We flush tricolored and green herons as we skim across a mudflat and skip into another burgeoning gallery of red mangroves, dubbed “walking trees.’’ There’s no doubt that the salt-loving mangroves are making giant strides to colonize more of the Ten Thousand Islands in part because of rising salinity levels. Doyle estimates mangroves now comprise 70 percent of the refuge’s land mass, encroaching on more of the marshy River of Grass every year.
While the mangroves here are on a growth spurt, worldwide they’re under siege—enduring loss rates equal to or exceeding those of rainforests. According to Alfredo Quarto, executive director of the nonprofit Mangrove Action Project, more than one-third of the planet’s mangroves have been destroyed in the past 30 years, felled and filled to build shrimp farms and rice paddies, marinas and seaside golf resorts, exclusive waterfront communities and coastal highways. Every year an estimated 250,000 acres of mangrove forest—equal in area to Hong Kong—vanish; in 2006 experts grimly predicted that the ecosystem could disappear within a century. Last year the International Union for Conservation of Nature warned that one-sixth of the planet’s mangrove species were in danger of extinction.
Not only would that scenario devastate fisheries and wildlife, and ruin reefs and seagrass beds, it might also squander any hopes of environmental salvation. If impending sea-level-rise predictions due to global warming hold true, many mangroves will be lost, and with them will go their ability to sequester carbon (more than an estimated half-ton per acre annually). “If you had to pick a plant community we knew to hold carbon in large amounts, it would be mangroves,’’ says USGS ecologist Thomas J. Smith III. “Mangroves are a drop-dead, 100 percent guarantee.’’
After a circuitous, 40-minute airboat ride we approach a line of white mangroves that have migrated northward into the marsh due to changing salinity levels. There’s not enough water to support the airboat anymore, so we walk the final 100 feet through sucking mud to Ecotone Center. The men make their measurements in the stultifying heat and pile back on the airboat for another thrill ride through clusters of red mangroves and across shallow, shimmering bays. Then Doyle suddenly throttles down, and the airboat glides to a stop in a watery pan swirling with fish fry. He can’t resist the chance to see a bevy of birds, including short-billed dowitchers and black-necked stilts, American avocets and semipalmated plovers. He grabs his binoculars and notes field markings to From, an avid duck hunter. “This is one of the reasons work takes so long,” From says with a laugh. “Terry’s birdwatching.’’
We linger for perhaps a quarter-hour, admiring the mixed flock, listening to a red-winged blackbird calling from a nearby hardwood hammock, a slightly elevated island in the marsh covered in cocoplum and red maple trees. All across the wetland, tiny young red mangrove recruits are sending up shoots in the shallows. Prop roots will soon follow, then trees, and finally forest. The long march will always continue for a tree that can’t stand still.
For more information, visit Mangrove Action Project.