Clumps of seaweed the size of hay bales are undulating in Gulf waters and washing ashore from Fort Myers to Anna Maria Island.
A 3-foot-wide mat of seaweed stretched for miles Thursday along Manasota Key as beachgoers wrinkled their noses at the rotting smell.
On Siesta Key in Sarasota, county beach managers have already spent more than $130,000 to dispose of more than 2,200 tons of unsightly seaweed since October.
This is just the beginning of the season when red seaweed usually starts to proliferate, said Brian LaPointe, a marine biologist hired by the state to study nuisance seaweed in the Gulf.
And it looks like more seaweed is on the way because of dry weather and the accumulation of nutrients on the ocean floor, LaPointe said.
The seaweed is a type of algae commonly referred to as red drift. It looks like tangled mats of hair on the beach and is more a nuisance than a health threat.
Unlike red tide, a microscopic algae that kills sea life, red drift produces no toxins.
Swimming in it, however, can cause rashes in some people.
"It needs to be in the trash can," said Charles W. Gross, a Rotonda resident who was fishing on Englewood Beach on Thursday.
LaPointe has been studying red drift algae on the Gulf coast ever since a particularly bad bloom in 2004 dumped piles of the smelly stuff knee-deep onto Fort Myers beaches.
This years' bloom could rival that of 2004, LaPointe said. He said he has never seen a documented case of more red drift algae in the Gulf.
The algae attaches to rocks, coral and the shells of worms that live in the sediment. Waves rip the algae from its foothold and send it drifting until it dies and sinks or washes ashore. Red drift algae normally starts to grow when the Gulf waters turn crystal clear in the dry season and they begin to really take off after the first spring rain, LaPointe said.
By the fall, when the water is more murky, the seaweed tends to subside.
This year it did not, LaPointe said.
He expects the problem to become worse in areas where red tide hit hard in 2005.
After red tide killed off thousands of fish that year, the fish sank to the sea floor and began to decay. The decay robbed the water of oxygen and created a 2,000-acre dead zone from Sarasota to Tampa Bay. Dead matter rotted into nutrients that LaPointe said are still at the bottom of the Gulf.
The red drift algae taps those nutrients to grow. Nutrients also accumulate in the Gulf from the air and from rivers such as the Caloosahatchee and the Peace, which carry land-based nitrogen and phosphorus, LaPointe said.
"What we're seeing is nutrients building up in the sediments from these past several years," LaPointe said.
Wayne Genthner, a boat captain who runs daily charters out of Sarasota Bay, said red drift algae has been floating about a half mile to two miles offshore of Coquina Beach for a few months, but in the past couple weeks it has grown worse.
On Thursday, he compared the globs of algae to hay bales and said he mistook one clump for a large sea turtle.
"When you've got balls of algae the size of sea turtles floating around out there, there's something wrong with that," Genthner said.
