Researchers find blue-green algae toxin in dolphins that also have brain disease

A toxic blue-green algae that choked the Fort Myers-Cape Coral area last summer has shown up in dolphins with brain disease. 

Researchers tested 14 stranded dolphins from Florida and Massachusetts, areas the study notes as having relatively frequent harmful algal blooms. 

All but one of the dolphins test positive for the cyanobacterial neurotoxin known as BMAA as well as brain disease. 

"The question is: are they a sentinel species," said Deborah Mash, a University of Miami researcher who was part of the team that published the work. "Are they showing us something that could be affecting us as well?" 

The article published last week in the peer-reviewed journal PLOS One. 

A blue-green algae bloom started last summer in Lake Okeechobee and quickly spread to the Caloosahatchee River, where it festered for months. 

Some canals in Cape Coral and North Fort Myers were literally blanketed with blue-green algae growth, which can range in color from a pea soup to a vibrant baby blue. 

The bloom went on for months, and then-Gov. Rick Scott declared a state of emergency for impacted counties. 

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Chronic and acute exposure to those toxins can be harmful to humans and animals, causing anything from severe dermatitis to organ failure and death.

But many of the long-term health implications are unknown. 

Larry Brand, also with the University of Miami, was part of the research and said the link between BMAA toxins and brain disease should cause public concern. 

"Hopefully, people know not to go swimming in that water or eat seafood in that water," Brand said. "But people that live in those Cape Coral canals don’t have the choice of breathing the air, unless they move."

Brand said exposure is particularly frightening because there are no immediate symptoms. 

"As far as we know it has no short-term effects but as you accumulate these you accumulate brain tangles," Brand said, "and over the years you come down with these brain diseases." 

Brain tangles are associated with Alzheimer's and are thought to degrade brain functions. 

The PLOS One article says harmful algal blooms like blue-green algae are becoming more frequent in estuaries and freshwater lakes, most likely fueled in part by climate change. 

Research has shown that diets high in BMAA trigger neurodegenerative changes in animals like primates.

The report pointed to research that shows an increased rate of neurodegenerative diseases in people who live close to lakes with frequent cyanobacteria blooms.

"The presence of BMAA and neuropathological changes in the stranded dolphin brain may help to further our understanding of cyanotoxin exposure and its potential impact on human health," the article says.

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Calusa Waterkeeper John Cassani spent much of last summer speaking to local groups about water quality concerns over the blue-green algae. 

He said the article reinforces his concerns that local waters could be detrimental to residents and visitors. 

"These results are pretty insidious because we’re seeing strandings and mortalities when there currently isn’t a harmful algal bloom," Cassani said. "These dolphins are feeding on fish and crabs and other aquatic animals and are building up the BMAA in the food chain."

Mash said more work needs to be done on connections between blue-green algae and brain disease.  

"We’re not saying that BMAA causes Alzheimer's," Mash said. "It’s linked because we see that in the pathology. But it’s a small study and we need to have much larger studies before we can make conclusions."

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