In-situ Measured Carbon and Nitrogen Uptake Rates of Melt Pond Algae in the Western Arctic Ocean, 2014

Abstract

Although the areal coverage of melt pond in the Arctic Ocean has recently increased, very few biological researches have been conducted. The objectives in this study were to ascertain the uptake rates of carbon and nitrogen in various melt ponds and to understand the major controlling factors for the rates. We obtained 22 melt pond samples at ice camp 1 (146.17°W, 77.38°N) and 11 melt pond samples at ice camp 2 (169.79°W, 76.52°N). The major nutrient concentrations varied largely among melt ponds at the ice camps 1 and 2. The chl-a concentrations averaged from the melt ponds at camps 1 and 2 were 0.02–0.56 mg chl-a m-³ (0.12 ± 0.12 mg chl-a m^-3) and 0.08–0.30 mg chl-a m^-3 (0.16 ± 0.08 mg chl-a m^-3), respectively. The hourly carbon uptake rates at camps 1 and 2 were 0.001–0.080 mg C m^-3 h^-1 (0.025 ± 0.024 mg C m^-3 h^-1) and 0.022–0.210 mg C m^-3 h^-1 (0.077 ± 0.006 mg C m^-3 h^-1), respectively. In comparison, the nitrogen uptake rates at camps 1 and 2 were 0.001–0.030 mg N m^-3 h^-1 (0.011 ± 0.010 mg N m^-3 h^-1) and 0.002–0.022 mg N m^-3 h^-1 (0.010 ± 0.006 mg N m^-3 h^-1), respectively. The values obtained in this study are significantly lower than those reported previously. A large portion of algal biomass trapped in the new forming surface ice in melt ponds appears to be one of the main potential reasons for the lower chl-a concentration and subsequently lower carbon and nitrogen uptake rates revealed in this study. A long-term monitoring program on melt ponds is needed to understand the response of the Arctic marine ecosystem to ongoing environmental changes.