By Michael Jarvis, London UK
From Cayman to Cancun and affecting beaches in the eastern and western Caribbean all the way to the Sargasso Sea in the vicinity of Bermuda (hence the name), sargassum seaweed is a nightmare for the tourism-dependent countries on whose shores it despoils.
And it’s happening again.
Acres of the floating brown mass of matted seaweed are once again drifting on the waves carried by currents and plaguing beaches across the region.
Scientists attribute the origins of ‘pelagic sargassum’ in part to the warming of the ocean caused by climate change, and manmade causes. Factors include the discharge of macronutrients from agricultural run-off and wastewater via major river basins such as the Congo and Amazon Rivers, and the deposition of iron and nutrient-rich Saharan dust on the ocean.
Experts monitoring the movement of sargassum in the region report that in recent years the size of the floating mass had grown into the largest ever recorded measuring over 5,500 miles extending from the central Atlantic and the Caribbean Sea to West Africa and the Gulf of Mexico.
It's predicted that 2021 could be a particularly challenging year.
Satellite monitoring reports from NASA and the University of South Florida indicate that the floating sargassum bloom has shown accelerated growth since December.
Meanwhile, the suspected causes of this sargassum surge - including deforestation and increased fertilizer use in the Amazon region, along with climate change - are continuing unabated.
With sargassum blooms at their largest in June and July, already a recent growth covering an area measuring 33 square miles, landfall is already being recorded along several coastlines.
According to maritime experts, the dynamics of the sea currents and the trajectory that the floating mats have followed in previous years indicate that the sargassum is likely to travel westward through the Caribbean region until it meets the Mexican coasts, where it circles back and heads to south Florida and out into the Atlantic.
The sargassum landfall is characterised by its foul odour, dead marine fauna and tons of accumulated algae on the coast choking up beaches.
Despite its pungent smell and unsightly appearance on shore, when it’s in the open sea sargassum serves as an important breeding ground for turtle hatchlings and a refuge for hundreds of fish species.
But the revolting smell is a challenge for the tourism industry which relies on beaches as a key attraction. The cost of clearing the debris and public health concerns due to insects attracted by the rotting material.
There have been some attempts to harvest the sargassum and converting it to fertiliser (Barbados), turning it into soap (Mexico), and animal feed and as a biofuel (Jamaica).
As Antigua and Barbuda's Minister of Environment, Molwyn Joseph, has stated: “We have made the assumption that this is going to be an annual thing, and the same way we prepare for hurricanes we have to prepare for Sargassum.”