Secular trends in Arctic Ocean net primary production

A satellite-based study was conducted to document daily changes in net primary production (NPP) by phytoplankton in the Arctic Ocean from 1998 to 2009 using fields of sea ice extent, sea surface temperature, and chlorophyll a concentrations. Total annual NPP over the Arctic Ocean exhibited a statistically significant 20% increase between 1998 and 2009 (range = 441-585 Tg C yr -1 ), due mainly to secular increases in both the extent of open water (+27%) and the duration of the open water season (+45 days). Increases in NPP over the 12 year study period were largest in the eastern Arctic Ocean, most notably in the Kara (+70%) and Siberian (+135%) sectors. NPP per unit area for the Arctic Ocean averaged 101 g C m -2 yr -1 with no significant change over the study period. In the western sectors, NPP ranged from 71.3 11.0 g C m -2 yr -1 in the Beaufort to 96.9 7.4 g C m -2 yr -1 in the Chukchi, while in the more productive eastern Arctic, annual NPP between 1998 and 2009 ranged from 101 15.8 in the Siberian sector to 121 20.2 in the Laptev. Results of a statistical analysis suggest that between 1979 and 1998 (prior to the launch of SeaWiFS and MODIS), total Arctic NPP likely averaged 438 21.5 Tg C yr -1 . Moreover, when summer minimum ice cover drops to zero sometime during the first half of this century, annual NPP in the Arctic Ocean could reach 730 Tg C yr -1 . Nutrient fluxes into Arctic surface waters need to be better understood to determine if these projected increases are sustainable.