Se ha identificado un escuticociliado unicelular como la causa de una mortandad masiva de erizos de mar de larga distancia en 2022 en el Caribe y a lo largo de la costa este de Florida. Estos erizos son fundamentales para la salud de los arrecifes de coral, y el descubrimiento plantea dudas sobre la existencia de los ciliados, las condiciones de crecimiento y el impacto potencial en otros organismos. Foto del erizo de mar de espinas largas (Diadema antellarum).
La mortandad masiva del erizo de mar de espinas largas, que amenaza la salud de los arrecifes de coral desde las islas del Caribe hasta la costa este de Florida, ha sido causada por un organismo unicelular llamado ciliado.
La búsqueda del asesino de 2022 que diezmó las poblaciones de erizos de mar a lo largo de las islas del Caribe y la costa este de Florida ha terminado. Un equipo de investigadores dirigido por Mia Breitbart, distinguida profesora universitaria de la Facultad de Ciencias Marinas de la Universidad del Sur de Florida, ha identificado un organismo unicelular llamado ciliado en la mortandad masiva de un animal marino importante para los arrecifes de coral. Salud.
Sus hallazgos fueron publicados en la revista el 19 de abril. 
Ciliate culture viewed under the microscope. Credit: Mya Breitbart USF College of Marine Science
“We’re beyond thrilled to get to the bottom of the 2022 mystery and a bit stunned we did it so quickly,” said Breitbart, senior author on the Science Advances study and an expert in marine genomics. “We had a great team in place and the tools needed to do the ocean science equivalent of a forensic investigation.”
Ciliates are microscopic organisms covered in hair-like structures called cilia that help them move and eat. They are found almost anywhere there is water and most are not disease-causing agents. However, this specific species of ciliate – called a scuticociliate – has been implicated in die-offs of other marine species, such as sharks, in the past.
Photo compilation showing the same sea urchin before and after infection with the ciliate in the USF aquarium research facility. Credit: Makenzie Kerr USF College of Marine Science
Examining urchins collected from 23 sites in the Caribbean, the research team used a series of techniques to confirm the source of the die-off event.
After identifying the ciliate in every affected urchin specimen using 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 died within a few days – replicating what was taking place in the ocean and confirming the ciliate as the disease source.
DaSc-affected sea urchin, Aruba, August 2022. Credit: Ian Hewson Cornell University
“We’re excited to share this information with everyone, from reef managers to additional scientists so we can explore it further and try to stop its spread,” Breitbart said.
Mya Breitbart (USF) viewing the ciliate culture by microscopy. Credit: Makenzie Kerr USF College of Marine Science
The long-spined sea urchins inhabit shallow tropical waters and feed on algae that would otherwise destroy a reef. They began to lose their spines within days of contracting an unknown disease and died in droves starting in January 2022.
A similar die-off event took place in the early 1980s, which wiped out 98 percent of the long-spined sea urchin population. The culprit of that die-off remains a mystery.
Breitbart first got the call about the unfolding die-off at the end of March 2022. She immediately assembled a team consisting of 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 extensively on coral reef diseases; and USF graduate student Isabella Ritchie.
“At the time, we didn’t know if this die-off was caused by pollution, stress, something else – we just didn’t know,” said Hewson, an expert in diseases 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 mysterious die-off uncovered, questions still remain. For example:
- Is this ciliate new to the area, or was it there prior to the die-off?
- If it has been there, what environmental conditions favored its growth and why did it infect the urchins?
- Can it affect other species of urchins?
«Una teoría que tenemos es que el ciliado creció mejor en condiciones de alta productividad, que es lo que se vio en el Caribe cuando comenzó a morir», dijo Kellogg. «También estamos interesados en el hecho de que esta mortalidad ocurrió en ciertas áreas geográficas y que los arrecifes de coral están disminuyendo debido a la enfermedad de pérdida de tejido de coral pétreo».
Nota: Ian Hewson, Isabella D. RitchieJames S. Evans, Ashley Altera, Donald Behringer, Erin Bowman, Marilyn Brandt, Kayla A. Butt, Rulio A Camacho, Thomas O. CornwellPeter D. Countway, Aldo Kroeger, Gabriel A. Tuyo, Christopher Territo, Elizabeth Duermidt-Morey, Ruth Frances-Floyd, Samuel Gittens, Leslie Henderson, Alvin Hilkema, Christina A. Gillock, Yas Kimani A. Kitson-Walters, Patricia Kramer, Judith C. Long, Harilas Lesios, Lauren Liddy, David Marancik, Stephen Nimrod, Joshua D. Patterson, Marit Bister, Isabelle C. Rosemary, Rita Cellarez-Blasco, Moriah LB Seyam, Moriah LB Seyam C. Sharp, Matthew Souza, Andrea Valdez-Trinidad, Marijn van der Laan, Brian Villanova-Guez, Maria Villalbando, Sarah D. Van Hoyne, Matthew Warham, Tom Vigers, Stacey M. Williams, Thierry M. Trabajo, Roy B. Yanong, Somira Zambrano, Alizy Zimmerman, Mia Breitbart, 19 de abril de 2023, Avances científicos.
DOI: 10.1126/sciadv.adg3200
Esta investigación fue financiada por la Fundación Nacional de Ciencias, un Premio de Respuesta Rápida del Centro Atkinson para un Futuro Sostenible, AGGRA, la Administración Nacional Oceánica y Atmosférica, la Fundación Nacional de Pesca y Vida Silvestre, el Santuario Marino de los Cayos de Florida y la Conservación de Pesca y Vida Silvestre de Florida. Comisión.
