1. Barren icesheets

In the high Arctic, snow-covered sea ice absorbs much of the solar radiation necessary for photosynthesis. But by late summer, the ice has thinned enough to allow a seasonal bloom of tiny plants called phytoplankton. The largest natural upwelling of sea water in the ecozone is the North Water Polynya. It occurs in northern Baffin Bay near Nares Strait, encouraging an earlier and more prolific bloom of phytoplankton than elsewhere in the ecozone. Further south, inter-tidal zones support forests of kelp.