Sargassum Superbloom Is Stinking Up Florida Beaches

Great swaths of Sargassum algae, originating from Atlantic waters off South America, are washing up onto Florida coastlines and into basins and canals. More than just an inconvenience, they’ve also become cause for concern on a grander scale.

Usually considered a vital habitat for marine species, providing both food and protection, the massive amounts of it currently washing up on Atlantic beaches—from the Florida Keys to Cape Canaveral, and in even greater quantities in the Caribbean and Mexico—can actually be harmful to ocean life, besides being a nuisance for residents and beachgoers.

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When mats of the macroalgae wash into basins and inlets, the water becomes oxygen-depleted enough to start killing off sea life, as occurred last week at Tavernier boat basin in a Florida Keys community. The deep and usually clear basin became a death trap for moray eels and untold numbers of parrotfish, snapper and other species that were found afloat, dead and decaying.

Ensnared among the clumps of thick sargassum in the shallows and on shore, nesting sea turtles also struggle to reach the beaches, and turtle hatchlings are dying without a clear path to the ocean.

“Sargassum was something that was really unique and deserving of protection,” Brian Lapointe, Ph.D., a research professor for Florida Atlantic University’s Harbor Branch Oceanographic Institute, told the Florida Keys Free Press. “All of a sudden, global change is going on and sargassum is becoming harmful. Now it’s the largest harmful algal bloom on Earth.”

Ever since a worrisome explosion of the thick, brown seaweed appeared back in 2011, the snowballing predicament has been plaguing island nations in the Caribbean and Mexico, but the ever-expanding scope of the issue means it's a problem for Florida this year, too.

Scientists are speculating that the excessive algae may actually be among the unforeseen consequences of deforestation in South America. “There has been a lot of deforestation in the Amazon Basin and a major increase in fertilizer use,” Lapointe said. “Coupled with extremely heavy rain, as a result of global climate change, that feeds the bloom.”

Easterly winds this time of year have fueled the spread of sargassum off South America and the Gulf of Mexico, where the Loop Current carries it through the Florida Keys and onto the mainland’s coastline. When the stuff rots, it releases toxic hydrogen-sulfide gas, making seashores smell like rotting eggs. While there’s no evidence that Florida’s tourism industry has yet taken a major hit owing to the issue, Lapointe verified that the effects on tourism in the Caribbean have already been catastrophic.

2018 was a record year for sargassum blooms, and, according to Chuanmin Hu, a University of South Florida professor specializing in optical oceanography, “Last year the bloom never ended. This time of year is when it’s at its worst and there is no sign of an improved situation. It does not look good.”