The condo towers of downtown Sarasota recede into the distance, as our motorboat tracks northward atop a shimmering Sarasota Bay.
Soon, mangroves come into focus. If you've been out on the Gulf coast, you've likely seen them. They're those long, spindly-rooted trees that look like giant spiders climbing out of the water toward land.
Abbey Tyrna leads the Mangrove Rangers for Suncoast Waterkeeper, a nonprofit environmental advocacy group. She says 90% of the mangroves in Sarasota County have been wiped out. So on a sunny afternoon, we motor northward to Manatee County. There, we come upon a pristine cluster of mangroves, part of a mitigation bank set up to compensate for losses elsewhere.
"They're critically important for holding back sediments, so that seagrass can flourish and oysters can flourish," Tyrna said. "They are the nursery for every commercial and recreational fish that you can think of. So they're incredibly important to our economy."
But no one is really sure how many are left.
She plans to take drone video of this undisturbed mangrove stand to create a baseline that will be used to compare mangroves in areas where development is affecting them.
"Because this is like the ideal condition of a mangrove," Tyrna said. "This is our reference site. Which means that we're going to compare all the other sites to this one to see how canopy density and extent match this one."
As we approach, she tells how mangroves a facing an assault on many fronts. Homeowners cut them down and environmental changes are taking a toll. Then there’s something called “coastal squeeze.”
"Meaning mangroves can't shift landward, because there's development there, so when the sea level rises, they just kind of are stuck and might drown," Tyrna said. "How does that impact mangrove health?"
There's also the dreaded "mangrove heart attack,” where one area drowns and it could take out the whole system.
"While the heart attack will be one area that drowns, due to the changes in wind patterns and water patterns due to the dying of mangroves, the whole system is now at threat," she said. "So how fast does the heart attack spread is something that we're looking to learn."
Besides being a sort of marine cardiologist, Tyrna says they are trying to make sure state and local regulations are being enforced.
"The 1997 Mangrove Trimming and Protection Act has regulations that you're supposed to uphold, and we've had 18 violations of those regulations, which means that we're putting mangroves at risk - just for view," she said.
Not far from the site that's being surveyed is a giant gap in the mangrove cover. There, newly-built condos hug the shore, The trees have been chopped to only a couple of feet high, so their view of the bay isn't impeded.
The Suncoast Waterkeepers recently started the Mangrove Rangersin response to 18 reports of illegal trimming on Sarasota Bay in the past year alone.
Homeowners cut them down so they have an unimpeded view of the water. Shortly after we left the dock, I saw one group of mangroves that had been trimmed to form a circle, like a decorative tree at a theme park.
As they prepare to launch the drone, Tyrna and volunteer Mia Esposito place it atop a paddleboard, and walk it to an oyster bar surfacing from the shallow bay.
Esposito has a civil engineering background, but decided that sitting behind a desk wasn't for her.
"I'm definitely very passionate about the water, where we live and taking pride in that, and also just being at one in nature," Esposito said.
Tyrna pulls out a laptop once they reach the oyster bar, and the drone heads for the mangroves.
"It's just like dense with branches and leaves and roots - you really can't get through there. So drones, they get us into places that we can't otherwise get," she said.
The drone will capture about 400 images of the mangroves, creating a three-dimensional portrait from above.
Once they have a baseline, the Mangrove Rangers will begin documenting other areas of the coast along Sarasota Bay. They can use those images to compare year to year how people are altering mangroves.
For now, they have about 20 volunteers, six boat operators and five FAA-certified drone pilots.
"Hopefully, this will continue," Tyrna said. "This is a one-of-a-kind program that doesn't exist anyplace else in the world. And so we're really just piloting it and figuring it out as we go, and learning new ways of observing these critical systems."
The continued existence of mangroves, she says, may just depend on it.
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