Massive algae bloom in the Yellow Sea

Today’s Image of the Day from NASA Earth Observatory shows the largest bloom of algae ever recorded in the Yellow Sea off the coast of Qingdao, China. The photo was captured on June 19, 2021, with the Hawkeye sensor on the SeaHawk CubeSat.

According to NASA, the algal species in the image is Ulva prolifera, a common green seaweed that is not toxic to people or marine life. Also known as “sea lettuce,” this seaweed is edible and nutritious. However, large amounts of decaying algae can deplete water of oxygen and kill fish. 

Lin Qi, a remote sensing and marine scientist at University of South Florida (USF), explained that blooms of Ulva prolifera typically start showing up in the western Yellow Sea in May, peak in June, and persist into July or August. 

Chuanmin Hu, who is also a marine scientist at USF, noted that most researchers agree that blooms of U. Prolifera originate around the vast aquaculture operations to the south off of Jiangsu Province. 

“What’s really unique in this image is its optimal combination of coverage and resolution,” said Hu. 

“There are other satellite sensors that show the same bloom, but they are either too coarse in resolution or too narrow in coverage (with the exception of Sentinel-2 sensors). The HawkEye image shows the U. Prolifera slicks so vividly in one image, which can certainly reduce uncertainties when estimating bloom size.”

Image Credit: NASA Earth Observatory 

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By Chrissy Sexton, Earth.com Staff Writer