Seasonal dynamics of primary production in the pelagic zone of southern Lake Baikal

We measured primary production by phytoplankton in the south basin of Lake Baikal, Russia, by in situ ^sup 13^C-bicarbonate incubations within the period March-October in two consecutive years (1999 and 2000). Primary production was highest in the subsurface layer, possibly due to near-surface photoinhibition of photosynthesis, even under 0.8m of ice cover in March. Areal primary production varied from 79mgCm^sup -2^day^sup -1^ (March) to 424mgCm^sup -2^day^sup -1^ (August), and annual primary production was roughly estimated as 75gCm^sup -2^year^sup -1^, both of which are within the lower range of previous estimates. Size fractionation measurements revealed that phytoplankton in the