Sargassum ~ Floating Habitat with a Big Smell!

Sargassum at sea (image by Tam Warner Minton/Flickr)

Sargassum grass is a type of brown algae that floats in small patches or gathers into large masses and can be found in every ocean except the Antarctic.  The first written report of sargassum dates back to 1492 by Christopher Columbus (don’t get me started on the different names I have encountered for this famous explorer!).

Like every living force, sargassum has some great properties and some that we could do without.  Here in The Yacht Club at Palmas del Mar, Puerto Rico, the big negative is the smell emitted by the algae as it dies on the shore line and releases sulphur compounds that smell like rotten eggs on steroids!

But this floating grass also has benefits for the ocean.  As many as 52 varieties of fish were found to take shelter and find food within this floating algae off of North Carolina.  Sargassum grass offers a moving habitat for fish in parts of the ocean where no other is available.

Interestingly, a study by the North Carolina National Estuarine Reserve states, “The Sargassum community occupies such a large dimension of the upper water column (up to 3 m depth) and is typically so diverse that one gear or collection method cannot effectively sample it all.” 

In studying the algae columns, researchers found that there is something of a layering habitat within the sargassum where smaller fish live in the algae, slightly larger juvenile fish live below the grass and larger predators such as dolphins swim further down in the water.

Small gas-filled spheres that look like berries keep the seaweed afloat. (naturetime.worpress.com)

In recent years, sargassum has become so prolific that it has caused issues along some beaches, creating foul smells as it rots on the shore, deterring vacationers from visiting popular resort destinations.  Additionally, the grass can be so dense in places that it inhibits the movement of hatching sea turtles on their way to the water, causing them to die before reaching the ocean.  But once in the water, small turtles also find food and shelter within the sargassum algae.

The benefits of sargassum are not limited to fish and turtles.

Since the eighth century, traditional Chinese medicine has used sargassum as a natural diuretic and for treating goiters and thyroid deficiencies. Additionally, the algae is nutrient dense and contains carbon, making it an excellent fertilizer.  The government of Tobago is encouraging farmers to use this algae as fertilizer on crops.

Experts believe these main factors are causing the increase in sargassum grass;

1. higher ocean temperatures which allows this tropical plant to thrive
2. polluted waters carrying higher nutrients that act like a fertilizer for the sargassum
3. changing “liquid boundaries” in the ocean caused by storms and high winds help spread sargassum throughout the oceans

Sargassum drift near The Yacht Club only two weeks after a clean up.

Most days as I head out for my walk here at Palmas del Mar, I hold my breath as I pass one area ripe with rotting sargassum grass.  Even though the marina is doing all it can to collect and remove the plant, I gag a little on days when the smell is strong.

So I’m glad I researched sargassum and can at least appreciate the benefits it offers instead thinking it is just a “smelly weed.”  Perhaps the next time you are confronted with the obnoxious odor of this algae as it decomposes, you will be able to consider its’ benefits like I am now and both of us will resent the smell a little less.

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