Nutrient limitation of benthic algae in Lake Baikal, Russia

Lake Baikal, one of the world’s largest and most biologically diverse lakes, has recently begun to experience uncharacteristic nuisance blooms of filamentous benthic algae. To contribute to understanding the causes of these blooms, we deployed nutrient-diffusing substrata (NDS) at 10 sites varying in shoreline land use in the southwestern portion of the lake. Our objectives were to assess the nature of nutrient limitation of benthic algae in Lake Baikal, the relationship between land use and limitation status, and the effect of enrichment on algal community composition. Algal biomass measured as chlorophyll a (Chl a) responded strongly to nutrient enrichment and showed serial limitation by N and P at all sites. Chl a levels were ~2 and 4 higher on N- and N1P-amended NDS, respectively, than on unenriched controls. Periphyton biomass varied significantly among sites, but differences in periphyton biomass and nutrient limitation status were not related to shoreline land use. The taxonomic composition of periphyton varied significantly among landuse categories, nutrient treatments, and sites. The filamentous green alga Stigeoclonium tenue, which has been associated with recently observed nuisance blooms in Lake Baikal, tended to be most abundant on N- and N1P-amended NDS. The results of our study demonstrate strong nutrient limitation of the periphyton in Lake Baikal and highlight the potential value of improved nutrient controls for addressing benthic algal blooms in the lake.