South Florida could be heading toward another summer of slime

A massive buildup of blue-green algae in Lake Okeechobee threatens the state’s East and West coasts. University of Miami phytoplankton and water quality experts address the challenges that another massive red tide outbreak would pose.

Right now, it is just a waiting game. But if the unsightly blue and green gunk that now covers 500 square miles of Lake Okeechobee is any indication, this summer South Florida could be ground zero for a massive algae outbreak on par with, or even worse than, the bloom that contaminated waterways on the state’s East and West coasts three years ago.

“There’s a pretty good chance for it,” said Larry Brand, a phytoplankton expert at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, who has been monitoring algae levels in the lake via National Oceanic and Atmospheric Administration satellite images.

Precipitation, he said, will determine just how bad that outbreak could be. Water levels in Lake Okeechobee—where thick mats of blue-green algae, fueled by rising temperatures, have been building up for weeks—are already high. And with forecasters calling for an above-average hurricane season, it is only a matter of time until the U.S. Army Corps of Engineers will have to release water from the lake into the Caloosahatchee and St. Lucie rivers to prevent a breach in the aging Herbert Hoover Dike, Brand explained. 

Patches of cyanobacteria, the scientific name for blue-green algae, are already present in the Caloosahatchee, he noted. “So when the corps discharges more water, algae will continue to travel down to the estuaries,” said Brand, a professor of marine biology and ecology. And if the release is large, the algae will flow all the way into the Gulf of Mexico, where the algae-laden freshwater will mix with the ocean’s saltwater, stimulating a chemical reaction that often spawns red tide.

Low levels of red tide have actually existed along parts of the state’s southwest coastline since last November, Brand said. That is when the corps, responding to a rise in Lake Okeechobee water levels caused by three times the normal amount of rain falling in South Florida that month, released a modest amount of water from the lake. “It’s not a huge outbreak, but it’s there,” he explained. “It started at the mouth of the Caloosahatchee River. Then it spread north, and it’s all the way up to Sarasota and a little bit into Tampa Bay.”

In 2018, a massive red tide event devastated Florida’s Southwest Coast, killing marine life and sickening residents and visitors. 

Brand can vividly recall the hundreds of media images that illustrated the impacts of that bloom: thousands of sea creatures—from dolphins and manatees to sea turtles, snook, and trout—washing ashore on several of the region’s normally scenic beaches after perishing from the neurotoxins produced by the algae.

The persistent bloom lasted for months, crippling tourism-related businesses in Charlotte, Manatee, Sarasota, and other counties. The state tourism organization, Visit Florida, created programs to help those businesses recover. But many were severely impacted again amid the COVID-19 shutdowns. Now, another massive red tide outbreak is imminent, threatening to curtail the progress those businesses have made after the pandemic restrictions were lifted.

“This is supposed to be the summer that everyone recovers and when everyone is coming to Florida’s beautiful beaches,” said Kathleen Sullivan Sealey, a professor of biology in the University’s College of Arts and Sciences, who has been studying water quality and coastal ecology in Florida for more than three decades. “But even a small algal bloom is a hazard to people’s health, so it could be an economic disaster,” she said.

Hoping to stave off another catastrophe like the one in 2018, environmentalists have urged Florida Gov. Ron DeSantis to act under an emergency order. But he has not responded to the request, instead asking the South Florida Water Management District to send as much water south as possible. 

Such a strategy, however, will most likely have only limited success if any, as water levels in the northern part of the Everglades are already high because of excessive rainfall the past year, according to Brand.

What’s more, a 1988 federal lawsuit filed against Florida limits how much water the state can divert to the Everglades, Brand pointed out. In that suit, the U.S. government alleged that water discharged onto federal lands from agricultural sources contained high levels of phosphorus and other nutrients in violation of state water-quality standards. The two parties reached a settlement, establishing the Everglades Forever Act that required the state to establish a numeric limit on phosphorus.

Pumping too much water to the Everglades would also imperil species like the Cape Sable seaside sparrow, an endangered bird endemic to Southern Florida that is incapable of nesting when water levels in the Everglades are too high. 

Still another issue: releasing excessive amounts of water into Florida Bay, which is located between the southern end of the Florida mainland and the Florida Keys, would only produce algae blooms in that region, according to Brand.

Coming up with an effective way to lessen the algae impacts is crucial, as more and more studies are linking aerosolized cyanotoxins to long-term detrimental health outcomes. A recent study led by Miller School of Medicine molecular and cellular pharmacologist Grace Zhai, for example, found that exposing fruit flies at an early age to aerosolized blue-green algae significantly shortened their lifespan, with reduced survival rates becoming evident as early as 10 days after exposure.

And in another study, neurology professor David Davis linked a toxin produced by blue-green algae to amyotrophic lateral sclerosis, or Lou Gehrig’s disease.

Aside from human health concerns, the impending outbreak will likely have a catastrophic impact on marine life, said Jill Richardson, program director and senior lecturer in marine ecosystems and society at the Rosenstiel School. She noted that local manatee and dolphin populations, which are still reeling from the persistent 2017 to 2019 red tide outbreak, are of particular concern. 

“Adding insult to injury, Florida manatees are currently experiencing record high mortality rates, so adding another potential stressor to an already unbalanced ecosystem could be catastrophic,” Richardson said. “The repeated and confounding impacts of these events are potentially devastating. These populations of marine mammals just don’t have enough time to recover between events.” 

Sealey states that Florida politicians need to adhere to the Comprehensive Everglades Restoration Plan, which recommended that the government buy all the agricultural land south of Lake Okeechobee, clean the lake water at a treatment plant, and then allow that water to flow over its southern border through the Florida Everglades. Before the state’s development boom of the 1930s, this is how the lake maintained its water levels naturally. But after a devastating 1926 hurricane flooded many homes in Central Florida, the desire for more arable land prompted the Army Corps to build up the southern edge of the lake, stopping extra water from flowing south into the Everglades.

“The Everglades restoration plans that have been scientifically laid out over decades should be sacred,” Sealey said, noting that many recent state leaders have delayed plans to restore the southern flow of Lake Okeechobee. “Anytime the government of Florida held back on restoration, they were just exacerbating the possible catastrophes.”

Until the plans accelerate, she noted, the problem of algal blooms will continue to haunt Florida.

Years ago, Sealey studied Martin County’s attempt to clean the algae-laden water flowing out of the St. Lucie River from Lake Okeechobee. Local leaders spent thousands of dollars planting oyster beds at the mouth of the river to help protect their beaches from another red tide event. But the high levels of blue-green algae killed all the oysters, Sealey reported.

“The local governments trying to do better coastal management are completely undermined by this discharge from Lake Okeechobee,” she said.

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