Impacts of water depth, sediment pigment concentration, and benthic macrofaunal biomass on sediment oxygen demand in the western Arctic Ocean

We investigated the impacts of water depth, sediment pigment concentration, and benthic macrofaunal biomass on sediment oxygen demand (SOD) during three cruises to the western Arctic Ocean. SOD values were similar to those of most studies from the Arctic and ranged from a high of 20.68 mmol O(2 center dot)m(-2 center dot)day(-1) at a shallow shelf station to a low of 0.29 mmol O(2 center dot)m(-2 center dot)day(-1) at the deepest basin station (3648 m). SOD was significantly greater at shallow sites (< 500 m; mean = 7.39 mmol O(2 center dot)m(-2 center dot)day(-1); standard deviation (SD) = +/- 5.38) than at deep sites (> 500 m; mean = 1.39 mmol O(2 center dot)m(-2)center dot ay(-1); SD = +/- 0.96). As hypothesized, SOD was negatively correlated with water depth and positively correlated with both surface-sediment pigment concentration and macrofaunal biomass, with macrofaunal biomass explaining approximately 74% of the variability in SOD. We propose that higher macrofauna-normalized respiration rates (i.e., SOD divided by macrofaunal biomass) in deep water indicate that microbial-meiofaunal respiration predominates in deep versus shallow water. Finally, deeper stations associated with Barrow Canyon had SODs, benthic macrofaunal biomass, and surface-sediment pigment concentrations that were similar to those of shallower shelf locations, suggesting down-canyon transport of organic material.