A graduate student studying dolphin behavior in Florida Bay hopes his research can help scientists better understand the health of the Everglades ecosystem and the effects of restoration efforts.
João Valle-Pereira, a Ph.D. student at Oregon State University and a Micky and Madeleine Arison Family Foundation ForEverglades Fellow with the Everglades Foundation, joined Good Morning Keys on Keys Talk 96.9/102.5FM this morning to talk about the program.
Valle-Pereira is researching a hunting technique known as mud ring feeding.
The technique involves dolphins using their tails to stir up sediment on the shallow seafloor, creating a circular wall of mud around a school of fish. The trapped fish attempt to escape by jumping out of the water, where the dolphins wait to catch them.
“It honestly just looks like a magic trick,” Valle-Pereira said.
Valle-Pereira, who is originally from Brazil, studies animal culture, including how dolphins learn specialized skills from one another and pass those behaviors along.
He said mud ring feeding is not practiced by every dolphin in Florida Bay. Instead, the behavior appears to be concentrated among certain individuals that tend to associate with one another.
“It’s basically not just an instinct. It’s something they learn from the right friends, I guess,” Valle-Pereira said.
To study the behavior, researchers travel by boat across shallow-water areas, looking for the telltale rings of mud created during feeding. They photograph dolphins’ dorsal fins to identify individual animals, record their behavior using cameras mounted on tall poles, listen through underwater microphones known as hydrophones and measure environmental conditions.
Valle-Pereira said the work requires patience and early mornings, but it provides an opportunity to observe the dolphins’ specialized hunting strategies firsthand.
The research also highlights the connection between Florida Bay and the broader Everglades ecosystem.
Fresh water flowing south through the Everglades eventually reaches Florida Bay, influencing salinity levels and the health of seagrass and fish populations. Those conditions, in turn, affect the dolphins that depend on the bay for food and habitat.
“The dolphins are at the very end of the Everglades plumbing, so to say, and their food and habitat depend on what happens way upstream,” Valle-Pereira said.
Because mud ring feeding depends on suitable shallow-water habitat and healthy fish populations, changes in the behavior could provide clues about changing environmental conditions.
Valle-Pereira described dolphins as a “living report card” for the bay, explaining that the presence of the behavior can help researchers assess whether conditions remain suitable for wildlife.
“If the behavior starts maybe disappearing from places, that’s a warning. The habitat is changing,” he said.
He said the findings could also help communicate the importance of Everglades restoration to policymakers by showing how changes to freshwater flows upstream affect wildlife farther downstream.
The Everglades Foundation’s ForEverglades Research Enhancement Grant Program has supported more than 100 master’s and doctoral students since 2008, funding research intended to advance Everglades restoration and protection.
Valle-Pereira said the fellowship made it possible for him to move beyond computer-based research and study the dolphins directly in Florida Bay.
“For me, it was a game changer,” he said. “It actually got me out in the water in Florida Bay to study this behavior firsthand.”
The researcher has completed one field season with support from the foundation and is also working with a collaborator’s historical data dating to the early 2000s. He said another field season is planned for the winter to examine seasonal differences and determine whether researchers encounter some of the same dolphins observed in earlier years.
People interested in learning more about the research can visit EvergladesFoundation.org, where a blog post and video feature the project and footage of mud ring feeding.