TAMPA, Fla. — Long-spined sea urchins, from the Caribbean to Florida, were dying off in droves last year, putting scientists in a race against time to find the culprit.

Now, University of South Florida scientist has solved the case, discovering the single celled organism responsible for the sea urchin deaths.

USF professor Mya Breitbart, whose work focuses on microbiology, says she was contacted about the sea urchins and immediately got to work assembling a team of researchers.

“In areas where we saw this disease, it killed up to 98% of the urchins in just a matter of days,” Breitbart said.

Various methods of testing revealed the presence of a specific kind of ciliate in all of the diseased sea urchins, but not the healthy ones.

“A ciliate is a single celled micro organism — it’s about a 10th of a millimeter long and it’s covered in lots of hair called cilia, which is how it eats and moves around,” Breitbart said.

The team then cultured the suspected ciliates in the lab at USF and tracked their effect on sea urchins in a controlled setting.

“At that point we had definitively shown that the ciliate caused the disease, and that, to me, I think it's a once in a lifetime moment,” Breitbart said.

There was a similar massive die-off of sea urchins in the 1980s, the cause of which is still unknown. Breitbart says her discovery decades later in a different case will help move research forward into the realm of prevention.

“Having that answer is extremely exciting, but it leads to a lot more questions now,” she said.

Experts say sea urchins play a vital role in the marine ecosystem they inhabit — they are herbivores that feed on algae, which grows on already threatened coral reefs, helping to keep the delicate balance between the two. Breitbart said the most recent sea urchin die-off slowed down by the end of last year, though some recent reports have shown it starting up again in some areas.

When it comes to prevention measures, Breitbart said researchers will now start looking at the conditions in which the ciliate lives and the potential for an safe water treatment to stop it.