Mapping Areas of the Southern Ocean Where Productivity Likely Depends on Dust‐Delivered Iron

Abstract

AbstractThe existence of low‐productivity areas in the Southern Ocean has been related to limited supply of bioavailable iron from terrestrial sources of dust. Dust‐delivered iron can be crucial to ocean productivity, though alternative mechanisms have also been identified. To explore the geographic distribution of areas limited in the delivery of iron‐rich atmospheric dust in the austral summer, we calculate forward trajectories from continental sources in the Southern Hemisphere between 2007 and 2015. A statistical comparison between trajectory patterns and maps of chlorophyll‐a, an indicator of ocean productivity, shows a significant positive correlation in ocean areas between 45°S and 65°S, consistent with the dust deposition hypothesis. Likewise, considering the area south of 45°S, while excluding the coastal belt of Antarctica, a positive correlation is also found. These results suggest the existence of two potential sources of bioavailable iron to the Southern Ocean that determine its productivity patterns: aeolian transport from dust sources into the open Southern Ocean and coastal sediment and upwelling in the coastal Antarctic Ocean.