Primary and new production in the deep Canada Basin during summer 2002

The NOAA Ocean Exploration program provided the opportunity to measure the carbon and nitrogen productivity across the Canada Basin. This research examined the major environmental factors limiting the levels of primary production and possible future climate change on the ecosystems. The vertical distributions of the carbon and nitrogen uptakes of phytoplankton had similar patterns as their respective biomass concentrations which were low at the surface and highest in the chlorophyll-maximum layer. The annual carbon and new production rates of phytoplankton in the Canada Basin were about 5 and 1 g C m(-2), respectively. Nutrients were determined to be a main limiting factor at the surface, whereas light may be a major factor limiting phytoplankton productivity in the chlorophyll-maximum layer for open waters. The bottom surface of the ice has a low specific uptake and productivity of phytoplankton, indicating that photosynthetic activity might be controlled by both light and nutrients.