SPATIAL-DISTRIBUTION OF PHYTOPLANKTON IN LAKE-BAIKAL, SPRING 1991

1. Studies carried out in Lake Baikal in late spring (late May-early J une) 1991 showed marked differences in the species composition and abu ndance of phytoplankton in different regions of the lake. The south an d north basins were characterized by small forms of algae. The middle basin, Maloe More and the shallow waters of the Selenga had species wi th large cells including Aulacoseira islandica subsp. helvetica, Dinob ryon cylindricum and D. divergens. 2. Areas of high biomass were corre lated with shallow waters and river inputs. This was especially appare nt in the region of the Selenga delta. The vertical distribution of ph ytoplankton indicated the non-synchronous start of the spring homother my throughout the lake. Phytoplankton were concentrated in the upper 1 00 m layer with subsurface maxima resulting from the sinking of large algae. 3. The concentration of phytoplankton biomass in general at thi s time characterized the lake as moderately productive.