ULTRAPLANKTON BIOMASS, PRODUCTIVITY AND EFFICIENCY IN LAC MATAMEC, A PRECAMBRIAN SHIELD LAKE.

In extremely oligotrophic Lac Matamec (Quebec, Canada) the ultraplankton (<15 μm) represented 47% of total phytoplankton biomass but accounted for 71% of the primary production and was 2.5 times more photosynthetically efficient than larger phytoplankton. Cell surface area was a good predictor of efficiency, while cell numbers and biomass were not. High surface:volume ratios may explain the high efficiency of the ultraplankton. [ABSTRACT FROM AUTHOR]