Phytoplankton succession of the Valaam archipelago lakes

Abstract

The paper presents long-term material on the succession of phytoplankton collected on the lakes of the Valaam archipelago. The work was carried out on 11 lakes about Valaam archipelago, maintaining a natural mode of functioning. The lakes differed in the shape of the basin, depth, and features of the hydrochemical regime. Phytoplankton samples were taken once a month from May to October 1998–2019. In parallel with sampling, studies of the main limnological parameters were carried out. For lakes, a wide range of limnological parameters was revealed, such as transparency (0,3–4,6 m), active reaction of the environment (4,0–8,6), water color (27–296о according to Pt-Co scale), the content of total organic matter (10,8–63,8 mgO/dm3) and mineral phosphorus (0,001–0,646 mg/dm3). The phytoplankton structure varied significantly from lake to lake. In terms of abundance in most small lakes, cyanobacteria (in abundance) and rafidophyte (in biomass) algae dominated. Abundance of phytoplankton and biomass varied from 0.1 to 676.6 million cells/dm3 and from 0.1 to 105.2 mg/dm3, accordingly. In acidic polyhumous lakes, a simplification of the phytoplankton structure was noted. Representatives of the department of green algae (chlorococcal, volvox, ulotrix) dominated in these lakes throughout the season. In the seasonal dynamics of phytoplankton, one or two peaks were noted, which occurred in different years in different months, most often in June or September. It was shown that the variation in the structural parameters of the phytoplankton of lakes was determined by the specific catchment area, the depth of the reservoir, water transparency, color, electrical conductivity and nutrient content. To a large extent, the level of phytoplankton vegetation was also determined by the active reaction of the environment.