NASA explains bright sea off Cornwall in satellite images

02 Jul 2020 / 16:28 H.

If you’ve been looking at NASA satellite images, you’ll realize the waters off the coast of Cornwall showing up in a bright blue swathes.

According to NASA, this just means good news for marine wildlife. The image, taken with the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument abroad NASA’s Terra satellite, might be actually showing an unexpectedly large bloom of phytoplankton.

Phytoplankton are microscopic plant-like organisms that live in water and are responsible for generating half of the atmosphere’s oxygen. They also act as the base of food chains in the ocean for creatures such as zooplankton, shellfish and finfish.

"Spring and early summer 2020 brought unusually clear skies and persistent, unseasonable heat to northwestern Europe. Those conditions likely set the stage for large and persistent blooms of phytoplankton in the waters around the United Kingdom and Ireland,” NASA wrote.

According to NASA Earth Observatory, the same phytoplankton bloom can also be seen in the North Sea.

Phytoplankton bloom in the English Channel and the North Sea. Image: NASA Earth Observatory / Joshua Stevens
Phytoplankton bloom in the English Channel and the North Sea. Image: NASA Earth Observatory / Joshua Stevens

NASA explained that the ‘milky, light-coloured waters’ are possibly filled with coccolithophores which contains calcium carbonate plates that appear chalky white when gathered in great numbers.

Waters that are green may be rich with diatoms or suspended sediment but NASA added that it’s impossible to know unless a direct water sample is taken.

The brightness of the colour may reflect the density of the phytoplankton while the swirls and shapes show the movements of currents, eddies and tides.

“In May 2020, we had the sunniest month since records began. The weather was very warm, which likely caused stratification of the English Channel waters and triggered such an extraordinary bloom,” said Abigail McQuatters-Gollop, a marine biologist at Plymouth University (UK).

Stratification is the layering of the ocean in which water with different properties such as salinity, density and temperature form layers instead of mixing. This layering allows coccolithophores remain near sunny surfaces which results in longer periods of growth.

For more information, visit NASA Earth Observatory.

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