Fig. 1. The Malaspina 2010 Circumnavigation Expedition.

The stations along the cruise track (A). Dissolved oxygen concentration (B) and downwelling irradiance (C) in the visible spectrum (400 to 700 nm) in μmol quanta m⁻² s⁻¹ (logarithmic scale). Daytime DSL weighted median depths (blue line) with 25 and 75% quartiles (black lines) are indicated in (B) and (C). Downwelling irradiance was measured down to depths of 180 to 280 m and calculated according to a proxy model (see Materials and Methods) of light attenuation beyond. Distance is the distance traveled along the cruise track from the first station.