The researchers, from Tampa’s University of South Florida (USF), also suspect the organism, a ciliate known as philaster, may have been responsible for wiping out about 98% of sea urchins in a similar episode in the region in the 1980s.
“I was like, ‘Yes, we have to figure this out,’ because in that 80s die-out, just the loss of this one species of urchin completely changed the fate of coral reefs,” Mya Breitbart, professor of biological oceanography at USF, told the Tampa Bay Times of the day she was invited to research the die-off in March last year.
Breitbart and a team including scientists from Cornell University and the US Geological Survey cracked the case within four months. Their study was published last week in the peer-reviewed journal Science Advances.
They identified the culprit by collecting samples from 23 sites around the Caribbean, including Aruba, the US Virgin Islands and Puerto Rico, and observing organisms attached to the sea urchins, which are known as the “lawnmowers” of coral reefs for their ability to consume decay-causing algae.