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Breakthroughs in Science: Toxic algae blooms
Craig Patrick reports.
FORT MYERS, Fla. - Every summer, blooms of toxic blue-green algae reappear across Florida, turning lakes and rivers bright green, blue or forming brown clumps. They pose a serious threat to public health, pets, and wildlife.
What we know:
Dr. Barry Rosen, an ecologist at Florida Gulf Coast University (FGCU), has spent years collecting and studying samples.
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"I have a collection of algae — cyanobacteria — that from around the country actually," he said, pulling out a sample from his lab. "This is a very thick culture of cylindrospermum… and it’s thriving."
Cyanobacteria emit different types of toxins — many still under investigation. The most common variety found in Florida ponds, Microcystis, produces microcystin, a known hepatotoxin that can damage the liver and kidneys.
"Microcystin is a known hepatotoxin," explained Dr. Mike Parsons, a marine science professor at FGCU and member of Florida’s Blue-Green Algae Task Force. "If a person or animal is exposed to a high enough dose, it could actually result in death."
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Across Florida, there have been multiple reports of dogs dying just hours after drinking algae-contaminated water.
"She walked a few feet, and she was kind of rocking, and she just went over," one pet owner recalled.
By the numbers:
More than 10,000 species of blue-green algae exist globally. It also only takes one day for a dog to die after drinking algae-contaminated water.
The backstory:
Cyanobacteria are ancient organisms that thrive in warm, nutrient-rich water — conditions increasingly common due to human pollution. Decades of agricultural runoff and nutrient dumping have supercharged algae blooms, especially in stagnant or slow-moving water bodies like Lake Okeechobee.
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The poisons they emit vary by species. In addition to microcystin, researchers have focused on a neurotoxin called BMAA (β-Methylamino-L-alanine). It has been found in Florida waters and correlated to ALS, Alzheimer’s disease and other neurodegenerative disorders.
"We know it’s a neurotoxin, and we know cyanobacteria produce it," said Dr. Parsons. "When their blooms occur, people are potentially at risk of exposure and then result in neurological symptoms."
What we don't know:
While scientists have detected alarming levels of toxins in water, many questions remain:
- What levels of BMAA or microcystin exposure are dangerous to humans over time?
- Can breathing in airborne toxins from dried algae lead to any long-term health damage?
- Is there a definitive link between algae exposure and neurodegenerative disease?
"In testing, you’re not necessarily getting true BMAA," cautioned Dr. Rosen. "You could be picking up another amino acid."
"We’re stuck in a rut," Dr. Parsons said. "Without a reliable test for BMAA, we can’t move forward in understanding the true risk."
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Timeline:
- 1950s (Guam): Researchers linked an ALS-like disease cluster to people eating fruit bats contaminated with BMAA.
- 2017: Release of a Ohio State University study linking toxic algae blooms near Stuart, FL, to a cluster of non-alcoholic liver disease in humans.
- 2018–2025: Studies in Florida show the presence of cyanobacteria in airborne samples, seafood, and even human nasal passages.
What's next:
Scientists are pushing for more comprehensive studies, better testing standards, and greater public awareness. Meanwhile, new technologies are helping researchers simulate how airborne toxins move and enter the human body.
Florida lawmakers and environmental regulators are also under pressure to improve water management policies that prevent nutrient pollution — the root cause of these blooms.
Tuesday night, FOX 13’s Breakthroughs in Science series will continue with a deep dive into what went wrong with water policy in Florida and the technological innovations now offering hope.
The Source: This report is based on original interviews with experts from Florida Gulf Coast University and the University of Miami and field research conducted across Florida. Experts cited in this report include: Dr. Barry Rosen, FGCU ecology professor; Dr. Mike Parsons, FGCU marine science professor; Dr. David Davis, University of Miami neurology professor and Dr. Larry Brand, University of Miami marine science professor.