex strains isolated from Hromnice and Plešné lakes did not show any peculiar resistance to increased metal concentrations. A significantly strain-specific response was recorded in case of aluminum, however, it was not related to the concentration of this metal in the original habitat. The ability to thrive in extreme habitats is probably...
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Identification and ecophysiology of coccoid green algae dominating in ice-covered lakes on James Ross Island (NE Antarctic Peninsula)
Mihál, Martin ; Nedbalová, Linda (advisor) ; Hodač, Ladislav (referee)
The aim of this study was to assess the phylogenetic relationships, morphological and ecophysiological characteristics of three strains of coccoid green algae from Antarctica. The strains A and B are planktonic algae dominating in ice-covered lakes on James Ross Island (NE Antarctic Peninsula). The third strain (Ankistrodesmus antarcticus CCAP 202/25) was originally isolated from green ice from the Balleny Islands (Ross Dependency) and its description has been based only on morphological features. According to the phylogenetic analyses of 18S rDNA, ITS2 secondary structure and cell morphology, the strains A and B belong to one species of the genus Monoraphidium (Chlorophyta, Sphaeropleales, Selenastraceae) that should be described as new in the future. It is the first evidence that coccoid green algae are capable to become the dominant primary producer in the extreme environment of Antarctic lakes with extensive ice-cover. The strain CCAP 202/25 is closely related to Monoraphidium griffithii (type species of the genus Monoraphidium) suggesting its incorrect classification. All the strains were able to grow in a wide temperature gradient: 1-20 řC (A and B) and 1-30 řC (CCAP 202/25). Low light requirements reflected their original habitat. Together with relatively high growth rates and high content...
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Crustaceans of Antarctic lakes - past and present status
Pokorný, Matěj ; Sacherová, Veronika (advisor) ; Nedbalová, Linda (referee)
Antarctic continent is one of the most severe regions on Earth and it is characterized by low annual temperatures, low precipitation, extensive ice cover and low energy input from the Sun. Nevertheless its lakes host not only microbial communities and protists but in many cases even in the most extreme localities also metazoans, especially rotifers and crustaceans. For at least the last 15 million years Antarctica has experienced massive glaciations that shape the distribution of organisms on this continent. Although it was originally thought that freshwater animals did not survive Quaternary glaciations in situ but migrated to milder regions in the north, nowadays it appears that at least in some cases it is not true. Direct evidence of survival of rotifers (Notholca sp.) and crustaceans (Daphniopsis studeri) in Antarctica was given by paleolimnological studies that were carried out in the Larsemann Hills and circumstantial evidence for permanent survival of crustaceans in Antarctica (e.g. Gladioferens antarcticus) is also growing. Antarctica is currently inhabited by about 14 species of freshwater crustaceans but recent climate changes and rapid warming of Antarctic Peninsula will probably lead to changes in the distribution of some species (e.g. Bockella poppei, Branchinecta gaini) that could, combined...
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Stress resistance of polar hydro-terrestrial algae Zygnema spp. (Zygnematophyceae, Streptophyta)
Pichrtová, Martina ; Němcová, Yvonne (advisor) ; Nedbalová, Linda (referee) ; Karsten, Ulf (referee)
Filamentous green microalgae of the genus Zygnema belong to the most common primary producers in the polar hydro-terrestrial environment. In such unstable habitats, organisms are subject to various stress factors, e.g., freeze-thaw cycles, desiccation and high irradiation levels. However, the stress resistance mechanisms that enable Zygnema spp. to thrive in this extreme environment are only partially understood. Therefore, polar Zygnema spp. were examined under various stress conditions using both field samples and cultures. Moreover, molecular phylogeny methods were applied that provided first insights into the diversity of polar Zygnema. Sequencing of the chloroplast gene rbcL revealed several different Zygnema genotypes and, surprisingly, one Zygnemopsis sp. with vegetative Zygnema sp. morphology. First set of experiments examined the effects of UV exposure. It turned out that polar strains of Zygnema produce phenolic substances as UV screens. These substances are most likely stored in vacuoles and other vesicles at the cell periphery, providing protection for other organelles. In the next study, Zygnema spp. were investigated under natural conditions in the Arctic. At the end of summer, the cells gradually lose their typical vegetative appearance (with large vacuoles and stellate chloroplasts)...
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Taxonomy, ecology and biogeography of aquatic and limno-terrestrial diatoms (Bacillariophyta) in the Maritime Antartic Region
Kopalová, Kateřina ; Nedbalová, Linda (advisor) ; Sabbe, Koen (referee) ; Jüttner, Ingrid (referee)
Diatoms (Bacillariophyta) are one of the most diverse algal groups in the Antarctic Region and play a dominant role in almost all freshwater and terrestrial ecosystems. Despite this overall occurrence, little is known about the diversity, ecology and biogeography of this group in the Maritime Antarctic Region. The main objective of this thesis is therefore to define the taxonomical, ecological and biogeographical characterisation of aquatic, semi- aquatic and moss-inhabiting diatom communities from two islands in the Maritime Antarctic Region: James Ross Island and Livingston Island, located on opposite sides of the Antarctic Peninsula. In this study, a total of 250 samples from three different habitat types (lakes, streams & seepage areas and mosses) from Byers Peninsula (Livingston Island) and Ulu Peninsula (James Ross Island) have been analysed. Using light and scanning electron microscopy, a rather diverse diatom flora composed of 178 taxa, belonging to 43 genera has been identified. Although even until recently, it was generally accepted that the Antarctic diatom flora was mostly composed of cosmopolitan taxa, several new species could be described as a new for science during this PhD study (a reflection of this work is presented in chapters 2 & 3 and in Appendices). Habitat type and...
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Diversity, ecology and ecophysiology of snow algae
Mikešová, Lenka ; Nedbalová, Linda (advisor) ; Kvíderová, Jana (referee)
Permanent and temporary snow cover in polar and mountain areas is a very extreme habitat. However, there are organisms that inhabit this environment. Green algae of the order Chlamydomonadales (Chlorophyta) belong among the important representatives of cryoseston, which are known from polar and mountain regions around the world. These organisms, which occupied the snow environment probably secondarily, developed different ecophysiological adaptations required for the successful survival in extreme conditions. Low temperatures and high levels of radiation are the main extreme factors that organisms must cope with. The most important survival mechanisms include the adaptation of life cycles (such as of the shifts between resistant stages and moving vegetative stages), accumulation of secondary carotenoids, changes in fatty acid composition of membranes and lowering of growth temperature optima in some species. These adaptations together with the study of diversity represent at present the main subjects of research of snow algae.
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Acidophilous cyanobacteria and algae
Macholdová, Markéta ; Nedbalová, Linda (advisor) ; Medová, Hana (referee)
Due to natural processes and human activity extremely acidic habitats, whose pH does not exceed 3.0, are formed on Earth. These are especially areas affected by the acid mine drainage (AMD) and of volcanic activity. The biodiversity of these habitats is greatly reduced, but there are microorganisms that are very well adapted to such extreme conditions. These organisms are termed as acidophilic. Cyanobacteria and algae are the only primary producers at extremely acidic sites and thus play a crucial role in these ecosystems. Although they must overcome several problems that are associated with such an environment (excess of H+ ions, increased concentrations of heavy metals), they developed a range of ecophysiological adaptations and life strategies that allow them to inhabit it. These are mainly the ultrastructural changes in the cell membranes, special metabolic processes and the production of special substances and enzymes. Acidophilic species are present across almost all taxonomic groups of cyanobacteria and algae. Interest in acidophilic organisms has increased in recent decades due to their potential use in biotechnology. Knowledge of their taxonomy, ecology and ecophysiology can also be used in paleobiology and exobiology.
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Phytoplankton succession in experimental ponds
Zelený, Jakub ; Nedbalová, Linda (advisor) ; Bílý, Michal (referee)
1 Abstract Newly created habitats present a unique model environment for the study of succession and related processes. Their relative isolation and the possibility to observe community assembly dynamics from the very beginning makes these experiments repeatable under controlled conditions. Planktic organisms with short generation cycles represent useful model organisms for the research of succession and related features like the influence of environmental variables or priority effect. The thesis aims at describing the succession of phytoplankton in a set of 20 experimental ponds, where phytoplankton structure and environmental parameters have been observed for six years (2007 ̶ 2012). The ponds are located in Liběchovka River-bed, which is a part of Kokořínsko Protected Landscape Area. The target locality is protected by the Ramsar agreement as a habitat for pulling birds and amphibians. We used classical and multidimensional statistical methods (PCA, DCA, CCA) to analyse the variability in species composition and shifts in environmental variables. Metacomunity structure indices (α,ß,γ) showed a decrease of α diversity accompanied by an increase in ß diversity over the study period, which have been caused by a marked differentiation of communities in 2011 ̶ 2012. γ diversity peaked in the middle of the...
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