Masked by stinking anaerobic mud, fuggy heat, clouds of mosquitoes, and acre upon acre of flooded forest, mangroves are as mysterious as they are vital to our coasts.
"It's not for everybody,'' says Terry Doyle, a biologist formerly with Ten Thousand Islands National Wildlife Refuge. "We haven't had any sea turtle interns that come back for a second year. One season's enough.''
The Minnesota native spent a decade at the 35,000-acre refuge after 14 years in Alaska. It comes as no surprise that he's an avid birder, with a life list thus far totaling more than 3,000 species. "There is a suite of birds found only in mangroves,'' says Doyle, ticking off the mangrove cuckoo, the black-whiskered vireo, and a subspecies of the prairie warbler. "And there are a lot of other species that use the mangroves for breeding, wintering, and migration. For some species, when they're crossing the Gulf of Mexico, it's the first habitat they fall into. It's important in terms of providing food and cover for those migrating birds.''
To better explore the refuge, Doyle has towed his government-issue, 19-foot Island skiff to Goodland, a small, mangrove-rimmed town five miles east of Marco Island with a boat ramp and a busy marina. Joined by Andy From, a Louisiana-based contractor whose company was hired by the U.S. Geological Survey, we slather on the SPF 30 and motor slowly down the channel to the Gulf, passing Coon Key, Tripod Key, and Neal Key. Admittedly, they look identical: flat, unremarkable islets entirely strangled by mangroves.
Yet this humble, hardy forest is the engine driving one of the world's rarest ecosystems while also ensuring the health and welfare of offshore habitats such as seagrass beds and coral reefs. An acre of red mangroves can annually shed more than three tons of leaves. That deadfall--the foundation of a complex food web--is quickly set upon by microorganisms like bacteria and fungi. The microorganisms are eaten by larger nematodes, worms, and shrimp. These invertebrates are then consumed by fish, which are in turn taken by wading birds, ospreys, and pelicans. Additionally, the tangle of tidal roots supports oysters, sessile barnacles, and crabs. All that structure also offers shelter from predators to scores of juvenile fish species, from mullet to Goliath grouper. "It's a huge amount of shoreline," Doyle says. "It's convoluted; it wraps around itself. Along all that shoreline is habitat for fish and so many other species.''
I first began to appreciate this fact when snorkeling a small mangrove forest in Lac Bay on Bonaire, an arid island in the Dutch Antilles famed for its healthy reef and scuba diving. With plenty of hiding places and ready food, Bonaire's mangroves form a teeming nursery filled with young reef fish like French grunt and rainbow parrotfish.
Few Americans besides fishermen have seen these forests or understand their environmental value. Mangroves can be remote and inaccessible, with limited access even by boat. Unlike iconic landscapes, such as the Serengeti or Yellowstone, these habitats harbor few beguiling terrestrial mammals. Sundarbans' tigers are an exception, but the big cats are fearsome maneaters known for assailing local woodcutters and honey collectors--so the forest is not exactly visitor friendly. "If you're given an option of diving with dolphins, snorkeling a coral reef, or walking in a mangrove swamp, what would you do?" asks Robin Lewis, a Salt Spring, Florida-based expert in tropical wetland restoration. "Mangroves are not colorful. They just don't have good PR. . . . Mangroves are a hard sell. We live and die on charismatic images.''
However, the little-known secret is those cute, postcard-perfect pictures of sea turtles and sculptural corals wouldn't happen without the grunt work done by this perceived wasteland. It is no coincidence that some of the world's best diving--Australia, Belize, Palau--takes place on barrier reefs adjacent to healthy mangrove forests.
There isn't any coral reef to speak of here, but there are acres of seagrass beds grazed by hundreds of manatees. Motoring across shallow Gullivan Bay, we spot a pod of bottlenose dolphins and several marine turtles, though we're too far away to tell if they're greens or loggerheads. Overhead an American swallow-tailed kite circles effortlessly.
Doyle consults his wristwatch--we've got an incoming tide. He opens the throttle and we scoot drug-runner style through an unmarked channel, weave through a lacework of anonymous mangrove islets, then pass Dismal Key, where author Carl Hiaasen set much of his 2006 novel, Nature Girl. I'm totally lost, while Doyle navigates by dead reckoning.
"It takes a few years,'' he says. "It was such a contrast coming from Alaska, where everything is so big, where you have mountaintops. Here it's these subtle little changes and cues. Nothing's obvious.
"I know where the bad spots are, where I've gotten stuck before,'' he adds with a grin. "Those you tend to remember.''