Sargassum increase on VI beaches, UVI professor discusses uncertain future

Professor Edwin Cruz-Rivera, an associate Professor in the Department of Biological Science at the University of the Virgin Islands, told USVI NEWS that this is a fairly new issue we’re seeing. 

But it’s become more consistent and more predictable in recent years. 

So just what can you do about it? 

First let’s understand what it is. 

Sargassum is a seaweed that grows floating.  

Cruz-Rivera said there are about 200 kinds of sargassum but those species live attached to the bottom of the ocean. 

There are only *two types can evolve floating. 

Those species are the basis of what is called the Sargasso Sea.

That is in the North Atlantic. 

He said we’ve known about this sea for 500 years since the days of Columbus basically. 

Cruz-Rivera said in 2011 a lot more of the sargassum started washing ashore. 

He said that is where the problem lies. 

“When it gets too packed onto the shore. Then it starts breaking down and it starts rotting away and that activity starts having a number of consequences for the beach,” Cruz-Rivera said.

Those consequences include threats to nearby animal life, to seagrass and coral. 

Another thing that happens is when it starts to decompose the nutrients are released into the water which can cause more bacteria in the water. 

Animals can also find themselves getting caught in the sargassum, like fish and baby sea turtles, even dolphin deaths are related to this seaweed. 

So what’s the reason for the increase? 

“There’s no magic bullet one of the things that we’re doing going back to the nutrients. We’re dumping a lot of nutrients in the water and that acts as fertilizer for this. So we’re fertilizing the seaweed. We’re causing an increase in the seaweed. At the same time there is an increase in the average temperature of the planet because of global warming that accelerates the growth of the algae,” he added.

That ban of sargassum is growing.

Since 2011, Cruz-Rivera said it goes from the Gulf of Mexico to the coast of Africa. 

He said something like 20 million metric tons of sargassum spanning the North Atlantic.

So I asked him what’s the threat to us? 

“I can tell you that things are changing. That this is not your average Caribbean as we know it. Whether this can be managed in a sensible way will require both large and small scale views of the problem.” 

As far as removal of the sargassum he said that’s still being looked into. 

He said using it is fertilizer could be risky because the seaweed contains salt. 

“My recommendation is if you’re going to use it as fertilizer you must wash it. Now as far as your second question, remove it versus not removing it that’s another loaded question because we know that there are animals on the shoreline that depend on stranded seaweed for their survival removing it completely may actually harm the organisms that depend on this.”

Cruz-Riveras said the best option is to pick some up by hand or rake it to avoid any beach erosion by using bigger trucks to pick it up. He said taking it to the landfill as we’re seeing here isn’t really getting rid of it. 

“The question is what to do with it where do you put it and again we don’t have a real answer on that. We don’t know enough the eco system wide effects of these in order to advise on what the best course of action is.” 

Like Cruz-Rivera said this is a relatively new phenomenon in the science world. 

He said he and his team at the University of the Virgin Islands are continuing their own research in hopes of preventing the increase of sargassum on our beaches. 

In the mean time this sargassum is sticking around.

Here is a link to more of their research:

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