Until just a few years ago few people other than marine biologists and researchers had heard about sargassum, but when the invasive weed, originating from the mid-Atlantic Sargasso Sea, began devastating the shorelines of many Caribbean islands, scientists began taking a closer look. Policymakers too are now seeking ways to address what has become a recurring problem. 

Beginning in 2011, dense mats of foul-smelling sargassum weed have impacted marine resources, fisheries, waterways, shorelines and tourism.

The 2015 season was the worst on record, with 2016 and 2017 showing a slight downturn. Satellite imagery, new online tracking systems and reports from citizens, however, show that this year the Caribbean may once again have a serious problem with impact sargassum weed.

As the islands under the Miami based Caribbean Hotel and Tourism Association (CHTA) experienced a significant nuisance in 2015, the umbrella organization for 32 Caribbean countries issued a ‘resource guide for the Caribbean’ to inform the tourism industry, local governments, environmental groups and residents about sargassum weed, its impact and uses, and best practice mitigation and management measures which are being undertaken. In the meantime providing additional information about ongoing studies to further educate the tourism sector and other stakeholders.

The excessive growth of sargassum in 2018 seems grim. Researchers from the University of South Florida and NASA conclude that the past months showed the largest bloom in the central West Atlantic, as compared to the same months in past years. They suggest that the influx of sargassum in the Caribbean is due to pollution and a rise in water temperatures and low winds, which both affect ocean currents. In essence pieces of the sargassum are becoming entrained in currents which head towards the islands of the eastern Caribbean.

In the Sargasso Sea, the Mid-Atlantic ‘pool’ between four major Atlantic currents, about ten million tons of sargassum serves as an important habitat for many marine animals providing food, shade, and shelter from predators to fish, shrimps, crabs, and turtles. However, excessive amounts on beaches in populated areas can cause a lot of problems and the weed must be physically removed. Sargassum rotting on beaches smells bad, attracts insects, and causes many environmental problems, economic problems and possibly health problems. According to The US Occupational Safety and Health Administration of the United States Department of Labor exposure to hydrogen sulfide gas, which is given off as part of the natural decomposition of the rotting weed, can be a health risk.

Among the ABC islands, Bonaire’s windy southeastern coastline was first affected in early March, forcing hundreds of volunteers, forty military workers and several supporting organizations to undertake a massive cleanup of two species of brown algae: Sargassum Fluitans and Sargassum Natans.

Soon after, some of Curaçao’s bays and inlets on the exposed north coastline were affected. Alerted, NGOs, coordinated and supported by the government, joined forces. In Boca Patrick military workers placed a fence to collect the weed before it could reach the shore.

As it is expected that more weed will wash up in the coming years several companies are looking for new and faster cleaning methods than the current manual labor with pitchforks and rakes.

It might not be all bad.

Sargassum may serve as fertilizers for sand dunes and thus protects shoreline stability. It is also a marine resource for other uses such as organic mulch, biomass for food, fuel, and as a possible source of pharmaceutical materials.

An application to predict and monitor the track of the sargassum masses was developed at the University of South Florida. An internet site with satellite imagery of sargassum, resulting in an online ‘Sargassum Watch System (SaWS) allows countries in the impact areas time to prepare.  The site distributes information and daily images with surface currents, allowing viewers and researchers visually estimate sargassum aggregation and movement directions.

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