Conditions of low dissolved oxygen in shallow-water ocean and freshwater environments. There is no universal threshold for hypoxia. A value around 60 μmol kg has commonly been used for some estuarine systems, although this does not necessarily directly translate into biological impacts. Anoxic conditions occur where there is no oxygen present at all. See also Eutrophication.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report