Major influxes of dense mats of foul-smelling sargassum seaweed, like those that invaded Cayman’s beaches last summer, could be the “new normal” for the Caribbean, according to scientists and policymakers gathered in Cayman for a regional fisheries conference last week.
Unprecedented in the region before 2011, researchers are warning that such incursions could become commonplace and are advising governments to have management plans in place to react quickly.
Researchers are working on a study to help predict the movements of sargassum in the region’s waters to provide an advance warning system. A separate group was established at last week’s meeting to provide guidelines to the tourism industry and other authorities on how to handle the situation and manage the inevitable beach cleanups.
Some islands in the region saw major economic losses as a result of repeated, regular influxes of large swathes of the seaweed on pristine beaches and the situation is now considered a priority concern for tourism-based economies.
According to Hazel Oxenford, professor of marine ecology and fisheries at the University of West Indies, and one of the speakers at the Gulf and Caribbean Fisheries Institute conference at the Westin, Grand Cayman last week, a little sargassum is a good thing for coastal ecosystems.
Too much, however, can be disastrous.
“When it starts coming ashore in massive quantities and when it gets stuck in the near shore area and starts to give off that rotten egg smell, it becomes a real problem for tourism,” she said.
Until 2011, large influxes of sargassum were an unprecedented phenomenon in the Caribbean.
During that summer, beaches were closed in the eastern Caribbean and Mexico as the seaweed washed ashore day after day.
Beach managers, hoteliers and local authorities took heavy construction equipment onto beaches to remove the sargassum, which compounded the problem by causing significant beach erosion in some areas.
“We learned some hard lessons in 2011 that weren’t really shared. When it happened in the rest of the Caribbean in 2014 and 2015, they made the same mistakes,” said Ms. Oxenford.
Now, the University of the West Indies in collaboration with regional fisheries and environment groups, is issuing guidelines on how to manage future invasions.
“The most cost-effective and least environmentally damaging way to get rid of it is manual removal with rakes and wheelbarrows,” says Ms. Oxenford.
She said islands that rely on white sand beaches had naturally reacted by using what tools they had to get the seaweed off the beaches as quickly as possible.
“What they had was bulldozers. It is impossible to pick it up with bulldozers, without also picking up the sand. They scooped up a huge amount of beach which caused erosion,” she said.
Mobilizing large numbers of volunteers or buying new mechanical rakes is not without problems, however, and she acknowledges that individual islands will need to decide if the issue poses enough of a threat to warrant investment.
Cayman’s shape and location protect it from the worst impacts. The images of Seven Mile Beach swathed in dense mats of seaweed and the noxious smell of sargassum corralled in George Town harbor lingered for only a few weeks in 2015.
Other areas saw far worse impacts, with closed beaches and canceled vacations impacting fragile economies. Tobago declared the issue a natural disaster.
Ms. Oxenford said the research suggested that the problem was not about to go away.
“This is probably going to be the new normal,” she said. “It will vary between years because the sargassum bloom depends on factors like climate and water temperature. They accumulate in large gyres, then the water patterns and currents change, and they are released on to the beaches.”
She said such large sargassum blooms, typically seen in the Sargasso Sea around Bermuda, were new in the Equatorial region, potentially a product of warming ocean temperatures.
“Scientists are looking at these climate and ocean indices and what creates this perfect storm to allow us to predict when and where it will happen again.”