Using Sargassum Beach/Dune Protection


Bill Sargent

Since March 23rd, Plum Island residents have watched contractors pump in five-football fields worth of sand several yards deep in front of Reservation Terrace.

It is hoped that waves and wind will shape the beach into nascent dunes planted with dune grass to hold them in place.

In Florida and the Caribbean, residents have been watching a blob of Sargassum weed the size of the United States floating toward their shores. When it makes landfall, the algae will rot and die, emitting a stench of rotten eggs. As a result, tourism has plunged 50% in some locations, fisheries have collapsed, power plants have clogged up, and the foul air has affected human health.

First, I would like to stick up for Sargassum weed.

Photo by Liz Yongue, Monroe County Extension Coordinator

If there were ever a keystone species, this would be it. Nothing is more beautiful and intriguing than diving under acre upon the golden-brown algae calmly drifting in the clear blue waters of the Southern Atlantic Ocean. This buoyant ecosystem harbors hundreds of species of crabs, shrimp, and fish, evolved specifically to live in this unique numinous habitat that puts Avatar to shame.

The problem is not Sargassum weed; it is what humans have done to change the environment of the Gulf of Mexico and the Atlantic Ocean. The Greenhouse Effect has warmed their waters, and agricultural runoff spewing out of the Mississippi River and southern rivers has over-fertilized their Sargassum pastures leading to runaway growth.

The media doesn’t point out that this massive blob of Sargassum weed also presents an easy, inexpensive way to remove almost a billion tons of oceanic carbon dioxide.

For years, places like Galveston, Texas, have used planes to monitor floating blobs of Sargassum weed. Then, when the Sargassum makes landfall, workers bulldoze it into dunes, where it fertilizes the dune grass. This works particularly efficiently because there are so few nutrients in a dune, so when you add fertilizer, the dune grass proliferates wildly.

If Galvestonians chopped up Sargassum weed, it could be used as a fertilizer like Milorganite made from the wastes of Milwaukee and Bostonite made from the scraps of Boston. Galvestonite or even Sargassumnite would work wonders on Plum Island’s new dunes.

Such projects make good small-scale operations, but the real payoff could be oceanic carbon dioxide sequestration. Nature has already done most of the hard work. It has grown thousands of acres of the oceanic crop, so we don’t have to produce it ourselves like kelp, and now it is being delivered to our shores for free.

All we have to do is bury it on land, or even better, pump it 450 feet below the ocean’s surface, where ambient pressure will crush its gas-filled floats so the fronds will drift down to the ocean floor and decompose in the cold bottom waters separated from the surface by warm water thermoclines.


Bill Sargent is a NOVA consultant and author of 28 award-winning books about science and the environment. His most recent book, BACKSTORY: Journalists Off the Record, is a novel that follows three journalists as they cover Covid, the Climate, and the War in Ukraine. It is available at local bookstores and can be ordered through Bill. In addition, he leads walks on Plum Island every Sunday at 10 AM.


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