As a source of strange and exotic phenomena, the oceans appear limitless. A while ago we took a look at abyssal plains, which cover more than a third of the Earth’s surface (20 July, p 49). Here’s another one that caught our eye: OMZs, or oxygen-minimum zones.
OMZs are just what you’d expect: bodies of water where oxygen levels are considerably lower than normal – less than 0.5 millilitres of oxygen per litre of sea water, compared with the average of 7. Scientists have found these zones several hundred metres down off the west coasts of North, Central and South America, off the west coast of southern Africa, in the Arabian…
