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Sirvi Autor "Panksep, Kristel (advisor)" järgi

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    Occurrence and trophic interactions of the potentially toxic bloom-forming cyanobacterial genus Microcystis in shallow temperate lakes
    (Estonian University of Life Sciences, 2026) Gonzales Ferraz, Margarita Esmeralda; Agasild, Helen (advisor); Panksep, Kristel (advisor); Nõges, Tiina (advisor); Institute of Agriculture and Environmental Sciences; Dimante-Deimantovica, Inta (opponent)
    ABSTRACT. The increasing frequency and intensity of toxic cyanobacterial blooms pose a serious threat to aquatic ecosystems and the services they provide. Among the dominant bloom-forming genera, Microcystis is commonly observed in highly eutrophic waterbodies and represents a major concern due to its toxin production and potential contamination of food webs. As toxic and non-toxic strains of Microcystis often coexist within the same assemblage, qPCR targeting the genus-specific microcystin synthetase gene mcyE is a valuable tool for determining toxigenic strains in the environment and in the consumer diet. The research focused on bloom-forming and potentially toxic cyanobacteria, Microcystis, by characterizing the dynamics of its toxic strains and environmental drivers, as well as its trophic interactions in the aquatic food webs of lakes Võrtsjärv and Peipsi. The research demonstrated that in temperate, ice-covered lakes, Microcystis's ability to produce toxigenic strains may persist year-round. Application of genus-specific qPCR detection in zooplankton gut contents revealed that in natural waterbodies, various cladoceran and copepod species can consume toxigenic Microcystis strains, potentially posing a risk to higher trophic levels. It also showed that even in lakes with very low levels of toxigenic Microcystis, toxic cell trophic pathways can still occur, as evidenced in Lake Võrtsjärv. The research further emphasizes that, to assess the toxicity risk of Microcystis to the food web, the knowledge of grazer assemblages and their dynamics is essential. Further research on Estonia’s large lakes, Võrtsjärv and Peipsi, should focus on directly measuring cyanotoxin concentrations to better assess the potential risks of microcystin contamination in these ecosystems.