A matter of light and depth

Sarasota Bay is nothing less than idyllic. Its azure beauty has launched a thousand postcards. But that’s just what you see on the surface. Gerardo Toro-Farmer, Ph.D., is more interested in what’s going on below the surface.

Toro-Farmer is an oceanographer and assistant professor of coastal and marine science at New College. The living sea is both his subject matter and his classroom. Since 2018, he has been studying the effects of light quality on Sarasota Bay’s seagrass beds.

Why is seagrass so important?

“For many reasons,” Toro-Farmer said. “They’re at the heart of marine ecology in shallow, salty waters near the shore and along the continental shelf.”

According to Toro-Farmer, seagrass stabilizes the sea bottom. It provides food and shelter to a host of creatures at both ends of the food chain, from manatees and sea turtles to sea urchins and fishes of all sizes. It also functions as the “lungs of the sea,” releasing oxygen both for sea creatures and land-dwellers alike—our species included.

The bottom line?

“Seagrass is good for human beings,” he said. “But human beings aren’t always good for seagrass.”

Toro-Farmer explained that seagrass is an underwater plant that needs sunlight to survive. For seagrass, murky water is the equivalent of a cloudy day. Bad water quality decreases the available light seagrass needs for photosynthesis. Mother Nature is sometimes responsible. But humanity is usually the culprit.

Our species muddies the water in many ways. Dredging fills the bay with silt. Stormwater runoff brings pollutants—including nutrients, which contribute to algae blooms. Boat propellers can also physically gouge seagrass beds, creating nasty scars that take years to heal.

The list of anthropogenic pressures is long; but without hard data, it’s anecdotal evidence, not proof. And that’s what Toro-Farmer’s current project, Effects of Light Quality on Seagrass Beds of Sarasota Bay, is all about.

“I’m creating a high-resolution temporal dataset,” he explained.

In layman’s terms, Toro-Farmer measures the quality of light in different regions of seagrass in Sarasota Bay. He also measures the health of each region of seagrass. It’s not a sporadic effort, but an ongoing documentation over time.

If seagrass is the heart of this ecosystem, Toro-Farmer is measuring the heartbeat.

Practically speaking, that’s impossible in a classroom. You need to go out in the field (or, in this case, the water). That means boat trips, occasional scuba diving and plenty of sunblock. It’s exhilarating. But it’s also hard work.

Two dedicated New College interns: Lexi Fox, an environmental studies student; and Maria Guardado, a marine biology and philosophy student; made the job a lot easier.

“Lexi and Maria are extremely smart, and enthusiastic about our hands-on experiences,” Toro-Farmer said. “I thought the pandemic would force me to cancel their summer internship—and they reacted like I was canceling Christmas. They said, ‘We’ll do it, masks and everything.’ And that’s what we did. They’ve accompanied me on the bay for hours and hours, collecting data.”

That may sound like fun—and it was. But there’s a serious purpose behind it.

Toro-Farmer originally gathered his field data in the summer. He increased his data-collection frequency to monthly, and then weekly reports. He now combines that onsite data with information from a range of other sources.

The result is a high-resolution data set being collected over nearly three years, connecting the dots between underwater illumination and seagrass health in Sarasota Bay. What role does humanity play? What impact do our sewage spills and dredging projects have? Now that the record exists, a correlation can be established. It isn’t anecdotal evidence anymore—it’s established scientific fact. And it’s also a call for change.

Ultimately, that’s the whole point. The long-term goal of Toro-Farmer’s study is to influence public policy and individual behavior.

“Real-life application is the aim of most scientific studies,” he said. “What are people doing to the seagrass of Sarasota Bay? This data eliminates the guesswork. It’s vital information for any future management plan.”

Su Byron is the communications specialist for the New College Foundation.