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A mysterious die-off is occurring in the Caribbean Sea. First detected in January of 2022 and since spreading across the region, sea urchins are losing their spines and detaching from their anchors but until now, no one has known why. We'll explore disease and the marine ecosystem in the U.S. National Science Foundation's "Discovery Files."

Long-spined Sea urchins serve as vital herbivores in a coral reef ecosystem by keeping in check the algae which would outcompete and kill the coral populations if left unchecked. In the 30 years since the last major die-off event, some 80% of coral reef cover was lost in the Caribbean and the population of long-spined sea urchins have only recovered to a small fraction of its previous number.

An international team collected specimens from across the Caribbean and delivered samples to NSF supported researchers at Cornell University and partner institutions who were able to identify the microscopic, single-cell microbe responsible for the latest severe mortality event. The ciliate philaster is known to infect fish, but this is the first time it's been associated with urchins.

While there is currently no way to directly treat the infection, identifying the parasite is helpful for preventing further spread in the long spine sea urchin population.

These urchins are currently being raised for restocking efforts so that they might return to their essential role in maintaining coral health in the marine ecosystem.

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