Sargassum Seaweed Turns the Caribbean's Crystalline Waters Murky

Sargassum lines a Caribbean beach in 2011. photo by Mark Yokoyama; used under a CC BY-NC-ND 2.0 license.

Sargassum lines a Caribbean beach in 2011. Photo by Mark Yokoyama. Used under a CC BY-NC-ND 2.0 license.

Say the word “sargasso” and West Indian literature fans will automatically think of the critically acclaimed novel by Dominican-born British writer Jean Rhys, “Wide Sargasso Sea“. But now, sargasso — or as many are calling it, sargassum — the elegant-looking, dark brown seaweed with tiny berries, has been washing up in bulk along shores from the southern United States to the Caribbean.

The presence of the algae in regional waters is nothing new. In fact, there is an entire area in the northern Atlantic Ocean named for it. But the sheer volume of sargassum over the last month or so is concerning; some are attributing the phenomenon to climate change.

Naturally, Caribbean governments are concerned about the effect of the seaweed on tourism. Sargassum along Tobago's eastern coast was piled so high on the beaches that some of it had to be removed with the help of backhoes. Guests at one upscale hotel on the south-east coast of the island complained that the smell from such large quantities of the algae was nauseating. Still, as of last week, Tobago seemed to be full of holiday-makers, as the island's western coast remained unaffected, likely due to the motion of the tides.

One PADI-certified diver, Dave Elliot, who regularly dives in Tobago, filmed a short video about the sargassum — first, viewers get a perspective from the shoreline, and then from underwater. It's fascinating and well worth a look.

In the first part of the video, the entire stretch of Tyrell's Bay in Speyside, on the island's north-east coast, is thick with sargassum to the point where the water actually looks like mud. At about 5:45 in the timeline, the divers go directly underneath the sargassum. The closer to shore they reach, the darker it becomes; they soon have to turn on their lights in order to get any visuals on the camera and they must use their compasses to tell which direction they are going. The algae was so dense that it made swimming quite challenging. Elliot narrates:

Occasionally, maybe as a wave would roll, the light would peer through from the top […] Meanwhile, on the sea floor, the area is very sandy. What was noticeable was the absence of the normal algae-eating fish that we know: the parrotfish, the angelfish, the surgeonfish, trumpetfish and all the other smaller versions…the damselfish and such like…there were no signs of these species of fish.

Elliot soon discovered that the entire sea floor was “carpeted with the weed”; he did not notice “much life underneath there”. This has been one concerns of environmentalists — that the abundance of seaweed could be affecting marine life — though in a newspaper column, Lori Lee Lum, the community education officer at Trinidad and Tobago's Institute of Marine Affairs noted:

Besides being a food source, this seaweed community supports a diverse ecosystem and provides critical habitat for a wide variety of sea life including crabs, shrimp, molluscs, fish such as mahi mahi, and sea turtles, and is a nursery and spawning area for others.

Elliot and his diving companion soon had no choice but to find their way back to the jetty at Blue Waters Inn on the northeastern part of the island; the underwater images are murky; almost eerie. Tobago's fishermen have been adversely affected as well.

Interestingly, four years ago in September 2011, when the region also experienced an influx of sargassum, an octogenarian entrepreneur from Barbados found a way to turn the sargassum problem into profit. The Barbados Government Information Service produced a video feature on the process Cavendish Atwell uses to make a sargassum-based fertiliser:


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