Discovery: Why Strange, Chalky Swirls Cover the Southern Ocean

By Rafi Letzter, Staff Writer | December 1, 2017 01:53 pm ET

Behold the Great Calcite Belt, ring around the Southern Ocean, coverer of 16 percent of all the global seas, and shiny bloom of microscopic phytoplankton so large it's best seen from space.

Organisms called coccolithophores — tiny, single-celled photosynthesizers that are neither plants nor bacteria — dominate those microscopic swarms, researchers recently discovered.

A team of scientists took two cruises, each one month long, through the great belt in the Southern Hemisphere summers of 2011 and 2012. The researchers went there to study the ocean chemistry that gives rise to an annual algal bloom, as well as the swarms of algae that make it up, reporting their results Nov. 7 in the journal Biogeosciences. [Gallery: Scientists at the Ends of the Earth]

Coccolithophores cover their bodies in plates of chalk (calcium carbonate) as they grow. When they concentrate together in the ocean, that chalk reflects light back into the sky, giving the water a milky-blue color. The result, when seen from above, looks as if Dr. Seuss ran into Vincent Van Gogh, leaving behind a quirky cast of blue-green iridescent swirls on the sea.

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