Dynamics of abundance and biomass of Gonyostomum semen (Ehr.) Diesing in Valaam lakes

Abstract

The paper presents long-term material on the succession of species Gonyostomum semen (Ehr.) Diesing collected on the lakes of the Valaam archipelago. The work was carried out on 10 small 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. 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 (27–296° 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 in biomass rafidophyte algae dominated. G. semen biomass varied from 1,1 to 82,3 mg/dm3. 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.