Sargassum in Saint Martin

After being away for a couple weeks, I returned to find the sargassum that had been washing up on the beaches of St. Martin has accumulated to a surprising degree. Sargassum is seaweed, and typically refers to a couple species in the genus Sargassum that live in the open ocean. This is unlike many macroalgae, which are attached to the bottom in shallow waters.

The Sargasso Sea in the North Atlantic Ocean is, of course, named after this alga. For the most part, currents surrounding the Sargasso Sea keep the sargassum in that area. The seaweed provides food and cover for certain marine animals, such as the loggerhead sea turtle.

At this point, I don’t know that there is a definitive answer about why such a large amount of sargassum is showing up in the Caribbean this summer. Some have noted that there are higher than average temperatures in the North Atlantic, which may have increased the amount of sargassum.

On St. Martin, primarily the Atlantic-facing eastern beaches have been impacted. In Grand Case, for example, one would have no idea that anything unusual was going on. Below are some photos from the beach at Grandes Cayes, where there are some pretty significant accumulations. When decomposing, the hydrogen sulfate that is released smells unpleasant and may pose some threat to those with asthma or other respiratory conditions.

What’s next? It’s tough to say. Removal from the beach is difficult without also removing sand, and heavy equipment would likely destroy sea turtle nests. As long as it stops accumulating, which seems likely, then it should biodegrade naturally over time. In the meantime, it’s a boon to isopods and other beach denizens that can eat it.

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