Until roughly a decade ago, most scientists assumed that phytoplankton remained in a sort of stasis throughout the winter and spring until sea ice break-up. Now there is a growing body of evidence that suggests under-ice blooms (UIBs) of phytoplankton can occur in low-light environments below sea ice.

“Up to about a decade ago, most Arctic phytoplankton research focused on open water and ice-edge conditions as there was a long-running assumption that not enough light reached under the sea ice cover to allow for a bloom to occur,” explained CJ Mundy, co-author of the study and Associate Professor at the University of Manitoba’s Centre for Earth Observation Science (CEOS).

“However, this assumption was flawed in that under-ice phytoplankton blooms can and do occur during the melt period (and sometimes before melt if the ice and snow cover are thin enough.”