Something fishy is happening to Flipper. Dolphins living in Florida’s Indian River Lagoon are beginning to show warning signs of a form of neurodegeneration similar to Alzheimer’s disease. The cause? Harmful algal blooms caused by climate change that are exposing dolphins to high levels of a neurotoxin.
The discovery of the neurotoxin in the dolphins’ brains was made in a collaborative study that included scientists from the University of Miami’s Miller School of Medicine and Rosenstiel School of Marine, Atmospheric and Earth Science, as well as investigators from Hubbs-SeaWorld Research Institute (HSWRI), Brain Chemistry Labs and Blue World Research Institute.
Straight to the Brain
The study is one of the first to connect neurotoxins found in algal blooms directly to brain changes associated with Alzheimer’s-like disease in a wild marine mammal. It also illustrates how warm water and nutrient pollution, which fuel these blooms, may impact wildlife health.
“Dolphins serve as a sentinel species,” said David A. Davis, Ph.D., a neurotoxicologist, associate director of the Brain Endowment Bank and assistant research professor of neurology at the Miller School. “They naturally develop amyloid and tau pathology, and their brains reveal how environmental stressors like harmful algal bloom toxins may accelerate neurodegenerative processes. 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.”
As our climate warms, algal blooms are becoming more frequent and severe, posing significant risks to marine ecosystems and public health. The study builds on ongoing research by the Brain Endowment Bank that investigates the impact of neurotoxins from algal blooms and their association with Alzheimer’s-like disease.
“Dolphins serve as a sentinel species. Their brains reveal how environmental stressors like harmful algal bloom toxins may accelerate neurodegenerative processes.”
Doomed by Diet
During bloom seasons, dolphins stranded in bloom areas were found to have 2,900 times more of the toxin 2,4-diaminobutyric acid (2,4-DAB) in their brains compared to dolphins stranded outside of bloom seasons. Alongside these toxins, researchers observed changes in dolphin brain chemistry and tissue that mirror early Alzheimer’s disease, including abnormal protein buildup and shifts in key genes linked to memory, brain health and Alzheimer’s disease risk.
The results also align with recent research showing that ecosystem disruption in Florida’s Indian River Lagoon has led to major changes in dolphin diet and prey availability.
“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, a 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.”
