A NASA satellite has spotted something brilliant from space: a stunning turquoise color in the Black Sea and the Bosphorus, the strait which separates Asia from Europe. The temporary turquoise was sighted by NASA’s Aqua satellite, which circle Earth looking for information about its waters. The turquoise whorls and eddies visible from space are the work of phytoplankton that have turned the water both bright and milky.
The turquoise is thought to be due to an explosive growth in phytoplankton known as a bloom. During a bloom, the tiny aquatic organisms reproduce quickly and in huge numbers. These changes are seasonal but can also take place in response to changes in nutrient availability and water temperature.
In this case, scientists think that the colorful plankton are coccolithophores. These single-celled creatures produce quite the spectacle when they gather en masse. As NASA’s Earth Observatory notes, they live on the surface in places with mild temperatures. They can multiply rapidly, outcompeting other plankton.
Since coccolithophores are surrounded by a protective shell of calcium, they reflect light and are easily spotted from space. Scientists think that the recent rapid growth in coccolithophore populations is due to climate change.
They may be tiny, but the phytoplankton have a big effect on Earth itself. First of all, they chow down on carbon—and though they also generate CO2 using compounds already in the ocean, they are thought to cool Earth by reflecting lots of light back to space.
In a release, NASA says that the bloom is the brightest since at least 2012. And locals are taking note, too: NPR’s Laurel Walmsley reports that the vivid color caused some distress to Istanbul residents, who wondered if the region’s recent 6.2-magnitude earthquake was to blame. But the blue hue is due to another force of nature—and the colorful show will likely fade as the phytoplankton die off.