Incident of algae blooms of Lake Svyatozero (Karelia, Russia)

Abstract

The article presents results of the investigation of the littoral zone state in the northern part of Lake Svyatozero (Karelia) according to microbiological and phytoplankton indicators. We studied the causes of the appearance of a bloom spot in September 2019. The total abundance of bacteria was 6.4210⁶ cells/ml, the abundance of saprophytic bacteria growing at 22 was 20.310³ CFU/ml, saprophytic bacteria growing at 37 was 1.7410³ CFU/ml. The development of bacteria indicated that self-purification processes were completed. The total abundance of phytoplankton was 198712.510³ cells/l, and the total biomass was 14.945 mg/l. A total of 17 phytoplankton species were identified, 14 of which were ranked Cyanophyta (96.7% of the total abundance and 99.8% of the total biomass). Microcystis aeruginosa inhibiting the development of bacterioplankton was found in the water. Blooming of blue-green algae was apparently due to secondary pollution of the water body following low water level, wind intensity, waterborne soil movement, and warm weather. During the study period, water from the littoral zone in the northern part of Lake Svyatozero was estimated as highly polluted with the quality class 4 and was characterized as a stopgap measure from mesotrophic to the eutrophic water body.