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.
A few more dips and swerves and we enter Pumpkin Bay, which sparkles in the early afternoon sun. Doyle points to a nearby cluster of mangroves, perhaps a half-acre in size. One summer evening in 2000 he made a startling discovery: This unnamed island, barely the size of a suburban house lot, was an enormous roost for wading birds. He returned every month to take a census. It was always a beautiful sight: the fading sun burnishing the island, the birds shining, he says, "like Christmas tree ornaments.'' That August he could barely put down his binoculars for an hour. "It's overwhelming,'' Doyle says. "There's so much going on.''
When Doyle did finally rest, the tally was 10,224 birds--including more than 7,000 white ibises. The count from the tiny island was enough for Doyle to nominate the refuge as an Important Bird Area.
"Nobody knew about that,'' he says, "and nobody would unless they were out in the middle of the Ten Thousand Islands at sunset.''
The flocks have since moved on. While the isle is a refuge from predators, Doyle believes Pumpkin Bay's changing hydrology prompted many of the species to seek fresher water. Owing to ill-considered engineering projects like the Highway 41 causeway, failed real estate schemes, and a grid of drainage canals, the lower Everglades has been thirsting for freshwater. Without this constant flow, formerly brackish bays have become hypersaline; some freshwater marshes have been lost altogether.
Since the Comprehensive Everglades Restoration Plan was approved in 2000, a massive rescue operation has been under way throughout south Florida; canals were dammed and filled, and culverts were installed under Highway 41 to promote a greater "sheet flow" of water. This is one of the reasons we're out here now, taking readings from water level and salinity recorders installed throughout the refuge's various habitats by the USGS to gauge what would result from extensive replumbing efforts (see "Think Pink," opposite). Somehow Doyle locates the Pumpkin River channel through a bulwark of foliage and we wind our way upriver. The red mangroves all look identical, but Doyle noses the skiff's bow into the confusion. We've nearly arrived at the Mangrove West site. Dead reckoning? Try GPS.
Limbs lash at us as we clamber from the boat and gingerly hop from prop root to prop root for 50 feet until we reach the muddy mainland. Here, on semisolid ground, the trees are primarily black mangroves; the rising tide has already covered their roots, leaving only thousands of spiky pneumatophores peeking above the murky surface. The forest has opened up as well, with numerous cylindrical breaks in the canopy caused by lightning strikes.
Doyle uses a syringe to draw out water samples from various soil depths to measure salinity levels, while From downloads data and changes AA batteries on a water-level recorder. Somewhere in the woods a red-bellied woodpecker knocks out a rat-a-tat beat on a hardwood.
We repeat the routine at three more stations, including Ecotone East, a messy, muddy, quarter-mile slog from the manmade Faka Union Canal through red and black mangroves and a chest-deep slough to a marsh being swallowed by white mangroves. On our return down the waterway, we spot several manatees and a breaching spotted eagle ray. Out in the islands again, garlands of oysters gleam like a jeweler's showcase upon the red mangrove buttresses. Above the canopy an osprey tears into a freshly caught mullet. The tableau is at once raw and beautiful, but I can't stop thinking about the Swiss cheese holes drilled in the mangrove-forest canopy by lightning strikes. I ask From about evasive action in the event of an electrical storm, a common occurrence this time of year.
"Beach the boat and get as far into the mangroves as possible,'' he advises. "Pray it's not an all-day affair. And you do not want to be out in an airboat,'' referring to the craft's metal frame, which can function nicely as a lightning rod.
Naturally, the following morning we launch the refuge's airboat at the end of a one-mile track south of Highway 41. At least the rising sun, brass-brilliant as a freshly minted penny, portends a clear day. The distinctive Florida watercraft--basically a flat-bottomed launch powered by an aircraft engine--offers the best access to the eight recording stations arranged throughout wetlands that are too shallow for the skiff yet too mucky for any four-wheel-drive vehicle. We adjust sound-deadening earmuffs, and Doyle revs up the prop. Soon we're hurtling along an inches-deep channel flanked by red mangroves.
Everywhere there is a tidal waterway--bay, estuary, river, canal--within the refuge, chances are red mangroves have a foothold. In yet another ingenious adaptation, the species produces dagger-shaped seedlings that germinate while still attached to the trees; after dropping off, they can survive for months in saltwater before settling into an ooze of land or a drainage ditch. These new recruits are precocious, growing two feet their first year, producing prop roots within three, creating robust stands within a decade.