An old weed becomes a modern problem

The so-called “Sargasso Sea” in the North Atlantic Ocean is a time-honored name, dating back to well before Christopher Columbus’ day.  It may have been known as early as the sixth century BC, according to one ancient navigator‘s oral history.  The map below is courtesy of Wikipedia.

Its name was derived from the sargassum seaweed that proliferates there.  In more recent times, the Sargasso Sea has become the heart of the so-called North Atlantic Garbage Patch.

Now it looks as if sargassum is spreading south, into equatorial regions, and posing a new and highly unwelcome threat to the tourist industry in South America, the Caribbean, and even Florida.

Stretching up to 5,500 miles (8,850 kilometers) from the Gulf of Mexico to just off the coast of western Africa, the Great Atlantic Sargassum Belt appears to be the product of natural and human-caused factors.

. . .

[Researchers] identified a tipping point around 2009 when discharge from the Amazon River brought unusually high levels of nutrients into the Atlantic Ocean. Upwelling of nutrient-rich water off the west coast of Africa in the winter of 2010 further enriched surface waters with deep-sea nutrients; that upwelling also lowered temperatures of that surface water, allowing sargassum to thrive in the summer of 2011 … The largest recorded bloom occurred in 2018, when the Great Atlantic Sargassum Belt grew to a mass of more than 20 million metric tons.

. . .

“As sargassum decays it consumes the oxygen, creating low oxygen conditions, which is not a good condition for marine life in a coastal ecosystem,” Wang said. Coral reefs and seagrass ecosystems can suffer when high levels of sargassum change water chemistry and block organisms from moving freely.

“Sea turtles sometimes can’t swim through the dense mats to return to open water after laying their eggs,” she said.

The Great Atlantic Sargassum Belt is also having an effect on coastal tourism … In addition to disrupting coastal ecosystems, decaying sargassum releases hydrogen sulfide, a potentially harmful gas that smells like rotten eggs.

There’s more at the link.

Here’s a video report showing the extent of the problem for the tourism industry.

It seems to me that recyclers are ignoring a potentially useful resource here – one that tourist centers might actually pay them to take away.  Sargassum, like other seaweeds, is often used as fertilizer in other parts of the world.  Why can’t it be collected and used the same way in nearby areas?  There are many other economic uses for seaweed;  follow those four links for more information.  Why not take advantage of those markets to dispose of a problem?



  1. We gets lots of it here on the GOM coast. It is too salty for most plants. Every time I tried it killed whatever I was using it under. Washing it is time intensive and generally seemed to fail for me. Waiting for it to naturally leech out its salt content seemed to miss the useful stage of decomposition too. If someone finds a good method, there is no shortage of the raw material.

  2. Wow, they just now discovered that Florida East Coast beaches get covered by sargasso weed?

    I could have told them this in 1973. The weed’s always been found heavily on the beaches during winter or after storms.

    I think this is more Globul Warming hookum.

  3. What Beans said, except being older, I could have told them about sargasso on south Florida beaches in the mid 60s. It’s also vital ecosystem offshore. Fishermen search for weed lines because they attract small fish for shelter, which attracts big fish for the buffet.

    I’d be concerned if there wasn’t sargasso on the beaches.

  4. What SiG said, if you want to really snag some Dorado/Mahi-mahi/Dolphin fish, troll along the edge of the weed line. The really big monsters will hide under the edge, waiting for bait to dash to the supposed protection. Bam! Get you a 3-4 footer and it will work you to death on light tackle, if you keep it. Heck, a 4 footer will work you to death on heavy tackle using a chair or fighting rig.

    What the ‘My Head’s on Fire’ people don’t get is it is a bad thing when the high-water mark isn’t covered in sargasso after a storm. The sargasso is a vital component of anti-erosion on a beach, as it helps hold down the top layer of sand against the constant wind. As it gets buried by the finer sand, it helps make dunes, and when it rots, makes for a soil that seashore plants can live in, like sawgrass, sea plum, mangrove (what doesn’t mangrove grow in, yeesh) and surprisingly, palmetto. Without erosion control, you have no dunes. Without dunes, you have no barrier islands and my family home south of Patrick AFB goes bye-bye and so do the Banana River and Indian River (though they really are estuaries, but who cares as ‘river’ sounds better.)

  5. In fact, I seem to remember that around 1979-80, Miami’s beaches were eroding at a somewhat alarming rate and the solution that was discovered were:

    1. Quit mining the beaches for sand (duh).

    2. Replace sand from other sandy areas that are being dug out (from inside intracoastal waterway onto beaches (wasn’t done.)

    3. Grind glass up into ‘sand’ and toss on beaches (actually not a bad idea. And surprisingly a better use of ‘recyclable glass’ than paying to ship it to Georgia or Alabama in order for it to be rejected by the glass companies in GA or AL as too dirty.)


    4. Quit cleaning the ‘dirty’ seaweed off the beaches in order to make the beaches ‘pristine looking.’

    Mijami went with 1, 3 (for a little while) and mostly… 4.

    Within 2 years the beaches were remarkably un-eroded.

    By the way, Mijami didn’t like the looks of dead Christmas trees in their dunes like other places tried. Which is actually good because the enviro-nuts found that the pines tended to actually make the beach ‘soil’ unfriendly to the beach plants that do most of the work keeping dunes in place. These enviro-nuts, of course, were the very same ones that were promoting Xmas Trees for Dunes in order to combat erosion… It’s almost like the enviro-nuts don’t know what they’re talking about.

    By the way, Pt. 2, Ground glass for beaches actually makes pretty sand, for a season, then it gets mixed in and disappears pretty much.

  6. Yeah that looks like the high tide line of every beach I’ve ever been to here in New England. The exception is some beaches that are mostly rock, then just replace the sand with rock Seaweed is still there. As noted if you clean the beach you end up with increased erosion.

  7. Ditto everybody else. South Georgia beaches in the early 70s looked like the ones in the video, and DIDN’T erode! But of course this is another ‘man made’ disaster… sigh…

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