A new study in Nature Communications Biology connects neurotoxins found in algal blooms directly to Alzheimer's-like disease in dolphins living in Florida’s Indian River Lagoon.

Scientists from the University of Miami, SeaWorld and Blue World Research Institute found that dolphins with high levels of a toxin from algae blooms in their brains and showed warning signs of neurodegeneration.

“Dolphins serve as a sentinel species: they naturally develop amyloid and tau pathology, and their brains reveal how environmental stressors like harmful algal bloom toxins may accelerate neurodegenerative processes,” said David Davis, Ph.D., a Miller School neurotoxicologist, associate director of the Miller School’s Brain Endowment Bank and assistant research professor in the Department of Neurology. “We observed transcriptomic parallels between dolphins exposed to algal toxins and human Alzheimer’s disease — especially in pathways affecting neuronal communication and the blood–brain barrier.”

Algal blooms are becoming more common and severe and as a result, scientists say stranded dolphins have 3-thousand times more of the toxin 2,4-DAB in their brains compared to dolphins stranded outside of bloom seasons.

They found the toxins caused changes in brain chemistry and tissue that mirror early Alzheimer’s disease, including abnormal protein build-up and shifts in key genes linked to memory, brain health and Alzheimer’s disease risk.

“These results are concerning because dolphins share coastal waters with humans and face many of the same environmental risks we do,” said Wendy Noke Durden, research scientist with HSWRI. “We’re only beginning to understand how environmental change and toxin exposure affect the health of marine mammals, and what that might mean for people who share these waters. Seeing Alzheimer’s-like changes in dolphins raises questions about whether similar problems exist in other species both in the U.S and around the world.”

The research was supported by funds from the sale of Discover Florida Oceans license plate, Brevard County Tourism and Development Council, Herbert W. Hoover Foundation, and by the SeaWorld Busch Gardens Conservation Fund.

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