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Green Tide

Mysterious matter threatens one of the world's most important ecosystems

By Rob Jordan 

Just as the sun was reaching its highest point in the sky, Lou Greenwell realized he could see again.

During a morning spent paddling across Blackwater Sound just off Key Largo, Greenwell, 70 years old, had begun to wonder if there was any end to the shadowy mass that stretched in every direction across the once-transparent waters. Then, in the shallows on the sound's far west side, little sand sharks appeared below the suddenly clear surface. Not-so-little barracudas rushed around Greenwell's banana-yellow kayak. One shark rested under a mangrove root, heedless of its visitors.

Greenwell was headed toward the Bogies, one of his favorite spots on earth. This narrow waterway has been a regular stop in the 40 years he's been swimming, fishing, diving, and kayaking the waters of Florida Bay. Forming a perfect canopy, massive, gnarled mangroves reached across the narrow passage as if longing for each other's embrace. Tiny warblers hopped from branch to branch, dancing between shadows and shafts of light. "You can get your prayer book out here," Greenwell said softly. "It's like a chapel."

It was in this chapel not long ago that Greenwell had a transformative experience. Leading a group of fellow kayakers in silence, he came upon something massive and still. With a swirl of water and mud, it became two massive things: a manatee and her baby, shyly making a delayed getaway. "It was the cutest thing," he said.

Looking at the water, Greenwell realized no such sighting would be possible now. The creeping pea-green cloudiness had made its way here, too. A hydrologist monitoring a nearby water quality station had warned that the Bogies were murkier than she had ever seen them. For a moment, Greenwell fell silent. The faint percussion of the highway — more than a mile away — echoed in the mangrove tunnel. "Yeah, the water is a little murky here," he said. Then, with hurt in his voice, he added, "This water is as murky as I've ever, ever seen it."

It is neither plant nor animal, yet it is alive.

It is about one-thousandth of the width of a human hair, yet, en masse, it's been known to block out sunlight for dozens of square miles. It has no external organs, yet can propel itself across oceans. It's the most ancient organism known, nearly as old as the oldest rock. About three billion years ago, it helped transform a toxic stew of methane, ammonia, and other gases into the oxygen-rich atmosphere we breathe. Now it's back, and it seems to have lost its good intentions.

Synechococcus elongatus is a kind of seaborne centaur. Like plants, it contains chlorophyll and can photosynthesize light. Like fish, it can regulate its own buoyancy, descending to the bay floor to collect nutrients and then rising again when sated. No one quite understands how the damn thing manages to swim around.

Oddly enough, this substance, referred to as "blue-green algae," is neither algae nor always blue-green. Scientists use the term because it is easily understood, but it's actually shorthand for a kind of unicellular phytoplankton (Latin for "wandering plant") that more closely resembles bacteria.

In the fall of 2005, the so-called algae crept into several small sounds in eastern Florida Bay where it had never been spotted before, quickly clouding waters that had previously been aquarium-clear. It killed off sponges and other bottom-dwelling sea life as it grew to cover an area more than three times the size of the city of Miami. More than a year later, the veil of green lingers, stretching from Everglades National Park, the largest subtropical wilderness in the United States, to Biscayne National Park, home to 10,000 years of human history. Tourism brochures touting an ecoparadise here now seem like the come-ons of a used car salesman. The unprecedented environmental attack and its unprecedented staying power have marine scientists scratching their heads, and fishermen crying into their beers.

Is this the beginning of the end for one of the world's most delicate and vital ecosystems?

The asphalt under Lou Greenwell's feet shook as he carried his kayak to the water. If he spat, he'd hit one of the tractor-trailers ripping by on this narrow strip of U.S. 1 between Key Largo and Florida City. On the other side of the road, backhoes and steamrollers smoothed the gravel bed that would soon be another lane of highway, another piece of asphalt to roll over on the way to Key West. With his back to the bulldozers, Greenwell shouted, "This is paradise for paddlers."

The concrete ramp at Mile Marker 111 is the only bayside public boat input for 18 miles. Two miles north, a formerly public ramp is walled off by concrete barriers. A neon-orange construction sign has the last word: "Notice: This boat ramp will close permanently in December 2006."

Greenwell, a retired airline executive, fights off arthritis with regular yoga classes and the multiday kayak trips he leads for the Paradise Paddlers, a local kayaking club. He's been fishing and diving in these waters since the Kennedy administration. When he retired eight years ago, he thought he'd get serious about golf. Then he discovered kayaking. "I haven't played a round of golf yet," he said.

With a singular smooth motion, Greenwell slipped into his fiberglass craft and floated out into the sound. The sun was brilliant, a few puffs of cloud decorated the horizon, and a warm breeze skittered across the water. But the water itself was almost unrecognizable — thick with pool-table-green ooze.

Greenwell didn't bother to unstrap his rusting fishing rod from the side of his kayak. There was nothing to see in the water, and no fish worth having would bother to stick around here. The sunlight-hogging algae had strangled the sea grass. There was little left for fish to feed on, and nowhere for them to hide.

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