Under-Ice Microalgae and Algae of the Interstitial Icy Water Functioning in Lake Baikal Littoral Zone

Abstract

The results of field studies of the species composition and productive parameters (biomass, photosynthesis rate, chlorophyll a content, and assimilation numbers) of microalgae in the plankton and the interstitial icy waters of Lake Baikal southern littoral area obtained in March 2018 are presented. A comprehensive study of the ice and phytoplankton algae showed that their productive activity was relatively low at most stations. Their higher values observed near river mouths with significant anthropogenic pollution were caused by both the additional nutrient input and development of small-sized algae, primarily of phytoflagellates, which indicate water pollution by organic matter inflowing to Lake Baikal with its tributaries. Using the principal component method, we failed to reveal reliable correlation between the primary producers and the microorganisms decomposing organic matter into mineral substances (the correlation coefficient was 0.49). The differences between the stations subject to anthropogenic impact and the reference ones indicate that access to easily mineralized organic matter promoted the massive development of phytoflagellates. Although large-cell diatoms common in the lake were absent, primary production at these sites reached 100 to 280 mg C m−2, which was comparable with the values obtained for abundant diatom blooms during the under-ice period. High functional potential of the algae at the areas subject to anthropogenic impact results in significant biomass accumulation, which leads eutrophication of the littoral zone and may lead to increased primary production of the pelagic zone.