Sargassum seaweed build-up much thicker than usual this summer in the Keys

kwadlow@keynoter.comJune 25, 2014 

The shoreline of Sombrero Beach in Marathon is covered in sargassum. Presumably, the city will remove it before the annual Fourth of July party and fireworks at the beach.


Sure it smells, but the summer arrival of sargassum seaweed reaching the Florida Keys does a lot of good.

"There is all kinds of good stuff in that rackline for shorebirds to feed on," said Jerry Lorenz from Florida Audubon's Tavernier Science Center.

"One of the big environmental problems we have in Florida is that everybody rakes seaweed off their beaches," Lorenz said. "It's really good for wildlife. A lot of little brown birds rely on it."

Reports of high levels of sargassum seaweed build-up this summer range from the Gulf of Mexico coast in Texas to Caribbean islands like Trinidad and Tobago. Sargassum weed also has covered the oceanfront at Marathon's Sombrero Beach and built up at Harry Harris Park's boat ramp in Tavernier.

Key West keeps its beaches relatively clean with a contractor removing seaweed daily, so the accumulation is less noticeable, city spokeswoman Alyson Crean said.

"There is one area the contractors can't get into, at the end of Smathers Beach near the airport," Crean said. "You could smell it over the weekend but I didn't notice anything" Tuesday, she said. "It seems to work its way back out of there eventually."

Lorenz said he saw seaweed piling up on Anne's Beach in Islamorada recently "but I've seen it that thick there before."

Islamorada Public Works Director John Sutter said Anne's Beach usually does not have serious seaweed problem since the large oceanside flat there tends to funnel floating vegetation beneath the Channel 2 Bridge.

The Founders Park beach, on the bayside, seldom has a troublesome seaweed buildup, he said.

"It's pretty typical to get sargassum this time of year, when it's pushed in the by prevailing southeast wind," Sutter said. "It's smelly and it gets trapped in some docks and seawalls, but it does degrade."

Islamorada charter captain Steve Leopold said the weedlines offshore were thicker in early June than they were this week.

"It was bad, but not that extraordinary," Leopold said. "It made trolling more difficult, but the weed is good for the fish. It brings them food and gives them a place to hide."

Officials in Galveston told the Houston Chronicle that large mounds of sargassum on tourist beaches have required around-the-clock cleaning.

A Texas A&M University seaweed expert told the Chronicle "this year is the biggest onslaught of seaweed he has seen since beginning research in 2003."

Sargassum seaweed comes from the North Atlantic area called the Sargasso Sea. In the summer, currents and wind conditions cause the growth to break free and drift through the Caribbean and into the Gulf of Mexico. 

"It stops when the winds change in the fall," Sutter said.

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