“This was far more in depth than I had ever gotten. It was a lot of trial and error. I hadn’t expected to be so much on my own, so it took me a while to get used to that, to make the responsibilities my own. It was challenging, but exciting at the same time.”

Caitlin Del Sesto
University of Rhode Island
Master’s, biological and environmental sciences
Lab animal technician, URI

As a University of Rhode Island (URI) senior, majoring in marine biology, Caitlin Del Sesto ran into a serious roadblock with a project for her invertebrate zoology class — the sea stars she collected kept dying.

After put in a tank, they turned limp and slimy, and developed white lesions. Finally, their bodies disintegrated and they died. She couldn’t get her project started.

At the same time, Rhode Island NSF EPSCoR scientists around the state — Gary Wessel, Brown University; Marta Gomez-Chiarri, URI; Roxanne Smolowitz, Roger Williams University; and Ed Baker, the Marine Science Research Facility (MSRF) on the URI Bay Campus — each in their own way stumbled across what was amounting to a massive die-off of sea stars along the northern Atlantic coast.

Wessel could not secure sea star specimens for his research on how they reproduce. Gomez-Chiarri, Del Sesto’s major advisor, saw dead sea stars washed ashore on a Jamestown beach. Smolowitz fielded a call from colleagues about the wasting disease. Baker observed mass strandings at the Bay Campus pier.

Sensing an opportunity to collaborate through the RI EPSCoR community and leverage the depth of scientific expertise, Wessel pulled the team together for a 2013 RI Science and Technology Advisory Council (STAC) grant that pooled the talents of the researchers and provided an unparalleled opportunity for Del Sesto, who came on board as she pursued her master’s degree.

“After my undergraduate studies, I was really unsure about what I wanted to do,” she says. “This not only gave me time, but also hands-on experience developing an experiment from the ground up.”

Del Sesto says she learned how to establish project protocol, set up an experiment, and define the disease, ultimately giving her a much clearer idea of her skills and qualifications. Although she gained experience during her undergraduate years, the sea star project pushed her into new territory:

“This was far more in depth than I had ever gotten. It was a lot of trial and error. I hadn’t expected to be so much on my own, so it took me a while to get used to that, to make the responsibilities my own. It was challenging, but exciting at the same time.”

And, she adds, if not for the STAC grant, she would not have been able to conduct the research for her graduate degree. The project also gave her access to learn from the team of Rhode Island researchers with expertise that spanned multiple fields.

Although there were instances of sea star die-offs before, none of the events lasted as long, spread as extensively, or turned up on both east and west coasts. In 2014, scientists identified a sea star associated densovirus (SSaDV) linked to the wasting disease in the West Coast sea stars. Del Sesto says she investigated whether the same viral sequence existed in the East Coast species. She did find a portion that matched, but there wasn’t enough to provide a definitive answer.

“From the sample we analyzed, there isn’t a relationship,” explains Del Sesto. “Yes, we find the sequence, but we find it in healthy sea stars, we find it in sick ones, we find it in ones not exposed to the disease. We even find it ones we just took in from the wild.”

To draw any more conclusions, more analysis is needed, Del Sesto says. The method used to identify the virus indicated whether the virus was there. The next step would be to determine what, if anything can activate the virus.

Although the answer remains elusive, Del Sesto says the Rhode Island research made valuable advances toward understanding what might lurk behind the phenomenon of periodic sea star die-offs. The work defined clinical signs and the progression of wasting; there is a new body of tissue analysis that can bring greater context to the next episode.

In October 2015, there continued to be instances of die-offs in holding tanks and scattered reports of wasting. Now, however, the population seems to be rebounding. The explanation could be the species developed resistance or maybe there are places where the sea stars remain scarce. The die-off might be part of a regular ebb and flow, although the range this time astounded scientists.

Whatever the culprit, Del Sesto says, marine diseases only will become increasingly prevalent as climate change and other factors alter the marine environment.

Story and photos by Amy Dunkle | RI NSF EPSCoR