Sargasso's Seaweed Trek to the Caribbean.

(Dive Travel Business News - October 17, 2011) -- Since June the Eastern Caribbean has been invaded by an extraordinary volume of seaweed, sending resorts and government agencies, from Anguilla in the north to Tobago in the south, scrambling to rid beaches of the smelly, brown, bug-attracting algae before the impending high season.

While small amounts of Sargassum are normally found in the Caribbean from May to September when regional currents and winds transport the floating algae to the islands, such large accumulations across so many regions have never before been recorded.  

So much Sargassum seaweed has been washing up on Eastern Caribbean beaches this summer and fall that St. James's Club & Villas in Antigua was forced to close for several weeks in September where the weed, a floating species of algae that inhabits the Sargasso Sea, had completely filled the bay on which the hotel sits, leaving piles as high as five feet tall along the usually pristine shore. 

Rob Barrett, chairman of Elite Island Resorts, which includes the St. James’s Club, said that it took three backhoes and five 10-ton dump trucks hauling seaweed “12 hours a day, 7 days a week for 3 weeks” to clear the beach, which he said is now cleaned up. The effort, combined with the loss of guests during the closure, cost the company about $1 million. Beaches on Antigua's northeast and southeast coasts were also affected. 

In St. Maarten, swimmers were warned away from some beaches because of fears that they could get tangled in the seaweed and drown. In Anguilla, removal efforts have been under way for weeks with private contractors being hired to remove the piles of weed, along with business operators on the beach, and supplemented  by local volunteers.

In Barbados, the government installed an oil-containment boom across the mouth of a river on its northeast shore to keep the weed at bay. In Tobago, where for several months workers have been carting the stuff off beaches regularly and trucking it to the dump, the government has been encouraging farmers to use it as fertilizer.

“This is completely unprecedented,” said David Freestone, executive director of the Sargasso Sea Alliance in Washington, D.C., which has been fielding reports of unusual quantities of the seaweed washing ashore in places as far-flung as Sierra Leone in West Africa. It appears that the seaweed invasion was caused by a rare combination of storms and currents which carried weed from the Sargasso Sea to the Caribbean. Theories as to why range from climate change to the Gulf oil spill. But at least for now, “it’s a mystery,” Mr. Freestone said. 

Seaweed plays an important role in the Caribbean ecosystem, and such large quantities can have positive and negative effects. Sargassum can help bulk up eroding beaches, for example. But large deposits can also make it difficult for tiny sea turtle hatchlings to find their way to the ocean. It also serves as fertilizer on beaches and it may turn out to be extremely positive for fishery resources because the seaweed becomes a refuge and a food source for young fish and other sea creatures.

The Sargasso Sea is a region in the middle of the North Atlantic Ocean 700 miles wide and 2,000 miles long that is surrounded by ocean currents. It is the only "Sea" without shores and is bounded on the west by the Gulf Stream, on the north by the North Atlantic Current, on the east by the Canary Current; and on the south, by the North Atlantic Equatorial current: This system of currents forms the "North Atlantic Subtropical Gyre".  All the currents deposit the marine plants and garbage they carry into this sea.

The Sargasso Sea is named for Sargassum, the holopelagic, brown drift algae that can aggregate to form extensive floating mats on the surface of the ocean. Dr. Sylvia Earle has called it "the golden rainforest of the ocean." The Sargassum seaweed typically stays in the Sargasso Sea, but cyclical currents this year pushed vast quantities of the seaweed into the eastern Caribbean. The Sargasso Sea is a haven of biodiversity and there is growing recognition of the crucial role it plays in the wider North Atlantic ecosystem as habitat, foraging and spawning grounds, and as a migratory corridor.

The Sargassum is not a threat to shipping, and historic incidents of sailing ships being trapped there are due to the often becalming winds of the horse latitudes.  This floating mass of  seaweed plays a major role in the migration of the European Eel and the American Eel. The larvae of both species hatch there and go to Europe or the East Coast of North America. Later in life, they try to return to the Sargasso Sea to lay eggs. It is also believed that after hatching, young Loggerhead Sea Turtles use currents, such as the Gulf Stream to travel to the Sargasso Sea, where they use the Sargassum as cover from predation until they are mature.

At this point, the Sargassum weed problem in the Eastern Caribbean appears to be abating. Cooler fall weather traditionally slows algae’s growth, changes ocean circulation patterns, water temperature and nutrient systems. These shifts typically keep the weed at sea. 

The big unknown is what might happen next year. “The question of whether it was an exception to the rule or representing some sort of regime shift in the way ocean currents are operating is a pretty major question,” said Jeff Ardron, director of the High Seas Program for the Marine Conservation Institute in Washington, who has been tracking the issue. A repeat, he said, could “strongly indicate that something serious is afoot.”

Credits:
American Museum of Natural History Milstein Hall of Ocean Life
http://www.amnh.org/exhibitions/permanent/ocean/01_dioramas/e_sargasso.php
http://en.wikipedia.org/wiki/Sargasso_Sea
http://travel.nytimes.com/2011/10/16/travel/caribbean-beaches-dig-out-fr...

** This RSS Feed is brought to you by www.DiveTravelBusinessNews.com **