Regional productivity of phytoplankton in the Western Arctic Ocean during summer in 2010

Abstract

Phytoplankton production measurements were conducted in the northeast Chukchi Sea and western Canada Basin in the summer season, from 20 July to 10 August 2010, using a ¹³C？¹⁵N dual tracer technique. The daily carbon uptake rate in the northeast Chukchi Sea in 2010 was extremely low, with a mean of 29.8 mg C m^-2d^-1 (SD=17.6 mg C m^-2d^-1). Regional and temporal differences caused the low production rate compared to previous studies in the northeast Chukchi Sea. In the western Canada Basin, the mean daily carbon uptake rate from this study was 20.6 mg C m^-2 d^-1, which was influenced by the dominance of small phytoplankton resulting in a low carbon uptake rate in the region. The regionally high nitrate uptake rates compared to ammonium uptake rates in the western Canada Basin can be caused by warm-core eddies, which supply high levels of nitrate to the euphotic zone. Warm-core eddies in the Canada Basin substantially enhanced local phytoplankton production and the contribution of large phytoplankton. Therefore, the effects of physical forcing events (such as "an" eddy) on the primary production need to be examined further to better understand changes of primary production under ongoing environmental changes in the Arctic Ocean.