(A) Global map showing coastal sites (purple dots) and open ocean sites (red to yellow, at 300 m of depth) where oxygen levels are below 2 mg L-1 (Adapted from Breitburg et al., 2018).
(B) Change in oxygen content of the global ocean in mol O2 m−2 decade−1.
Reference: Breitburg, D., et al.(2018): "Declining oxygen in the global ocean and coastal waters." Science, Vol. 359, Issue 6371, doi:10.1126/science.aam7240.