Damaging algae worries scientists

One analysis at least partly blames work on U.S. 1 for the blue-green bloom north of the Keys.

Published August 19, 2006

KEY LARGO - Lain Goodwin eased his boat into Florida Bay, hoping for the water to clear. He looked for the holes in the bay floor where he would always catch some snook, but there was nothing to see. The only clear blue was the sky.

Back east across Blackwater Sound, under the construction along U.S. 1, through Barnes Sound and 5 miles north into Biscayne Bay, the water remained the same deep green as the mangrove stands that hug the islands of the upper Florida Keys.

The shallow waters from Key Largo north to Arsenicker Keys have been clouded by a blue-green algae bloom spreading across 175 square miles of Florida and Biscayne bays since autumn. It stretches into parts of Everglades and Biscayne national parks, threatening the fragile seagrass that supports the state's fishing industry, conservationists say.

"I just don't see an end to it," Goodwin said Thursday aboard his 22-foot fishing boat, idling in the calm yet murky waters off Homestead.

Disturbances from last year's hurricanes likely stirred up phosphorus in the water, feeding the algae, but construction widening an 18-mile stretch of U.S. 1 between Florida City and Key Largo may also be to blame, according to a South Florida Water Management District analysis.

"An interaction of these two factors ... appears to be the likely cause of the blooms," the report states.

The road widening and bridge construction began in April 2005 after a federal judge denied an attempt by environmental groups to block it. The $268-million project is scheduled for completion by June 2009.

Florida Transportation Department officials dispute the water management district's analysis.

"If construction did contribute, I would think it would be very little. I think nature is the biggest culprit," John Martinez, a district secretary, said Friday.

The algae is concentrated near the road construction in waters where such a bloom has never been recorded, according to the water management district report.

"It's where the water looks the worst, and it's persistently in place around this road construction," said Peter Frezza, research coordinator at Audubon of Florida's Tavernier Science Center.

Audubon is studying the effects of water quality on seagrass, fish and birds in Florida Bay. Frezza said current light penetration readings in the bay are the dimmest on record.

Storm surge alone could have disrupted the sediment and released excess nutrients into the water, Frezza said, "but here's the problem: We're almost a year off that hurricane season and this bloom has not subsided at all. If anything, it's getting worse."

Seagrass holds down sediment in the shallow bay waters, but needs sunlight to thrive. The algae bloom, though nontoxic, blocks the light.

"If we start having mass seagrass fatality, it could be a disaster for the Florida Bay. That's the bottom of the food chain, everything is based on seagrass - from the tiny little bacteria and the small crustaceans that eat them, and it goes all the way up to the largest fish," Frezza said.

Goodwin and other boat captains say the bloom has disrupted their fishing charters out of Key Largo.

Goodwin takes nearly all his charters into eastern Florida Bay and the southern end of Biscayne Bay. "Normally it looks like an aquarium," he said. "The fishing, it's been dead."

He spends an extra $10 to $30 a day on gas for his boat now, trying to find clear water, he said.

Seagrass beds farther west in Florida Bay still have not completely recovered from an algae bloom more than a decade ago, Frezza said. Negligent boaters also have cut wide swaths across seagrass beds in the bay, destroying fish habitat.

"It could probably become a really dirty basin, and realistically we could never see seagrass in the bay again," Frezza said.