Scientists discover why sea urchins are dying from the US to the Caribbean

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Marine biologists at a Florida university say they have solved the mystery of a mass die-off of sea urchins from the United States to the Caribbean.

Scientists blame a microscopic single-celled parasite for the death, which took hold early last year. Urchins affected by Diadema antillarum lose their spines and suck, then succumb to the disease.

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The researchers, from the University of South Florida (USF) in Tampa, also suspect that the organism, a ciliate known as a philaster, may have been responsible for killing up to 98% of sea urchins in a similar episode in the US region. 80s.

“I was like, ‘Yeah, we have to figure this out,’ because in that 1980s extinction, just the loss of this urchin species completely changed the fate of coral reefs,” Mya Breitbart, professor of biological oceanography at USF, said. told the Tampa Bay Times about the day she was asked to research the death in March of last year.

Breitbart and a team made up of scientists from Cornell University and the US Geological Survey solved the case within four months. Their study was published last week in the scientific journal Science Advances.

They identified the culprit by collecting samples from 23 sites in the Caribbean, including Aruba, the US Virgin Islands and Puerto Rico, and looking at organisms attached to sea urchins, known as the “lawnmowers” of coral reefs for their ability to consume algae that cause decay.

They were able to prove that the philaster was to blame by placing the organism in tanks with healthy, lab-grown urchins and watching about 60 percent of the sample die with the same symptoms exhibited in the marine environment.

Breitbart said what surprised them most was how quickly they were able to locate the prime suspect.

“All of us on our team have been working on marine disease for a long time and this just doesn’t happen. This is really unprecedented to understand that,” she said.

The 1980s cause of death was not established at the time and may never be known, Breitbart said, because no samples from that outbreak yet exist.

But scientists have identified similarities between the two events and say the result is the same: coral reefs clogged with algae and starved of nutrients, further adding to their precarious state.

Coral reefs in the Caribbean were already suffering from the rapidly spreading and highly contagious stony coral tissue loss disease, scientists warned more than a decade ago that the entire reef system was in danger of collapse.

While there is no known method to get rid of philaster or protect sea urchins from it, Breitbart said he hopes further research will provide a breakthrough. His team in Tampa has set up a laboratory farm to study the organism, which is not harmful to humans.

“We are excited to share this information with everyone from reef managers to other scientists so we can explore it further and try to stop its spread,” he said.

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