Chlorophyll and photosynthetic efficiency of size-fractionated sea-ice microalgae (Hudson Bay, Canadian Arctic)

Abstract

Microalgal samples collected at the ice-water interface (Hudson Bay, Canadian Arctic) were size fraction-ated in order to determine if small algae, corresponding to the slze of picoplankton in open waters, were present m the sea-Ice environment. The <5 pm fraction was found to account for up to 4 % of total chlorophyll a and 20 % of total chlorophyll c. Photosynthetically active algae were present in the < l km fraction. Their photosynthetic efficiency was lower than that of the large ice diatoms, which indicated better adaptation of these larger cells to low under-ice light intensities. This is contrary to what has generally been observed for picoplank-ton in open waters. The ecological significance of ice pico-algae remains to be assessed.