Phytoplankton production from melting ponds on Arctic sea ice

Abstract

Recently, the areal extent of melt ponds within sea ice has rapidly increased during the Arctic Ocean summer. However, the biological impacts of melt ponds on the Arctic marine ecosystem have rarely been studied. Carbon and nitrogen uptake rates of phytoplankton were measured at 26 different melt ponds in 2005 and 2008, using a ¹³C-¹⁵N dual stable isotope tracer technique. Generally, the open ponds had relatively higher nutrients than closed ponds, but the nutrient concentrations in the open ponds were within a range similar to those in surrounding surface seawaters. Chlorophyll <em>a</em> (Chl <em>a</em>) concentrations in melt ponds ranged from 0.1 to 2.9 mg Chl<em> a </em>m^-3 with a mean of 0.6 mg Chl <em>a </em>m^-3 (SD = 0.8 mg Chl <em>a</em> m^-3) in the Canada Basin in 2005, whereas the range of the Chl <em>a </em>concentrations was from 0.1 to 0.3 mg Chl <em>a</em> m^-3 with a mean of 0.2 mg Chl <em>a</em> m^-3 (SD = 0.1 mg Chl <em>a</em> m^-3) in the central Arctic Ocean in 2008. The average annual carbon production in sea ice melt ponds was 0.67 g C m^-3 (SD = 1.03 g C m^-3) in the Arctic Ocean. Based on this study, recent annual carbon production of all melt ponds was roughly estimated to be approximately 2.6 Tg C, which is less than 1% of the total production in the Arctic Ocean.