February 29, 2024

Sea Urchin Killer Identified: Scientists Unmask the Microscopic Menace Behind Massive Die-Off Event

A scuticociliate, a single-celled organism, has been identified as the cause of the 2022 mass die-off of long-spined sea urchins in the Caribbean and Floridas east coast. These urchins are essential for reef health, and the discovery raises questions about the ciliates presence, development conditions, and possible effect on other types. Picture of Long Spined Sea Urchin (Diadema antillarum).
The mass die-off of the long-spined sea urchin– a loss that threatens the health of coral reefs from the Caribbean to Floridas east coast– was triggered by a one-celled organism called a ciliate.
The look for the 2022 killer that annihilated the long-spined sea urchin population in the Caribbean and along Floridas east coast is over. A team of scientists arranged by Mya Breitbart, Distinguished University Professor at the University of South Floridas College of Marine Science, determined a single-celled organism called a ciliate as the cause of an enormous die-off event to a marine animal important to coral reef health.
Their findings were reported on April 19 in the journal Science Advances.

Ciliate culture seen under the microscopic lense. Credit: Mya Breitbart USF College of Marine Science
” Were beyond enjoyed get to the bottom of the 2022 secret and a bit shocked we did it so quickly,” stated Breitbart, senior author on the Science Advances study and an expert in marine genomics. “We had a fantastic team in location and the tools required to do the ocean science equivalent of a forensic investigation.”
Ciliates are tiny organisms covered in hair-like structures called cilia that assist them eat and move. They are discovered almost anywhere there is water and a lot of are not disease-causing representatives. This specific types of ciliate– called a scuticociliate– has actually been linked in die-offs of other marine species, such as sharks, in the past.
Picture compilation showing the same sea urchin prior to and after infection with the ciliate in the USF fish tank research study facility. Credit: Makenzie Kerr USF College of Marine Science
Taking a look at urchins collected from 23 sites in the Caribbean, the research team used a series of techniques to validate the source of the die-off occasion.
After determining the ciliate in every impacted urchin specimen utilizing genomic techniques, the team grew ciliates in the lab and performed infection experiments at the USF College of Marine Science. When the pathogen was introduced to otherwise healthy urchins in an aquarium tank, the urchins passed away within a couple of days– replicating what was happening in the ocean and confirming the ciliate as the disease source.
DaSc-affected sea urchin, Aruba, August 2022. Credit: Ian Hewson Cornell University
” Were thrilled to share this details with everyone, from reef managers to additional scientists so we can explore it even more and attempt to stop its spread,” Breitbart said.
Mya Breitbart (USF) seeing the ciliate culture by microscopy. Credit: Makenzie Kerr USF College of Marine Science
The long-spined sea urchins occupy shallow tropical waters and feed on algae that would otherwise ruin a reef. They began to lose their spines within days of contracting an unidentified illness and passed away in droves starting in January 2022.
A comparable die-off event took place in the early 1980s, which eliminated 98 percent of the long-spined sea urchin population. The culprit of that die-off stays a mystery.
Breitbart initially got the call about the unfolding die-off at the end of March 2022. She instantly assembled a team including Ian Hewson, lead author on the publication and a marine ecologist at Cornell University; Christina Kellogg, a microbiologist from the U.S. Geological Survey in St. Petersburg, Fla. who has worked thoroughly on coral reef diseases; and USF college student Isabella Ritchie.
” At the time, we didnt know if this die-off was brought on by pollution, tension, something else– we just didnt understand,” stated Hewson, an expert in illness that cause mass die-offs of sea stars, who flew from New York to the Caribbean Islands to observe the situation.
Even with the source of the mystical die-off uncovered, questions still stay. :

A scuticociliate, a single-celled organism, has been determined as the cause of the 2022 mass die-off of long-spined sea urchins in the Caribbean and Floridas east coast. Picture of Long Spined Sea Urchin (Diadema antillarum).
Ciliates are tiny organisms covered in hair-like structures called cilia that assist them move and eat. They are discovered nearly anywhere there is water and the majority of are not disease-causing representatives. This particular species of ciliate– called a scuticociliate– has actually been implicated in die-offs of other marine types, such as sharks, in the past.

” One theory we have is that the ciliate grew well under high-productivity conditions that were observed in the Caribbean when the die-off first started,” Kellogg said. “Were also curious about the fact that there is some overlap in some geographic areas where this die-off occurred and where corals are declining from stony coral tissue loss disease.”

The research study was funded by the National Science Foundation, Atkinson Center for Sustainable Futures Rapid Response Award, AGGRA, the National Oceanic and Atmospheric Administration, National Fish and Wildlife Foundation, Florida Keys Marine Sanctuary and the Florida Fish and Wildlife Conservation Commission.

Is this ciliate brand-new to the area, or was it there prior to the die-off?
If it has been there, what ecological conditions favored its development and why did it contaminate the urchins?
Can it affect other species of urchins?

Reference: “A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea” by Ian Hewson, Isabella T. Ritchie, James S. Evans, Ashley Altera, Donald Behringer, Erin Bowman, Marilyn Brandt, Kayla A. Budd, Ruleo A. Camacho, Tomas O. Cornwell, Peter D. Countway, Aldo Croquer, Gabriel A. Delgado, Christopher DeRito, Elizabeth Duermit-Moreau, Ruth Francis-Floyd, Samuel Gittens, Leslie Henderson, Alwin Hylkema, Christina A. Kellogg, Yasunari Kiryu, Kimani A. Kitson-Walters, Patricia Kramer, Judith C. Lang, Harilaos Lessios, Lauren Liddy, David Marancik, Stephen Nimrod, Joshua T. Patterson, Marit Pistor, Isabel C. Romero, Rita Sellares-Blasco, Moriah L. B. Sevier, William C. Sharp, Matthew Souza, Andreina Valdez-Trinidad, Marijn van der Laan, Brayan Vilanova-Cuevas, Maria Villalpando, Sarah D. Von Hoene, Matthew Warham, Tom Wijers, Stacey M. Williams, Thierry M. Work, Roy P. Yanong, Someira Zambrano, Alizee Zimmermann, Mya Breitbart, 19 April 2023, Science Advances.DOI: 10.1126/ sciadv.adg3200.