In an alarming new study that has implications for people living along the Florida coast, scientists have discovered that dolphins here appear to be suffering from a condition similar to Alzheimer's disease caused by toxins from common algae.

University of Miami researchers examined the brains of 14 dolphins, some of which had beached themselves, from Florida to Massachusetts. Half of the marine mammals were found stranded in areas with frequent harmful algal blooms: the Banana River, Indian River Lagoon, the Atlantic Ocean, and the Gulf of Mexico.

Thirteen of the dolphins' brains were riddled with lesions and levels of an algae toxin called BMAA that were 1½ times what's seen in brains of humans who die of Alzheimer's disease.

"We are looking into the possibility that BMAA is causing these lesions, or at least accelerating them," said Dave Davis, lead author of the study and a research assistant professor at University of Miami's Brain Endowment Bank.

The University of Miami study, published this month in the journal PlosOne, suggests the toxin poses similar risks to humans who live along the coast or eat lots of seafood from algae-prone areas. The slow-acting toxin has uncertain health risks for coastal residents who eat or breathe it for decades, the authors say. A warming planet that fuels more frequent toxic algae blooms may worsen the threat, especially in Florida, they say.

The researchers found chronic exposure to the toxin, β-methylamino-L-alanine (BMAA), can trigger Alzheimer’s-like abnormal protein "tangles" in the brains of dolphins. The "tangles" block the ability of brain cells to function, communicate or repair themselves, so they die.

Past studies also have suggested a link between the BMAA toxin, Alzheimer's and other neurological diseases in humans, such as Parkinson’s and amyotrophic lateral sclerosis, or ALS. But the scientific jury is out on whether the toxin is a direct cause of those diseases.

The toxin is associated with common algae.

"As far as we can tell pretty much all blue-green algae (produce BMAA)," said Larry Brand, professor of marine biology and ecology at UM's Rosenstiel School of Marine and Atmospheric Science and a co-author on the study. "Some produce a lot more than others. We don't really know for sure what the function of these toxins are," he added.

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BMAA toxin also turns up in crabs, shellfish and other seafood dolphins and humans eat. The toxin builds up in marine life as it moves up the food chain during Florida's frequent blue-green algae blooms. "Most likely they're (the dolphins) getting it in the fish," Brand said.

But seafood is not the only route of exposure. BMAA also gets into the air as an aerosol, so people near a water body with algae blooms breathe it in, similar to brevetoxin from Florida's red tide.

Other research in recent years shows living near lakes with frequent blue-green algae blooms — where breaking waves can aerosolize BMAA — has been linked with a higher risk of ALS. Army physicians first described a mysterious ALS-like disease among the indigenous Chamorro villagers in the 1950s.

"I think this (latest) research is timely, fascinating and significant," said Greg Bossart, head pathologist at Georgia Aquarium and an adjunct professor at University of Miami, who did not participate in the most recent study. "I think this is an excellent example of how dolphins are going to tell us about the health of the oceans and human health."

Finding BMAA in lagoon dolphins' brains is not surprising, Bossart said, given the severity of algae blooms in recent years. "Whether or not it causes the neurodegenerative legions is the $64,000 question," he added.

The dolphin with the highest BMAA level in its brain was from the Gulf of Mexico, in Southwest Florida. Dolphins from the Indian River Lagoon had the third highest levels of the toxin.

The researchers say BMAA might be causing dolphins to wander far astray from usual routes and impacting reproduction.

The researchers also suspect a toxic form of mercury could be worsening BMAA's impacts on dolphin brains. They plan further study of that theory.

"The potential combined neurotoxicity of BMAA and MeHg (methylmercury) underscores the impending impact of climate change on the marine food web," the authors wrote.

While scientist have yet to prove for sure whether BMAA causes Alzheimer's disease, a leap forward with that suspected link came in a 2016 study that found similar protein deposits or "tangles" in brains of monkeys fed fruit dosed with the same amino acid that's in blue-green algae species common in Florida.

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In that study, monkeys fed fruit dosed with BMAA developed the hallmark brain "tangles" and abnormal protein deposits similar to Pacific Islanders who died from Alzheimer's. They found those hallmarks of both Alzheimer’s disease and an unusual illness suffered by Chamorro villagers on the Pacific Island of Guam.

Pacific Islanders with this unusual condition also suffer from dementia and symptoms similar to Alzheimer’s disease, ALS and Parkinson’s disease.

BMAA's scourge on the brain appears to be a problem of mistaken identity. To the body, BMAA looks similar to serine — an amino acid needed for building proteins.Foods high in serine include soy, eggs and nuts. But when the body takes up BMAA and uses it instead of serine to build new proteins needed by the brain, the proteins wind up misshapen and brain cells cease to function properly.

"You end of with this tangled up protein," Brand explained.

In one 2016 study, vervet monkeys fed equal amounts of BMAA and a the naturally occurring dietary amino acid, called L-serine, had a reduced density of tangles, suggesting diets with L-serine could lower the risk of neurological diseases.

Genes make some more susceptible to neurological diseases, scientists say, but it takes an environmental trigger for people to develop the diseases.

Seafood remains the main concern. In a 2010 study, Brand found the highest levels of BMAA in blue crabs, shrimp and pufferfish among the samples he examined in South Florida. Biologists now suggest limiting consumption of certain types of seafood high in BMAA. But because of a lack of data, there are no consumption guidelines specific to BMAA

Absent guidelines, moderation is a key preventative cure, the researchers said.

"The take away message is where you get these blooms of blue green algae, I would not recommend eating the seafood from there," Brand said. "If you're eating one meal a month, that's probably not a big deal."

Bossart sounds a louder alarm.

"I think it's a warning sign for us. It's a classic miner's canary," he said. "We better take note of this kind of research. I personally wouldn't eat anything out of the Indian River, based on what our research has found over the past 16 years."

Contact Waymer at 321-242-3663 or jwaymer@floridatoday.com. Follow him on Twitter @JWayEnviro.

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