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MEDIA: “Suffocating seas...” Prof Ana Queirós on marine heatwaves and ‘seabed hypoxia’
11 May 2024
‘From Australia to Tanzania, coral bleaching is becoming more frequent and extensive, notes Ana Queirós, a marine and climate change ecologist at Plymouth Marine Laboratory in the UK.
Unlike marine organisms such as fish, corals can't move when the ocean around them experiences a heatwave, Queirós explains. With many areas of ocean now undergoing seabed heatwaves, the impact can be "terrible".
More generally, ocean warming is also depriving marine life of vital oxygen and nutrients. Oxygen is less soluble in warmer waters, and since surface water warms up before water lower down, it also becomes less dense, making it harder for water at the top and bottom of the ocean to mix. Without this mixing, nutrients deposited at or near the seafloor struggle to make it back to surface waters, where they are needed by microorganisms such as phytoplankton that form base of the foodweb. In turn, oxygen from surface waters cannot reach the deeper layers of the ocean.
The outcome, says Queirós, is more frequent seabed hypoxia (low oxygen) events, leading to die offs on the ocean floor. As well as the expansion of "oxygen minimum zones", in which seafloor areas are depleted in oxygen for long periods.’
Read the full article on the BBC website >>