TY - JOUR

T1 - Autotrophic and heterotrophic activity in Arctic first-year sea ice

T2 - seasonal study from Malene Bight, SW Greenland

AU - Søgaard, Dorte Haubjerg

AU - Kristensen, Morten

AU - Rysgaard, Søren

AU - Glud, Ronnie Nøhr

AU - Hansen, Per Juel

AU - Hillingsøe, Karen Marie

N1 - KEY WORDS: Sea ice · Primary production · Bacterial carbon demand · Net autotrophic activity · Net heterotrophic activity · Attenuation coefficient

PY - 2010

Y1 - 2010

N2 - We present a study of autotrophic and heterotrophic activities of Arctic sea ice (Malene Bight, SW Greenland) as measured by 2 different approaches: (1) standard incubation techniques (H14CO3– and [3H]thymidine incubation) on sea ice cores brought to the laboratory and (2) cores incubated in situ in plastic bags with subsequent melting and measurements of changes in total O2 concentrations. The standard incubations showed that the annual succession followed a distinctive pattern, with a low, almost balancing heterotrophic and autotrophic activity during February and March. This period was followed by an algal bloom in late March and April, leading to a net autotrophic community. During February and March, the oxygen level in the bag incubations remained constant, validating the low balanced heterotrophic and autotrophic activity. As the autotrophic activity exceeded the heterotrophic activity in late March and April, it resulted in a significant net oxygen accumulation in the bag incubations. Integrated over the entire season, the sea ice of Malene Bight was net autotrophic with an annual net carbon fixation of 220 mg C m– 2, reflecting the net result of a sea ice-related gross primary production of 350 mg C m– 2and concurrent bacterial carbon demand of 130 mg C m– 2. Converting the O2 net exchange of the bag incubations into carbon turnover estimated an annual net carbon fixation of 1700 ± 760 mg C m– 2 (mean ± SD), which was higher than the annual net carbon fixation quantified in the standard incubations

AB - We present a study of autotrophic and heterotrophic activities of Arctic sea ice (Malene Bight, SW Greenland) as measured by 2 different approaches: (1) standard incubation techniques (H14CO3– and [3H]thymidine incubation) on sea ice cores brought to the laboratory and (2) cores incubated in situ in plastic bags with subsequent melting and measurements of changes in total O2 concentrations. The standard incubations showed that the annual succession followed a distinctive pattern, with a low, almost balancing heterotrophic and autotrophic activity during February and March. This period was followed by an algal bloom in late March and April, leading to a net autotrophic community. During February and March, the oxygen level in the bag incubations remained constant, validating the low balanced heterotrophic and autotrophic activity. As the autotrophic activity exceeded the heterotrophic activity in late March and April, it resulted in a significant net oxygen accumulation in the bag incubations. Integrated over the entire season, the sea ice of Malene Bight was net autotrophic with an annual net carbon fixation of 220 mg C m– 2, reflecting the net result of a sea ice-related gross primary production of 350 mg C m– 2and concurrent bacterial carbon demand of 130 mg C m– 2. Converting the O2 net exchange of the bag incubations into carbon turnover estimated an annual net carbon fixation of 1700 ± 760 mg C m– 2 (mean ± SD), which was higher than the annual net carbon fixation quantified in the standard incubations

U2 - 10.3354/meps08845

DO - 10.3354/meps08845

M3 - Journal article

VL - 419

SP - 31

EP - 45

JO - Marine Ecology - Progress Series

JF - Marine Ecology - Progress Series

SN - 0171-8630

ER -