Sea ice-dependent production of phytoplankton in the Canada basin in 2009

Abstract

From mid-September to mid-October of 2009 primary production of phytoplankton in the Canada Basin was measured, using both 13C-15N-dual tracer techniques. In addition, we identified the effects of light and nutrient enrichments on the primary production of phytoplankton residing the chlorophyll a maximum layer in connection with sea ice condition. The carbon and nitrogen production integrated over the euphotic zone ranged from 0.147 to 1.259 mg C m-2 h-1 and from 0.231 mg N m-2 h-1 to 0.726 mg N m-2 h-1 with a mean of 0.599 mg C m-2 h-1 (SD=±0.30 mg C m-2 h-1), 0.486 mg N m-2 h-1 (SD=±0.198 mg N m-2 h-1), respectively. The effect of light enrichment to the increase of the production was more effective below 50 % sea ice regions than over 50 % sea ice regions, while enriched nutrient could not affect to the increase of the production. This was because the phytoplankton under the relatively higher sea ice condition was experienced lower irradiance and this eventually might lead that these phytoplankton was more shade-adapted and thus induced slower response under the enriched light condition. Based on our result, we speculate that enriched light condition can rapidly elicit the primary production increase under the condition such as right after ice break up. The increase of light penetration due to the accelerated sea ice melt will provide a chance to the phytoplankton residing chlorophyll a maximum layer to contributing considerable portion in the production of Arctic Ocean.