|
|
Phaeocystis - a key organism in dimethylsulfoniopropionate production; ecological and physiological functions of DMSP
Füllsacková, Alena ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
Dimethylsulfoniopropionate (DMSP) is an organic sulfur compound with an important ecological and physiological functions. DMSP is a major precursor for dimethylsulfid (DMS). DMSP is produced by variety of halophytic plants and phytoplankton for the purposes of osmotic regulation, antioxidation and protection from predators. It is especially widespread among the marine phytoplankton and it is ubiquitous in the euphotic zone. DMS and DMSP are also involved in flux of carbon and sulfur. Marine emissions of DMS have a particularly important role as precursors of atmospheric sulfur-containing aerosols that influence the Earth's climate system through direct backscatter of solar radiation and through cloud formation. DMSP is produced mainly by phytoplankton, because this group of organism is very large, I'll focus on Phaeocystis. Phaeocystis is a genus of marine phytoplankton with a worldwide distribution. It has a polymorphic life cycle alternating free-living cells and colonies but develops massive blooms under the colony form. Among the 10 species, only 3 (P. pouchetii, P. antarctica, P. globosa) have been reported as blooming species. DMSP is produced intracellulary and it is released as DMS. DMS concentration is high during the growth of the cells, predation or senescence. The production of DMSP is...
|
|
|
The role of microhabitats in spatio-temporal differentiation of freshwater algal assemblages
Pusztai, Martin ; Němcová, Yvonne (advisor) ; Kulichová, Jana (referee)
This thesis deals with microhabitats in relation to the spatio-temporal differentiation of freshwater algal assemblages. Algae are defined ecologically, althought they represent a diverse polyphyletic conglomerate. Based on the available literature, type of substrate appears as a suitable representative of most freshwater microhabitats when comparing results from different studies. Influence of microhabitat may occur not only on a small spatial scale, but also on a regional scale. The importance of scale and traceability of different factors are further discussed as well as the appropriate definition of the microhabitat. Microhabitats diversity is often reflected in the spatial heterogeneity of algal assemblages. Based on the common trends in the algal life strategies, erosional and depositional substrates can be distinguished. Living substrates, especially macrophyte surfaces represent a special category of microhabitats. Algae can enter complex interactions with these living substrates.Temporal dynamics is relatively less explored in comparison with the spatial heterogeneity.
|
|
|
Elucidating the evolution and diversity of colonial chrysophytes
Pusztai, Martin ; Škaloud, Pavel (advisor) ; Siver, Peter (referee) ; Gusev, Evgeniy S. (referee)
Our current knowledge of chrysophyte diversity is still generally based on traditional morphospecies descriptions. Accordingly, sequence data exist for the minority of all described species. Consequently, several common morphotypes (e.g. Ochromonas-like flagellate) are scattered across the phylogenetic tree of Chrysophytes. It is evident that the postulated taxonomic diversity certainly does not reflect the real species richness in Chrysophytes. Moreover, recent studies on silica scaled chrysophytes (Mallomonas, Paraphysomonas, Synura) clearly demasked common problematics of (pseudo)cryptic species even within this group possessing relatively good species concept based on the ultrastructure of silica scales and bristles. Contrary, most of chrysophytes are naked flagellates forming stomatocysts as the only solid structure in their life cycles. While single-celled Ochromonas and Spumella were recently revisited using molecular genetic techniques, Uroglena-like colonials remained untreated. Therefore, the main objective of this thesis was to provide a modern taxonomic revision of the widespread colonial chrysophytes causing conspicuous seasonal massive population booms, Synura s.l. and Uroglena s.l., by a polyphasic approach encompassing molecular phylogeny, morphology/ultrastructure and ecology....
|
|
|
Adaptation mechanisms to wide salinity gradient in algae; transitions between marine and freshwater environments in chrysophytes
Knotek, Petr ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
The transition from the marine to the freshwater environment and vice versa is a key event in the evolution of organisms. Although these transitions are relatively rare from an evolutionary point of view, most large groups of organisms have undergone this event at least once. The marine and freshwater environment differs in many aspects, especially salinity. During the transition between these two environments, the organisms are forced to overcome a significant salinity gradient and adapt to changes in the osmotic potential. However, biotic factors also play an important role, especially competition and predation in the new environment. The aim of the bachelor 's thesis is to provide comprehensive information on the mechanisms of adaptation to a wide gradient of salinity in algae in general and to focus on freshwater-marine transitions in chrysophytes, that occurred repeatedly and relatively frequently in the course of evolution. Key words: chrysophytes, Chrysophyceae, salinity gradient, osmoregulation, marine- freshwater transition
|
|
|
What are the effects of ombro-minerotrophic transition in Central European peatlands on structure and dynamics of microalgal communities?
Hanousková, Andrea ; Neustupa, Jiří (advisor) ; Pusztai, Martin (referee)
Peatlands, as primary boreal habitats, are very rare and valuable azonal ecosystems in the Central European landscape. Their value is due, among others, to the enormous abundance of microalgae communities, of which probably the most prominent group consists of desmidiales, both in the richness of species and in their proportional representation. An important factor that affects peatland biota is the ombro-minerotrophy gradient derived from the hydrological regime. According to this concept, peat bogs are divided into two basic types - ombrotrophic peat bogs, which are saturated only by rainwater and minerotrophic fens, which are enriched by groundwater or surface water. The desmids, characterized by high sensitivity to environmental factors and species richness, are a very useful model group for ecological studies. In my work I deal with the effect of the ombro-minerotrophic gradient on the structure, diversity and dynamics of desmid communities on Sudeten peat bogs. The results show that ombro-minerotrophy significantly affects the structure of communities and is more determinant for the occurrence of individual species than their abundance. Significant effect was also found in species diversity. Minerotrophic peat bogs have apparently higher species diversity, which is mainly determined by the...
|
|
|
Distribution and diversity of freshwater rhodophytes
Žížalová, Lucie ; Neustupa, Jiří (advisor) ; Pusztai, Martin (referee)
This bachelor thesis is focused on systematics and distribution of freshwater red algae. There is a reference to the relationship between taxa and taxonomic groups and, possibly, their current and past classification. The thesis is based on the findings of published scientific papers. On the basis of this information, I have compiled an approximate current system of freshwater red algae with information about their distribution.
|
|
|
Adaptive functions of algal resting stages with emphasis on the chrysophyte stomatocysts
Mušálková, Petra ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
Formation of resting stages is a very common feature occurring in most algae classes. Primarily this stage is considered as a resistant form that helps the organism to survive adverse conditions and rapidly changing environment. However, it may also serve to spread as a seed bank to recolonize habitat or can be a source of genetic variation if it follows sexual reproduction. The importance of this dormant benthic stage grows with algae whose population growth is seasonal and the formation of cysts or spores is crucial for them, for instance dinoflagellates and golden algae. Resting stages of Chrysophyceae are called stomatocysts they are produced endogenously and are composed of polymerized silica. Stomatocysts have species-specific morphology. For most described species of Chrysophyceae morphology of the stomatocyst is unknown. Determining the species is difficult especially because of rapid alternation of chrysophyte dominant species in natural waterbodies. So far, it has not been elucidated what factors cause encystation and excystation. Several laboratory experiments has been conducted on this subject. The process of encystation and excystation is assumed to be induced by combination of external and internal factors. Stomatocysts may developed after sexual reproduction or from vegetative cells....
|
|
|
Phaeocystis - a key organism in dimethylsulfoniopropionate production; ecological and physiological functions of DMSP
Füllsacková, Alena ; Němcová, Yvonne (advisor) ; Pusztai, Martin (referee)
Dimethylsulfoniopropionate (DMSP) is an organic sulfur compound with an important ecological and physiological functions. DMSP is a major precursor for dimethylsulfid (DMS). DMSP is produced by variety of halophytic plants and phytoplankton for the purposes of osmotic regulation, antioxidation and protection from predators. It is especially widespread among the marine phytoplankton and it is ubiquitous in the euphotic zone. DMS and DMSP are also involved in flux of carbon and sulfur. Marine emissions of DMS have a particularly important role as precursors of atmospheric sulfur-containing aerosols that influence the Earth's climate system through direct backscatter of solar radiation and through cloud formation. DMSP is produced mainly by phytoplankton, because this group of organism is very large, I'll focus on Phaeocystis. Phaeocystis is a genus of marine phytoplankton with a worldwide distribution. It has a polymorphic life cycle alternating free-living cells and colonies but develops massive blooms under the colony form. Among the 10 species, only 3 (P. pouchetii, P. antarctica, P. globosa) have been reported as blooming species. DMSP is produced intracellulary and it is released as DMS. DMS concentration is high during the growth of the cells, predation or senescence. The production of DMSP is...
|
|
|
The role of microhabitats in spatio-temporal differentiation of phytoplankton flagellates
Pusztai, Martin ; Němcová, Yvonne (advisor) ; Bílý, Michal (referee)
This thesis deals with factors structuring phytoplankton flagellates. The aim of the thesis was to investigate the role of microhabitats in spatio-temporal differentiation of lentic communities of these flagellates, which has not been rigorously examined to date. The study was conducted during 2010-2013 in the shallow littoral sites of Horní rybník, Rybníčky u Podbořánek Nature Reserve. Phytoplankton flagellates showed cyclic seasonal dynamics, which was reflected by significantly different community structure and species richness during the season. In contrast, silica-scaled chrysophytes showed a non- cyclic seasonal dynamics. The impact of the season was strongly correlated with the impact of fluctuating environmental factors - pH, conductivity and temperature. Gradient of interrelated environmental factors between the northern and southern shore together with microhabitat - substrate type played the major role and accounted for 64.4 - 75.8 % variability in the data. Microhabitat type (plankton, metaphyton, epipelon) significantly affected species richness and community structure also in the course of the season. A large number of species was assessed to prefer a certain type of microhabitat. These preferences were observed at both species and generic levels, and even at the level of the main taxonomic...
|
|
|
The role of microhabitats in spatio-temporal differentiation of freshwater algal assemblages
Pusztai, Martin ; Němcová, Yvonne (advisor) ; Kulichová, Jana (referee)
This thesis deals with microhabitats in relation to the spatio-temporal differentiation of freshwater algal assemblages. Algae are defined ecologically, althought they represent a diverse polyphyletic conglomerate. Based on the available literature, type of substrate appears as a suitable representative of most freshwater microhabitats when comparing results from different studies. Influence of microhabitat may occur not only on a small spatial scale, but also on a regional scale. The importance of scale and traceability of different factors are further discussed as well as the appropriate definition of the microhabitat. Microhabitats diversity is often reflected in the spatial heterogeneity of algal assemblages. Based on the common trends in the algal life strategies, erosional and depositional substrates can be distinguished. Living substrates, especially macrophyte surfaces represent a special category of microhabitats. Algae can enter complex interactions with these living substrates.Temporal dynamics is relatively less explored in comparison with the spatial heterogeneity.
|
guest ::
