Gulf of Oman has enormous dead zone severely depleted of oxygen

The Arabian Sea’s long-standing zone of oxygen-depleted waters now extends into its northwest branch, the Gulf of Oman, creating the largest and thickest dead zone in the world, report researchers from the University of East Anglia and Sultan Qaboos University. The team found that oxygen levels in the gulf have fallen dramatically, and the dead zone—where the oxygen concentration is less than 2 µmol/kg—has expanded since data were last collected in the 1990s. Piracy and political tensions have impeded ship-based scientific work in the gulf, so researchers employed underwater robots to collect data used in their analysis (Geophys. Res. Lett. 2018, DOI: 10.1029/2017GL076666).