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USF marine scientists are among a group of researchers acting quickly to find a sea urchin killer

Two long-spined sea urchins sit underwater in front of a stone. One is missing a large number of spines.
Ian Hewson
Cornell University
A healthy long-spined sea urchin and a sick one, missing half of its spines, float underwater.

An alarming number of sea urchins dying in the Caribbean and along Florida's east coast had scientists wondering why.

It first began in January 2022 — a massive number of long-spine sea urchins in the Caribbean began dying off from an unknown cause.

Over time, the urchin killer moved throughout the ocean, leaving places like Jamaica and the east coast of Florida in a similar situation.

Sea urchins fulfill an integral role in their ecosystem, and with such an important species at risk, it wasn't long before researchers got to work on figuring out what was causing the die-off.

Within four months, a remarkably short time frame, a team of biologists was finally able to put a name on the culprit. By replicating the conditions of the ocean in a lab, the researchers found the killer to be a single-celled organism called a ciliate.

The parasite was responsible for killing as much as 98% of the sea urchin population in affected areas.

Mya Breitbart is a distinguished professor at the University of South Florida College of Marine Science. She helped spearhead research on the ciliate, assembling a team of scientists from around the state, including USF graduate student Isabella Ritchie.

Despite their discovery, Breitbart is still worried.

"We still have a ton of questions. Was this a new pathogen that just appeared in the region?" She said, "And if so, where did it come from? How did it spread? Or was this a microbe that was already present on the coral reefs?"

What biologists do know is the important part sea urchins play. Urchins naturally feed off of algae and prevent it from covering coral reefs.

With such a major loss of the sea urchin population, biologists fear for the already endangered reefs.

"The coral reefs are already under a lot of different assaults, nutrient pollution, global warming, diseases, all sorts of things," added Breitbart.

A similar event happened 40 years ago, with massive sea urchin deaths. Officials said that within a few months of those die-offs they were already noticing algal growths on coral reefs.

The cause of the earlier deaths was never uncovered — but Breitbart said that there is no definite connection between the two events.

Thomas Ouellette is is the WUSF Rush Family / USF Zimmerman Radio News intern for spring of 2023.