The metabolic balance between autotrophy and heterotrophy in the western Arctic Ocean

Abstract

The goal of this study was to explore how net community production (NCP) is influenced by the relationship between primary production and community respiration in the western Arctic Ocean. Plankton NCP and respiration were determined by measuring changes in oxygen in light and dark bottle incubations, respectively. Rates of NCP averaged over shelf, slope and basin waters were positive in summer 2002 (57±191 mmol O 2 m −2 d −1) and spring 2004 (85±86 mmol O 2 m −2 d −1) and negative in summer 2004 (−25±176 mmol O 2 m −2 d −1). Determinations of NCP obtained from bottle incubations were similar to rates inferred from in situ changes in dissolved inorganic carbon. An examination of the spatial variability of primary production and community respiration indicated that respiration is distributed more uniformly than primary production. A spatial offset between photosynthesis and respiration from the shelf to the Arctic basin was present in spring 2004, but was not seen at other times. NCP and the potential for export appear to be dependent on an uncoupling of primary production and community respiration. NCP continued into the summer after the stock of NO 3 − had been depleted. Our data suggest that the uniform distribution of respiration relative to primary production is an important factor influencing NCP and the potential for export in the western Arctic.