4 facts about a slimy problem invading South Florida beaches
Wednesday, June 27, 2018, 18:11 - A slimy problem is growing on the beaches of South Florida. Thick rafts of a seaweed species known as sargassum have caused resorts to close in the Caribbean, and now they're piling up on Florida's Atlantic beaches in foul-smelling heaps. But what's behind the invasion? Well, that's part of the mystery.
Sargassum seaweed, as the name might suggest, has always been present in large quantities in the Atlantic Ocean; it's how the Sargasso Sea off the east coast of the United States got its name. But in the past few years, the open-ocean dwelling plant hasn't been satisfied to stay offshore, launching massive invasions on beaches of the Caribbean and South Florida. And while it's not dangerous to people, per se, it poses some major problems.
Sargassum seaweed in Miami. Image courtesy University of Miami.
1. It obstructs beach use, and smells terrible
Sargassum itself is not toxic, but once it washes ashore and begins to decay, it releases a strong, unpleasant odor, similar to rotten eggs. Truckloads of the stuff clogging beaches in Barbados, Guadaloupe, and Tobago forced officials to issue advisories to residents, while a major hotel in Antigua, The St. James Club, has had to close its doors until October 1. And it can be more than just a nuisance to beach goers. According to experts at the University of Miami, decaying mats tend to play host to biting insects like sea lice, while floating mats can trap floating debris.
2. It's bad for some sea life
While we land-dwellers can avoid the stuff, sea life isn't as lucky. Sargassum can grow as high as 2 feet, and traps crabs, sea turtles, as well as blocking sunlight from reaching the local seagrasses and corals that live on the ocean floor beneath it. In fact, it's a double-whammy for local sea life, as the organisms that work to decompose the sargassum also use up oxygen and nutrients in the water the locals need.
When it's in its proper place, there are some sea creatures who rely on sargassum for food and shelter, including various kinds of fish. Sea turtles have a somewhat complicated relationship with the plant; on the one hand, small turtles make use of it for shelter and transportation. On the other, beached sargassum clogging turtle nesting beaches grounds can prevent nesting.
3. No one knows why it's spreading
The first major bloom, or beaching event, in the Caribbean, Gulf of Mexico and Florida, happened in 2011, and since then two other large-scale events have happened; one in 2014-2015, and one now. Before that, there had never been a widespread event reported. Satellite data from before 2011 seems to confirm this - an oceanographer from the University of South Florida, Chuanmin Hu, told Science that the region is actually "largely free of seaweed" in images from prior to 2011.
Satellite images from earlier this year indicated that 2018 would be another major bloom year for Sargassum. The Optical Oceanography Laboratory at the University of South Florida says that 2018 is in fact on track to be a record-setting year for the seaweed in the Caribbean and central West Atlantic, but the reasons behind the record-high bloom are "yet to be determined".
According to researchers at the University of Miami, it seems like this inundation represents a 'move' in the seaweed, rather than new growth. Some research suggests that the unusual beachings may be the result of anomalous winds over the Atlantic, pushing both the waters of the Sargasso Sea, and its mats of seaweed, in 'unusual ways'. Another study suggests that, at least in the case of the 2011 event, the seaweed came to the Caribbean from the tropical Atlantic, east of Brazil.
Lew Gramer, a scientist at the University of Miami, suggests that climate change may have played a role, as the initial 2011 event was preceded by unusual pressure patterns in the North Atlantic. "No such persistent low in the NAO has occurred since early 2010," says Gramer. "However, now that the table has been set for Sargassum in the western equatorial Atlantic by the 2009-2010 NAO low, the ocean and wind conditions which bring Sargassum en masse from the equatorial Atlantic through the eastern Caribbean, Yucatan Strait, and into the Straits of Florida may continue to occur."
4. We can't do anything about it - or can we?
It probably stands to reason that, if we don't know why it's on the rampage, we can't do much to stop it. For residents of the Caribbean, there's serious concern that this will be the 'new normal' that they'll need to adjust to; seriously disrupting fishing and tourism industries, among others. Iris Monnereau, a regional project coordinator for the Food and Agriculture Organization of the United Nations in Christ Church, Barbados, told Science she’s particularly worried about this year, noting that the blooms visible in satellite imagery dwarf those of previous years. “You can’t solve the problem; you can’t put up a wall or anything,” she says. “It’s difficult to go forward.”
There are some trying to lead the charge in adaptation, however. Researchers in Barbados are investigating the use of sargassum as a sustainable energy source and fertilizer. Kirk Humphrey, Minister of Maritime Affairs and the Blue Economy in Barbados called the research "innovation in an area that needs innovation," saying, “It is a big problem. The magnitude is massive…Turn it into an opportunity, either an economic activity, a food source or as an employment opportunity."