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Influence of fish pond management, land use in catchment and climate change on species composition of blue-green algae blooms
Kroupová, Kristýna ; Stuchlík, Evžen (advisor) ; Pivokonský, Martin (referee)
The aim of the thesis was to explain expansion of cyanobacterial blooms and the change of their species composition in surface standing waters during the last 2-3 decades as a result of fishery management, land use in catchments, and climate change. Cyanobacteria possess a range of unique and highly-adaptable eco-physiological traits, which enable them a mass occurrence and a dominance over the other phytoplankton groups under recent anthropogenic changes (nutrient loading and rising temperatures). Moreover, many species of cyanobacteria produce cyanotoxins, which increase their resistence against zooplankton grazing and cause severe deterioration of the water quality. In consequence of changes in fishery management (a decrease in the use of superphosphate as a fertilizer during the year 1970), the fish stock density increased and the clear water phase disappeared. This is responsible for a change in species composition of cyanobacterial water blooms. Summer blooms of Aphanizomenon flos-aquae were replaced with A. flos-aquae var. klebahnii. The current composition of water blooms in ponds differs considerably from the typical composition in the 1990s. For example, recent expansion of Woronichiniana naegeliana is caused by the higher stock densities and the shift from a two-year cycle of fishery management...
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Anabaena - Phenotypic and genotypic diversity of planktonic strains in fishponds and reservoirs of the Czech Republic
ZAPOMĚLOVÁ, Eliška
Morphological diversity of 61 Anabaena populations of 13 morphospecies was described under the field conditions of Czech fishponds and reservoirs. Polyphasic approach was then applied in classification of 45 clonal strains isolated from those populations. Detailed morphological analyses were performed and partial 16S rRNA gene sequences were obtained for 33 of the strains, and secondary metabolite production was evaluated in 20 strains. Plasticity of morphological characteristics under varied conditions of light, temperature, nitrogen and phosphorus was studied in selected strains, as well as their temperature and light growth requirements. The results were then discussed with respect to the delimitation of single Anabaena morphospecies. A new genus Sphaerospermum was defined for the morphospecies Anabaena kisseleviana, A. reniformis and Aphanizomenon aphanizomenoides, whose phenotypic and genotypic features differed considerably from all other Anabaena morphospecies. Unique information was provided on the occurrence and distribution of A. reniformis and Aph. aphanizomenoides in the Czech Republic.
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