Zone of the temperature optimum of cyanobacteria in the Kuibyshev reservoir

Based on the results of hydrometeorological observations in the period 2016-2021, the parameters of the optimum temperature zone (TTO) for the process of mass development of cyanobacteria in the Kuibyshev reservoir were determined. Such parameters of the optimum zone as duration, intensity, upper and lower boundaries depend on the hydrometeorological conditions of a particular year. For the period 2016-2021, the average duration of the OST was 44 days, the longest - 72 days and was observed in 2021, and the shortest - 11 days and was observed in 2019. The highest intensity of OST was observed in 2021, when 10 days were characterized by low intensity, 15 days by moderate intensity, 23 days by strong intensity, 24 days by very strong intensity and 7 days by extreme intensity. The lowest intensity was observed in 2019, when 10 days were characterized by low intensity and 1 day by high intensity. The upper border of the WTO in 2021 was observed on June 21, and the lower border on September 1. In 2019, the upper limit was observed on June 23, and the lower limit on July 26. For the process of mass development of cyanobacteria, the most favorable year is 2021, and the unfavorable year is 2019. It was found that with the increase in air and water temperature, the duration and degree of intensity of the temperature optimum zone increased. Consequently, with a further increase in air temperature due to global warming, the duration and intensity of the optimum temperature zone will only increase, which will activate the process of mass development of cyanobacteria, which will negatively affect the ecological state and water quality of the Kuibyshev reservoir.