During the spring and early summer, there have been clear skies and persistent heat in north-western Europe, providing ideal conditions for large and persistent blooms of phytoplankton to thrive around the UK and Ireland.
Phytoplankton are tiny, plant-like organisms that often float near the surface of the ocean and turn sunlight and carbon dioxide into sugars and oxygen.
Then, they become food for the grazing zooplankton, shellfish, and fin fish. They also play an important, but not fully understood, role in the global carbon cycle, taking carbon dioxide out of the atmosphere and sinking it to the bottom of the ocean.
Last week NASA’s Operational Land Imager identified a massive phytoplankton bloom off the coast of south-west England and the next day another piece of kit on the Terra satellite saw the same bloom in a wider context with more phytoplankton in the North Sea.
NASA said: ‘The milky, light-coloured waters are probably filled with coccolithophores, which have calcium carbonate plates that appear chalky white when amassed in great numbers.
‘The brightness of the color may reflect the density of the phytoplankton, while the various swirls and shapes trace the intricate movements of currents, eddies, and tides.’
A marine biologist at the University of Plymouth, Abigail McQuatters-Gollop, said coccolithophore blooms are regular in the English Channel, but not usually as large and intense as this.
It is thought that the particularly sunny and warm May this year triggered such an extraordinary bloom.
‘Understanding why we get large blooms like this is critical to developing our understanding of the ocean’s role in climate change mitigation,’ Ms McQuatters-Gollop told NASA.
‘Understanding how climate change and ocean acidification affect coccolithophores will also help us understand what future marine food webs might look like.’