Friday 22 November, 2019

What is sargassum seaweed threatening Caribbean coastlines?

Cayman is currently experiencing unprecedented sargassum blooms and because they are affecting watersports enthusiasts' and beachgoers’ enjoyment of some stretches of coastline, thus posing both environmental and tourism challenges, the Government is tackling the seaweed head on.

The seaweed is a naturally occurring phenomenon across the Caribbean but the situation is currently so serious in Cayman that the Government has established a task force to tackle it.

So what exactly is sargassum?

The Atlantic Ocean's Sargasso Sea was named after the algae, as it hosts a large amount of Sargassum. But the potent strain emanates from Brazil and it is dangerous.

Sargassum is a type of open ocean algae, brown in colour, that is only found in the Atlantic Ocean and provides refuge for migratory species. It is an essential habitat for several species of fish and invertebrates and provides shelter and food to sea turtles and commercially important fish such as Tuna.

Additionally, sargassum plays a role in beach nourishment, and is an important element in shoreline stability. But in excessive amounts, it may result in beach erosion and disruption in the aesthetic landscape. 

The proliferation of the seaweed is believed to be related to increased ocean temperatures and the availability of nutrients discharged from major rivers within the Caribbean Sea and Gulf of Mexico. The seaweed consolidates into large mats and is transported by ocean currents towards the Caribbean, washing up on beaches throughout the region.

As it collects and decomposes on the coastline, it produces an odour that attracts insects.

In some parts of the Caribbean, sargassum is used as animal feed, food for humans, in cosmetics, and in the manufacture of take-away containers for food and bricks for construction.

How can it be removed?

Raking and removal by hand is preferable to using heavy machinery on beaches, which can actually damage beaches because it removes sand and might cause coastal erosion during hurricane season. 

Turtle hatchlings also use sargassum as shelter, so clean-up crews should avoid sweeping away turtle tracks as they can be used to identify nesting sites.

Disposal:

- Stockpiling at a designated location, where the material should be turned occasionally to encourage its drying and the ultimate removal of sand

- All organic material should be disposed of at an appropriate off-site location and or burial on the beach where practical

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