Scientists identify 2022 sea urchin killer
The mass die-off of the long-spined sea urchin -- a loss that threatens
the health of coral reefs from the Caribbean to Florida's east coast -- was caused by a one-celled organism called a ciliate.

Date:
April 19, 2023
Source:
University of South Florida
Summary:
A team of researchers has identified a single-celled organism
called a ciliate as the cause of a massive die-off event to a
marine animal vital to coral reef health.


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FULL STORY ==========================================================================
The search for the 2022 killer that decimated the long-spined sea urchin population in the Caribbean and along Florida's east coast is over. A
team of researchers organized by Mya Breitbart, Distinguished University Professor at the University of South Florida's College of Marine Science, identified a single-celled organism called a ciliate as the cause of a
massive die-off event to a marine animal vital to coral reef health.


========================================================================== Their findings were reported in Science Advances.

"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.

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.

"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.

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?
"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. "We're 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 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.

* RELATED_TOPICS
o Plants_&_Animals
# Marine_Biology # Fish # Sea_Life # New_Species
o Earth_&_Climate
# Coral_Reefs # Ecology # Oceanography #
Environmental_Awareness
* RELATED_TERMS
o Coral_reef o Coral_bleaching o Great_Barrier_Reef o Coral o
Permian-Triassic_extinction_event o Red_tide o Dinoflagellate
o Artificial_reef

========================================================================== Story Source: Materials provided by University_of_South_Florida. Original written by Kristen Kusek. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. 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.

A scuticociliate causes mass mortality of Diadema antillarum
in the Caribbean Sea. Science Advances, 2023; 9 (16) DOI:
10.1126/sciadv.adg3200 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/04/230419142739.htm

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