Dissolved oxygen (DO) concentrations in the ocean
are dependent on a number of physical and biological
processes, including circulation, ventilation, air-sea exchange,
production and respiration. Climate-driven changes
in these processes should therefore be reflected in oceanic
DO observations [Deutsch et al., 2005]. In particular,
models driven by increasing greenhouse gases predict a
decline in midwater oceanic DO as a result of enhanced
stratification and reduced ventilation [Sarmiento et al.,
1998; Keeling and Garcia, 2002]. These changes will have
a significant impact on the biological pump locally, while
changes in large-scale circulation will act to spread and
modify the oxygen signal. Spreading of low-oxygen waters