Tracking the sounds of Sarasota Bay

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- by Abby Weingarten

Animals in Sarasota Bay make their own music. Sometimes, it’s a quiet symphony. Other times, it’s a full orchestra. And the decibel level all depends on what disturbances are occurring nearby.

The Sarasota Bay Listening Network (SBLN) has been documenting these sounds for years, and the team’s groundbreaking research (namely about the impacts of red tide) was recently published in Scientific Reports.

Entitled Passive acoustic listening stations (PALS) show rapid onset of ecological effects of harmful algal blooms in real time, the October paper in the prestigious peer-reviewed journal highlights the work of New College faculty members and collaborators with the Chicago Zoological Society’s Sarasota Dolphin Research Program (SDRP).

“We’re very excited to have this research out there and hope it encourages others to implement passive acoustic monitoring methods in their regions,” said Athena Rycyk, Ph.D., a SBLN researcher, and an assistant professor of biology and marine science at New College. “We can learn a lot about marine environments by simply listening to biological sound production. This includes being able to detect ecological changes in the environment, such as what we saw when red tide moved into Sarasota Bay.”

Rycyk, the SBLN and the SDRP team have spent countless hours studying how red tide has impacted the bay and its animals (such as fish, dolphins and manatees), using the cutting-edge technology of the PALS to track ongoing environmental changes.

The SBLN network (comprised of biologists, engineers, educators and citizens) also includes Jayne Gardiner, Ph.D., an associate professor of biology at New College; and Austin Anderson, a recent New College data science graduate student who is now a data scientist for the Sarasota-based company, Loggerhead Instruments.

The authors of the Scientific Reports paper are Rycyk; Reny B. Tyson Moore and Katherine A. McHugh, staff scientists with the SDRP; Elizabeth J. Berens McCabe, research associate/ecologist for the SDRP; Randall S. Wells, the director of the SDRP; and David A. Mann, president of Loggerhead Instruments.

In the text, it is explained in detail how PALS can be used to detect changes in fish populations (before and during a red tide event) by examining recorded sound spectrum levels.

But what are PALS, exactly? They are single-recorder hydrophones that run on solar-powered batteries (with circuit boards and processors built by Mann). The SBLN started with two of these PALS in 2018 and now has 10 stations.

“When the massive red tide hit, we started seeing on these stations the impacts of the red tide and how the sound just kind of dropped off,” Moore said. “We realized the added benefits the recorders can have—not just for studying manatee behavior—but that it could have broad-scale ecological impacts.”

While PALS are used widely in other areas of the world, Mann’s prototype (unique to the SBLN) is especially interesting and cost-effective.

“It’s a new type of setup because, before, you’d have to waterproof a recorder, anchor it in the water and retrieve it several months later. These are different because they’re land-based and have a cell modem so they can tell us what’s going on,” Rycyk said. “Every five minutes, it sends us a quick snapshot of what the sound levels are. During the red tide, these stations enabled us to very quickly see drops in sound levels. So we wanted to encourage other areas to create networks like this for establishing baseline data.”

The SBLN also uses an innovative dolphin whistle detector (made by Anderson) and is currently working on creating a manatee detector. These developments, and the recent published paper, are all part of a long-running collaboration that continues to grow larger by the year.

Over the summer, the SDRP—which is best known for conducting the world’s longest-running study of a wild dolphin population—formally partnered with New College to expand its research and education initiatives. Heidi Harley, Ph.D., a professor of psychology, a dolphin behavior and cognition expert, and the co-director of New College’s Environmental Studies Program, was instrumental in facilitating the partnership.

Based at Mote Marine Laboratory & Aquarium, the SDRP has been studying Sarasota Bay’s dolphins since 1970 (and New College scientists have studied the animals and ecology of the bay since 1960). Together, both organizations can enhance their conservation efforts, undergraduate and graduate student learning opportunities, and ongoing projects on dolphin communication and bioacoustics—and the SBLN research is a major part of that. The information and data patterns the stations have already collected will be invaluable for tracking future red tide events.

“In a healthy ecosystem, you have a lot of sounds happening and they make up this beautiful orchestra of sounds. During red tide, you have a lot of fish mortality, so the orchestra members are dying or leaving and it becomes quiet,” Moore said. “With these stations, we were able to see a full orchestra playing and then only a few orchestra members playing a few notes. We saw two-to-five decibel decrease in sound from before the bloom was present in the area to when the bloom hit, and the recovery has been pretty gradual over time. Now we’re back to a loud orchestra.”

To read the full paper, click here

Abby Weingarten is the senior editor in the Office of Communications & Marketing.