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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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