Tending to Tidy Island
EPA grant to allow New College to study best ways to restore mangroves
by David Gulliver
For four decades, New College of Florida has had a special but nearly forgotten connection with a place called Tidy Island.
Dr. John Morrill, the legendary NCF biology professor, conducted consulting work with the developers of the peninsula in northern Sarasota Bay. That led to most of the land, some 175 acres, being signed over to the New College Foundation as a preserve.
Some of Morrill’s students worked with him on the consulting, and many went on to do thesis projects and independent studies on aspects of the island. Over the years, though, interest waned, and for 20 years the College has had little interest in the island.
But that has all changed, and once again New College professors and students will be deeply involved in Tidy Island. New College has received a $294,198 grant from the U.S. Environmental Protection Agency to identify the best methods for restoring Tidy Island’s mangrove habitat.
Tidy Island has the most extensive mangrove habitat remaining in Sarasota Bay. The three-year grant centers on removal of invasive plants along ditches dredged through the area for mosquito control – and now are important habitats for fish and other marine life.
New College scientists, working with teams of students, will test two methods of disposing of the wood from the invasive plants. They will analyze how each method affects carbon in the environment, quality of the water and the use of the habitat by fish and other economically important marine species. They also will monitor mangroves to see how they respond to removing invasive plants.
The project’s goal is to identify the best ways to restore mangrove habitats, so that future projects in Florida and elsewhere will be optimal for both the mangroves and the marine life in the ecosystem.
The lead investigators on the grant are Drs. Brad Oberle and Jayne Gardiner, both assistant professors of biology at New College. Oberle is a botanist whose research focuses on forests, carbon sequestration and climate change. Gardiner specializes in fishes and her recent research has focused on shark nursery habitats.
“What our project is all about is exactly what to do with that wood, to figure out how it affects the carbon at Tidy Island, and how it affects the fish that actually use the mosquito ditches,” Oberle said.
The project is believed to be the first of its kind in Florida. There have been a handful of studies looking at the effects of mangrove restoration, Gardiner said, but monitoring generally begins after the work was completed and it is rare to have the opportunity to collect baseline information beforehand.
“It’s rare to have funding opportunities that give you what we have here, which is an opportunity to look at what we’re doing, and to take the time after we’ve done the restoration activity to look at how we’ve impacted things,” Gardiner said.
Sandra Gilchrist, professor of biology and director of New College’s Pritzker Marine Biology Research Center, is assisting with the project. The Sarasota Bay Estuary Program also is a partner in the grant.
Team members are now preparing final documentation for EPA. They expect to begin collecting baseline data this fall, with the restoration to occur in the summer of 2019. Then they will track the restoration’s effects for a year.
New College worked with Tidy Island residents and the Sarasota Bay Estuary Program to develop the plans for the restoration and environmental monitoring. The grant, from EPA’s Gulf of Mexico program, covers the cost of contractors removing the invasive plants, water quality monitoring stations and other equipment, and stipends for New College personnel.
Team members say the project will benefit not only Tidy Island, but everyone from students to the biology research community and businesses like environmental contractors.
“We get to restore Tidy Island, the whole reason this got on the radar in the first place. We get to do it as both teaching and research,” Oberle said.
“Students are going to be really involved directly in doing the research, and then indirectly, in thinking about the results in how that makes a difference. And we can share the results with the ecological restoration community, so that when they’re trying to fix mangroves like this, they have a more quantitative sense of the impacts of their choices.”
The project began with the Estuary Program’s plans to start restoring Tidy Island’s mangroves. Julie Morris – one of Morrill’s Tidy Island students, and now NCF’s associate vice president of academic affairs – has worked with the Estuary Program and shared the plans with the professors, who saw the potential for a unique research project.
The project begins with mangroves, a highly visible symbol of Florida’s natural coastline, but delves into perhaps the biggest issue in environmental science.
“Mangroves are this gateway between forests and the open ocean,” Oberle said. “They’re really productive, and the cool thing is they’re productive in the ways that forests are usually productive – that is, you have trees that grow, they store a lot of carbon, that carbon is now out of the atmosphere, and it’s in trees, leaves and soil.”
Here is where recent Florida history comes into play, and a 1984 thesis by NCF student Beth Hope Hussey provides details.
While there is evidence of Native Americans living on Tidy Island, from 500 to 1000 CE and 1200 to 1400 CE, modern Americans first settled there around 1890. Cornelius Thigpen, the first recorded resident, sold the peninsula around 1911 for $68.84, and that buyer sold it in 1913 for $3,500.
By 1980, developer Randy Chastain bought the property for $1.5 million, and today a single-family home there is listed at $2.4 million (though condominiums sell for around $500,000).
As the bayfront land was developed, builders did what was standard practice in Florida, dredging ditches to allow water flow and, they hoped, reduce mosquito populations.
In aerial photos, Tidy Island resembles a green quilt, with slightly darker green lines criss-crossing it, and along the lines are lighter-colored circles. As he explains, Oberle rolls up his sleeve and points to a scar on his elbow.
The scar line is the ditch, he explains, and the round marks alongside it -- suture holes -- are spoil piles, where workers dumped dirt from the ditches. Longer light-green lines are spoil mounds, where the dumped soil makes a continuous ridge.
The piled-up disturbed soil becomes an “absolute magnet for invasive plants – some of the nastiest ones around Sarasota,” he said. Most are Australian pine, Brazilian pepper and carrotwood trees, which grow almost as fast as mangroves, tolerate extreme conditions and spread easily.
“That raises an interesting question about habitat value,” he continues. “So we’re making habitat that is great for these fast-growing invasive plants. People don’t like them because they’re non-native. There are policies about trying to remove them, which attracted the attention of the Sarasota Bay Estuary program.”
“But if you return to the climate action plan, we like Tidy Island because it stores so much carbon. And if you look at these plants, they are huge. So if we restore the habitat, that means we kill the plants and all that carbon winds up going back into the environment.”
So what to do with the wood? You could burn it, probably the worst solution from a carbon sequestration view. You could cart it off site, but that removes it from the ecosystem. You could chip it, but then where does it go?
The experiment will test two options. Along one mosquito ditch, they will chip it and spread it along the spoil ridge, to prevent invasives from returning. At another mosquito ditch, they will test what happens when the chipped wood goes into the mosquito ditch itself.
That’s where Gardiner’s work comes in. She has extensive experience in conducting fish surveys, and uses technology that allows tagging and tracking of baby fish – using the sort of microchips that a veterinarian places in a dog or cat.
That technology was developed in the Pacific Northwest to track salmon populations, but Florida scientists have adapted it to track fish in salt water, moving in tidal creeks.
“If these ditches are like others in lower Tampa Bay, we’re going to be encountering tens of thousands of fish during the course of the study,” Gardiner said. They plan to tag a subset, particularly species like snook, red drum, spotted sea trout, and snapper, which have commercial and recreational significance.
The scientists don’t have a prediction for the outcome of the experiment. The wood chips added to the ditch could decompose and feed detritivores, tiny invertebrates that eat decaying organic matter – providing a rich food source for the young fish, Gardiner said. Or it could lead to a bacterial bloom, consuming oxygen and degrading the habitat.
The grant will allow them to install water quality sensing stations, Gardiner said, allowing them to carefully monitor flow rates, salinity, turbidity, dissolved oxygen and fluorescent dissolved organic matter, a proxy for carbon movement.
The grant also provides for solar-powered antennas that act as a high-tech gate, tracking the microchipped fish as they move in and out of Sarasota Bay and the Tidy Island mangrove habitat.
In essence, the grant creates a living laboratory, with immense benefits for New College students.
“We’re going to be involving students in all of the work that we’re doing up there, through tutorials and classes and thesis projects and ISPs,” Gardiner said. “They’ll be helping with all aspects – pulling those seines, identifying those fish, measuring them, tagging them, interpreting data on fish movements.” They also expect to share data and methods with Dr. Gilchrist’s long-running PUSH/SUCCESS summer program for disadvantaged students.
After the project ends, the equipment will be available for longer-term studies at the site or other projects in the region. Oberle and Gardiner predict that dozens of students will use the project as the basis for independent study projects and senior theses for a decade – producing research relevant to real-world policy applications.