Presence and identification of Legionella and Aeromonas spp. in the Great Masurian Lakes system in the context of eutrophication

Growing anthropopressure over the last several decades has resulted in rapid progressive eutrophication of the Great Masurian Lakes (GML) system located in northeastern Poland. In our studies, we investigated whether there is a relationship between the occurrence of pathogenic bacteria: Legionella spp. and Aeromonas spp., not explored so far in the waters of GML system, and the trophic status of the studied lakes. The GML system of glacial origin includes lakes connected by natural and artificial channels, and it extends from north to south for approximately 100 kilometers. Water samples were taken during the summer, subsequently spring and autumn seasons from 15 lakes in land-water ecotones. At all sampling sites, basic in situ measurements of physicochemical parameters were recorded. The amounts of chlorophyll a, nitrogen, phosphorus, dissolved organic carbon were also measured. The trophic state index (TSI) of the sampling sites was also estimated. The real-time PCR technique enabled the determination of the presence and abundance of Legionella spp. and Aeromonas spp. The results clearly showed that several environmental water quality parameters, associated with eutrophication, and among them: nitrogen, phosphorus, chlorophyll, ammonium concentration, conductivity, turbidity, water transparency, highly affected the presence and abundance of the detected pathogenic bacteria in the studied lakes. Special attention should be paid to the high impact of water eutrophication on the number of pathogenic microorganisms, which result both from human activities in lakes and climate change.