It’s back.

Grand Cayman’s coastline, from farthest east to the southwest, was awash in seaweed “mats” – known as Sargassum – following windy weather that hit the island in mid-June.

Department of Environment Deputy Director Tim Austin said the island’s western and northern coasts appear to have been largely spared in the latest weed invasion, prompted by southerly winds pushing it up from South America. Cayman saw similar influxes during the latter half of 2015 and 2016, although Sargassum seaweed’s “peak season” occurs in summer.

“The eastern Caribbean usually suffers worse than us, but we get our fair share,” Mr. Austin said. “There has just been more of it in recent years because of warmer ocean temperatures.”

Clean-up efforts were under way in some parts of the island this week, with most participants engaging in the back-breaking work of raking up the Sargassum or just picking it up by hand and shoving it into garbage bags.

Mr. Austin said the department is urging residents not to use heavy equipment to remove the seaweed from the beaches, partly because turtle nesting season is under way and partly because of the damage backhoes and bulldozers can cause.

“For every bucket of weed, you get half a bucket of sand,” he said.

If heavy equipment is needed, Mr. Austin said, the department asks that property owners consult with environmental officials before using it.

Although Sargassum can be unsightly, and smelly if it is left in the sun, Mr. Austin said it is often easier to let it lie on the beach for several days and “dry out,” making it lighter and easier to remove.

What is Sargassum?

Sargassum is a type of algae that floats in the ocean, typically after becoming dislodged from seabeds or coral – although two known species can reproduce without ever touching the sea floor.

The “Sargasso Sea” within the Atlantic Ocean gets its name from the weeds that grow there in abundance.

Mr. Austin said the summer months, which bring warmer ocean temperatures, will often cause a proliferation of the seaweed, and strong currents or high winds disperse it throughout the Americas and the Caribbean.

This is not an unusual event, he said. However, in recent years the amount of Sargassum floating in the Atlantic and eastern Caribbean, in particular, has increased markedly.

“It doesn’t always happen on this scale,” he said.

While Sargassum is problematic for residents and visitors who want to enjoy Cayman’s white sand beaches, the Department of Environment points out that it serves an important purpose as a nursery habitat for sea turtles and fish.

Such large deposits of coastline Sargassum were unheard of in the Caribbean before 2011, according to researchers who discussed the issue last year during an agriculture conference in Grand Cayman.

One researcher who spoke at the conference said the recent influxes of Sargassum across the Caribbean are likely to become “the new normal.”

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