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Seasonal dynamics of mats composed by green alga Zygnema (Zygnematophyceae)
Trumhová, Kateřina
The mats formed by Zygnema spp. are well known and frequently found in streams, puddles, seepages, and ponds. Owing to the low and inconsistent water quantity of these biotopes, algae are periodically subjected to stresses like desiccation, freezing, or strong solar radiation. Recent studies have revealed that Zygnema survives various stresses in pre-akinetes, modified resistant vegetative cells. However, earlier experiments mostly aimed at osmotic stress and desiccation. Moreover, the mats formed by these algae have seasonal dynamics that have been observed several times, not only in temperate conditions but also in the Arctic. Field observations revealed that most of the biomass is periodically lost, and new mats are formed every year. Simultaneously, we know little about the genetic composition of the mats and how it changes over time; previous work has focused mainly on the mats as an entirety. Therefore, this work mainly aimed to subject the mats formed by the algae Zygnema spp. to long-term observation and subsequent experiments. We selected a region in the Austrian Alps, which we visited several times a year, and sampled two sites with different water regimes. Further research in collaboration with colleagues occurred in the Arctic. Zygnema spp. strains were subsequently isolated from the...
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Seasonal dynamics of mats composed by green alga Zygnema (Zygnematophyceae)
Trumhová, Kateřina ; Pichrtová, Martina (advisor) ; Remias, Daniel (referee) ; Žárský, Jakub (referee)
The mats formed by Zygnema spp. are well known and frequently found in streams, puddles, seepages, and ponds. Owing to the low and inconsistent water quantity of these biotopes, algae are periodically subjected to stresses like desiccation, freezing, or strong solar radiation. Recent studies have revealed that Zygnema survives various stresses in pre-akinetes, modified resistant vegetative cells. However, earlier experiments mostly aimed at osmotic stress and desiccation. Moreover, the mats formed by these algae have seasonal dynamics that have been observed several times, not only in temperate conditions but also in the Arctic. Field observations revealed that most of the biomass is periodically lost, and new mats are formed every year. Simultaneously, we know little about the genetic composition of the mats and how it changes over time; previous work has focused mainly on the mats as an entirety. Therefore, this work mainly aimed to subject the mats formed by the algae Zygnema spp. to long-term observation and subsequent experiments. We selected a region in the Austrian Alps, which we visited several times a year, and sampled two sites with different water regimes. Further research in collaboration with colleagues occurred in the Arctic. Zygnema spp. strains were subsequently isolated from the...
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The diversity of filamentous freshwater algae and factors affecting the dynamics of their communities
Hadravová, Anna-Marie ; Šťastný, Jan (advisor) ; Woodard, Kateřina (referee)
This bachelors thesis is summing up the knowleadge from published papers which are dealing with the ecology of filamentous algae communities. It is focused on how the seasonal dynamics and biotic and abiotic factors do affect the communities of filamentous algae. The first part of the thesis contains a taxonomical overview of genera of the concern. In the second part there are different types of water habitats divided by their morphology and other characteristics (depth, temperature etc.). I am dealing with the factors affecting the composition of filamentous algae communities in stagnant waters of the temperate zone. No comprehensive works focusing on this field have been published so far. My thesis presents a synthesis of knowledge from avaliable sources. The species concepts of many filamentous algae are quite confusing, that is why their species determination is so difficult. That is the reason why there are not many journal articles dealing with such ecological issues. Key words: filamentous algae, ecology, freshwater habitats, diversity
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