|
|
Food webs of glacier-fed streams.
Komárková, Julie ; Kopalová, Kateřina (advisor) ; Fuksa, Josef (referee)
This work focuses on glacier-fed stream ecosystems, with the centre of attention being on the community composition and characterization of their food web structure. Glacier-fed streams are harsh environments in terms of their physicochemical characteristics. These streams exhibit low temperatures and specific flow regimes, with the peak of meltwater generation, and thus discharge, in the summer. In turn, streamwater nutrient concentrations, light availability, and turbidity all vary seasonally according to the flow regime. Compositionally, glacier-fed stream habitats host chemolithotrophic bacteria along with photoautotrophic producers, such as diatoms, Chrysophyceae, and Cyanobacteria, which together serve at the bottom of food webs as primary producers. These streams also host some fungal taxa, that together with heterotrophic bacteria, represent the primary decomposers. Macroinvertebrates, including the water larvae of species Diamesa and Pseudodiamesa, or from the Ephemeroptera or Plecoptera groups, are important secondary producers with high feeding plasticity; that is, they are mainly grazing biofilm or collecting/filtering organic matter, with the possibility of predation. Other than that, in glacier-fed streams, there is usually no presence of higher trophic levels with large- bodied...
|
|
|
Diatoms as bioindicators for tracking freshwater salinization.
Severa, František ; Kopalová, Kateřina (advisor) ; Dobiáš, Jakub (referee)
The focus of this thesis is on the relationship of diatom (Bacilariophyta) communities to conductivity, and the utilization of this relationship for the monitoring of freshwater salinization. Salinization of freshwaters as a consequence of anthropogenic influences is emerging as a threat to many freshwater habitats due to increasing anthropogenic sources of salts (like use of de-icing salts on roads), wastewaters, and fertilizers. The problem is intensifying because salts are further concentrated through increased evaporation as a consequence to climatic changes. Salinization of ecosystems has a direct impact on the physiological processes of present organisms, and because the ability to adapt to this stress differs between organisms, results in the reorganization of communities. In this way, salinization can indirectly threaten ecosystem services that benefit mankind. Furthermore, salinization is a direct threat in terms of its influence on drinking water and crop irrigation. These forces also act on diatoms, which have long been used as bioindicators, and exhibit strong community links with conductivity. Like for other organisms, this tight relationship is caused by differences in adaptation mechanisms between species, which includes osmolytes, extracellular polymeric substances and adaptation of...
|
|
|
Role of microbes in the decomposition in headwater streams.
Kociánová, Petra ; Kopalová, Kateřina (advisor) ; Tátosová, Jolana (referee)
The decomposition of organic matter in headwater streams is a key process in stream ecology and an important component of the global carbon cycle. Decomposition rates depend on both abiotic and biotic factors, the former including temperature, discharge, and nutrient chemistry, and the latter including stream community structure and activity, trophic interactions, biodiversity, and productivity. Of the stream community, microbial decomposers play a particularly important role in decomposition by chemically degrading compounds and transferring nutrients and energy to higher trophic levels. These processes are prone to change due to current and future global warming which will affect both decomposer communities and associated decomposition rates. This thesis provides a short overview of the main factors that control stream decomposition rates, including biological factors like microbial activity, abiotic factors such as water temperature and nutrient availability, and how these factors may be altered in the future under a warmer climate. Specifically, I predict that climate change will increase microbial activity and decomposition in headwater streams due to increased water temperatures, changes in surrounding vegetation, and shifts in the hydrological regime due to global warming. .
|
|
| |
|
|
Biogeography and habitat preferences for genus Luticola
Hanišová, Lucie ; Kopalová, Kateřina (advisor) ; Kulichová, Jana (referee)
The genus Luticola is one of the most species rich group belonging to the diatom class (Bacillariophyceace) containing 204 described species. The aim of this work is to summarize the available literature on the genus Luticola concerning its biogeography, habitat preferences of polar and temperate species, and their ecological treshold for important factors relating and forming their presence - pH and conductivity. Records suggest that the Luticola genus is presence worldwide, with higher species diversity in Europe, South America and the Antarctic region, the latter of which harbors a substantial amount of endemic species. In terms of habitat preference, records suggest that temperate species occur mostly in aquatic habitats, while polar species occupy terrestrial environments. Polar species also differ from temperate species by occupying narrower margin of pH values. However, both groups prefer low conductivity, and most species of the genus Luticola are located in environments with values up to 100 μS/cm. Key words: biogeography, conductivity, Luticola, pH.
|
|
|
Subfossil Cladocera as a powerful tool for paleoecological reconstruction
Bubenková, Anna ; Tátosová, Jolana (advisor) ; Kopalová, Kateřina (referee)
This bachelor thesis is a literature review documenting the usage of subfossil Cladocera in paleoecological reconstruction. Its aim is to argue for subfossil Cladocera as an effective means of studying historical evolution of lakes and identifying significant processes which formed them over time. Furthemore, this literature review critically evaluates some of the most common approaches to reconstructing changes in climate, water levels, acidification, and eutrophication, and numerous issues they often encouter. The correct interpretation is vital because all the factors in the aquatic environment are connected. Despite some debate, subfossil Cladocera are an important aspect of paleoecological reconstructions with much possible utilization in future research. Key words: subfossil Cladocera, paleoecology, reconstruction
|
|
|
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...
|
|
| |
|
|
Ecology and Taxonomy of limno-terrestrial diatoms from East Antarctica.
Bishop, Jordan ; Kopalová, Kateřina (advisor) ; Hutňan Chattová, Barbora (referee) ; Jüttner, Ingrid (referee)
Diatoms are single-celled photosynthetic eukaryotes that substantially contribute to global primary productivity. They are also among the most diverse groups of organisms in Antarctica. Biogeographically, Antarctica is divided into three distinct regions including the Sub-Antarctic, Maritime Antarctic, and Continental Antarctic. Recent taxonomic revisions of diatoms within the Sub-Antarctic and Maritime Antarctic Regions have uncovered a number of endemic taxa initially misidentified as cosmopolitan due to species "force-fitting". Within Continental Antarctica, this taxonomic uncertainty has led to confusion about the environmental drivers of limno-terrestrial diatom communities, although this knowledge is important given the use of diatoms as regional bioindicators for environmental change. The purpose of this dissertation is to reevaluate the diatom flora of Continental Antarctica and determine variables that structure their communities within two historically and biologically important localities within East Antarctica; the Vestfold Hills and Windmill Islands. The erection of the genus Sabbea was performed to accommodate a long-misidentified species, Sabbea adminensis, that occurs within the Vestfold Hills and McMurdo Sound Region where it had been the source of taxonomic confusion since the...
|
|
| |
guest ::
RSS feed.