Mysterious masses of seaweed assault Caribbean islands

In retrospect, 2011 was just the first wave. That year, massive rafts of Sargassum—a brown seaweed that lives in the open ocean—washed up on beaches across the Caribbean, trapping sea turtles and filling the air with the stench of rotting eggs. “It presented immense challenges,” says Hazel Oxenford, a fisheries biologist at The University of the West Indies in Cave Hill, Barbados. Before then, beachgoers had sometimes noticed “little drifty bits on the tideline,” but the 2011 deluge of seaweed was unprecedented, she says, piling up meters thick in places. “We’d never seen it before.”

Locals hoped the episode, a blow to tourism and fisheries, was a one-off. But a few years later “it came back worse,” Oxenford says. Now, the Caribbean is bracing for what could be the mother of all seaweed invasions, with satellite observations warning of record-setting Sargassum blooms and seaweed already swamping beaches. Jim Gower, a remote-sensing expert with Fisheries and Oceans Canada who is based in Sidney, British Columbia, and his colleagues looked for spots on the ocean’s surface that reflected unusual amounts of near-infrared light, a part of the spectrum that plants don’t harvest. Data from May 2011 showed a huge patch of floating plants, presumably Sargassum, off the coast of Brazil—far to the south of its normal habitat. By September, it stretched from the Caribbean all the way to the coast of Africa, the team reported in 2013.

To confirm that the Sargassum fouling Caribbean beaches in 2011 came from the tropical Atlantic, east of Brazil, Franks and his colleagues traced the likely path of seaweed masses backward through time. First, they compiled records of locations where Sargassum came ashore. Then, using information about surface currents, they calculated its likely source. “Invariably, in all of those instances, it tracked back to the [tropical] region,” says Franks, who reported the findings in 2016. “None of it ever tracked northward into the Sargasso Sea.”

Click here to read the rest of the article in Science Magazine

Masses Of Seaweed Threaten Fisheries And Foul Beaches

If you've been to a beach this summer, anywhere from Texas to the Carolinas, you've likely seen it. Masses of brown seaweed, sometimes a few clumps, often big mounds, line the shore. It's sargassum, a floating weed that's clogging bays and piling up on beaches in the Gulf and Caribbean.

In Barbados, Hazel Oxenford says sargassum is more than a headache, it's a national emergency. Oxenford, a fisheries biologist at the University of the West Indies, says the seaweed piles up on the shoreline there 10 to 12 feet high. Even worse, she says, masses of the weed cover the water near the beaches.

"It creates tremendous problems for the natural ecosystems," she says. "We've had significant loss of endangered sea turtles that have actually drowned because they can't get to the surface because the sargassum above them is so high."

When large mats first appeared in the Caribbean, many thought it was from the Sargasso Sea, an area in the Atlantic north of the Caribbean. But Franks and other researchers traced the seaweed to a massive bloom that has appeared off the coast of Brazil. Ocean currents carry the seaweed up the South American coast into the Caribbean, where Franks says the impact on fisheries has been catastrophic.

Click here to read the rest of the article in NPR

Here is a podcast about Sargassum on "All Things Considered" on NPR

Mexican Caribbean sees sargassum barriers placed from Cancun to Chetumal

After a delay, the first sargassum barriers have been placed in the sea which will eventually run from Cancun to Chetumal.

The Secretary of Ecology and Environment of Quintana Roo, Alfredo Arellano Guillermo, says the government has begun working with the Chetumal company Goimar Logistics and Services with seaweed barrier placements in the sea.

“The project consists of the installation of a system of containment barriers that will be placed along 27 kilometers of the state coast from Cancún, head of the municipality of Benito Juárez in the north, to Chetumal Bay, head of the municipality of Othón Pompeyo Blanco to the south,” he said.

According to the development company, the containment line integrates tools used for the containment of oil spills and have been developed for the management of sargassum. The barrier is non-polluting and resistant to waves and is supported with seabed anchoring.

Once in place, the barriers will redirect the collected sargassum away from the coast. The company says the barriers are a technique for the control of natural and artificial marine contingencies. They are composed of a flotation system and polyvinyl coated canvas barrier with additives for ultraviolet ray resistance.

Once completely installed, 27 kilometers of barriers will float along the coast which will prevent a large majority of the seaweed from reaching the beaches. This project is the first one coordinated by a state government which in part, has resulted after numerous tourist complaints about the seaweed along the Yucatan coast.

The installation of the barrier system will include the municipalities of Othon P. Blanco, Benito Juárez, Solidaridad, Puerto Morelos and Tulum.

Riviera Maya

Minister Heredia speaks on sargassum

With the recent issues involving the overgrowth of sargassum along Belize’s coastline, many communities have been doing everything possible to not only clean, but to minimize the amounts accumulated on the seashores. Various communities such as San Pedro, Caye Caulker, Hopkins and Placencia are all battling with the seemingly never-ending incease of sargassum on their beaches. Minister of Tourism, Manuel Heredia Jr, and inhabitant of San Pedro, spoke on the issue.

Manuel Heredia Jr. Minister of Tourism and Civil Aviation: “We have a task force made up of DOE, Coastal Zone, Fisheries Department and our own people form the industry as to what will be the short term, middle term and long term for this one because we have seen rather than minimizing it; it is increasing. The amount that we are getting in the Belizean Coast Line is much greater than anytime in my 30 years of fishing that I did. I have never seen anything like that. It used to be three months now we cannot say how long it will last. It was predicted by scientist that it will finalize in the middle of August . We are now in September and we are seeing it rather than diminishing it is increasing so I had a visit to Placencia on Wednesday and I stopped by also at Hopkins to see.

He, however, states how pleased he is to see everyone working together and the plans that are in store to minimize the current problem.

Manuel Heredia Jr. Minister of Tourism and Civil Aviation: “I am glad of the initiative that stakeholders and the villagers are taking in Placencia. The second step to that is putting these curtains to protect. It will not be to stop it but to protect it before it reaches the beach so they are working on that and they will advise us and so on when they have all the information together. Like in San Pedro, Gran Caribe started with that already but it needs to be a team effort that all hotels will do to divert it and eventually it can go to an area where it doesn’t affect the industry.”


Working with Southern Enviromental Association (SEA) last week at Gladden Spit and Silk Cayes Marine Reserve, we came upon a huge field of sargassum. You can gauge the size by our boat in the lower left. What you see is about 1/4 of the total field even though the drone was at maximum height of 1600ft.

Photo and text by Tony Rath