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A major sargassum season could be in store for Florida

Beachgoers pick their way past seaweed on Wednesday, July 11, 2018, in Sunny Isles Beach, Fla. The brownish looking seaweed variety is called sargassum and is flooding the shores of South Florida this year. (AP Photo/Brynn Anderson)
Brynn Anderson
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AP
Beachgoers pick their way past seaweed on Wednesday, July 11, 2018, in Sunny Isles Beach, Fla. The brownish looking seaweed variety is called sargassum and is flooding the shores of South Florida this year.

There aren’t many seasons in South Florida. The wet season. The dry season. Storm season. And sargassum season.

Sargassum is the formal name of the leafy brown seaweed that floats on top of the ocean and is blown ashore in Florida beginning in the spring. There’s a lot of it out in the Atlantic Ocean now and it could be headed to the sands of South Florida later this spring.

Sargassum blooms have become almost an annual event in the Caribbean since 2011. There are "strong signs" this year will be "another major year" for seaweed, according to the University of South Florida Optical Oceanography Lab.

The Florida Roundup's Tom Hudson spoke with Brian Barnes, research associate at USF's College of Marine Science. The conversation was edited for length and clarity.

HUDSON: How much sargassum is out there way out at sea right now?

BARNES: There's a lot. Right now, I think we have around 4 million tons of sargassum out there in the central Atlantic, which is a lot for this time of year. We're seeing a lot — and a lot more than we've seen in the last couple of years.

What does that mean? What does it mean if there is a likelihood of a major seaweed season?

The sargassum, when it's offshore, is a good thing. It's a habitat. There's a lot of fisheries, a lot of animals, invertebrates that depend on it. A major sargassum year just means that there's a lot of sargassum in this area that we call the Great Atlantic Sargassum Belt. It goes from Africa all the way in through the Caribbean and sometimes impacts Florida. A major sargassum season means we have a lot of sargassum. Some of this can roll-up onto beaches and start causing economic environmental issues for those areas. But just because there's a lot of sargassum in the greater Atlantic doesn't mean we're going to have those severe impacts.

What does the amount of sargassum here in an early calendar year tell us about the marine or environmental conditions of the water?

Sargassum is just like a typical plant that you would have around your house. As long as you've got a seed population and then the right nutrients, the right temperature environment and so forth, then the organism will start to grow and multiply and expand. We've seen an explosive growth in the central Atlantic. The question now becomes, do the winds and the currents carry all that sargassum into areas in the Caribbean and eventually into Florida that it might cause problems for beach goers and so forth?

A screenshot of the Dec. 2024 sargassum bloom in the Atlantic Ocean.
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University of South Florida Optical Oceanography Lab
A screenshot of the Dec. 2024 sargassum bloom in the Atlantic Ocean.

What about the risks to the peninsula and both sides of the peninsula and the panhandle? Can it get around the straits of Florida into the Gulf?

It comes in between the Yucatan Peninsula and Cuba, and then it rides the Loop Current, which kind of goes up north a little bit and then turns right back around. We don't see many impacts, many landings of sargassum on the west coast of Florida just because it's riding that Loop Current all the way out the Straits of Florida. Once you get off into the Keys, you can see large inundations in the Florida Keys and the Miami area going all the way up the Treasure Coast.

READ MORE: Could new invasive seagrass in South Florida doom one of the best defenses to climate change?

What about the timing if it is to blow into Florida?

The earliest we typically see any kind of major inundations in Florida would be March timeframe. But usually the more substantial impacts are in May and into the summer months. It's really early to make any predictions about what might be impacts to Florida other than that, if they occur, there'll be several months away.

You mentioned potential economic impact because it can crowd beaches and there's an expense to remove it. Is it dangerous at all? Should we not touch it?

It’s not great to be in and around the sargassum, but the impacts to human health are just the smell and respiratory distress from the decaying matter as it's washed up on beaches.

If you've got a beach day, do you look at that sargassum forecast before you head out with your umbrella and chairs?

Yes and no. The sargassum forecast is a monthly retrospective now. It provides data on the level of the entire ocean. What we're working on now is getting into that granular level – this particular beach (for example), impacted on this particular day rather than something like the Florida Keys may get some impacts in a couple of months. That is kind of the frontiers that we're pushing with some of our new funding from NOAA – to try and get into that granular level of being able to advise beachgoers as to whether a particular beach would be impacted by sargassum on a particular day or week.

If you're successful with that, might we see a new type of flag at the beach? There's a marine life flag. There's a wind flag. Might there be a sargassum flag?

I like that. The surf warning. Red tide warning and the sargassum warning. It sounds good.

Tom Hudson is WLRN's Senior Economics Editor and Special Correspondent.
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