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Algal blooms resulting from sewage discharge may cause dolphin The same form of brain degeneration is seen in humans with Alzheimer’s disease, scientists warn in a new study.
Scientist found a type of according to deviation Alzheimer’s is affecting dolphins due to chronic exposure to toxic molecules produced by cyanobacteria, also known as blue-green algae.
And just like some humans dementiaDolphins with this condition, which are sometimes found wandering away from their homes, may also become disoriented, leading to their strandingResearchers are skeptical.
Earlier research had established that cyanobacterial blooms are increasing with global warming and inputs of nutrients into water bodies in the form of agricultural runoff and sewage discharge – all products of human activities.
Previous studies have found the toxin β-N-methylamino-L-alanine (BMAA) to be extremely toxic to nerve cells.
The latest study, published in the journal communication biology, assessed the brains of twenty common bottlenose dolphins stranded in the Indian River Lagoon in eastern Florida and found that they contained BMAA.
The study found that dolphin mortality increased during the summer months, when harmful algal blooms (HABs) are most common.
“Since dolphins are considered environmental sentinels for toxic exposures in marine environments, there are concerns about human health issues associated with cyanobacterial blooms,” said David Davis at the Miller School of Medicine.
The researchers also found that concentrations of other algal toxins were 900 times higher in the dolphins’ brains during the bloom season than during the non-bloom season.
This toxin, known as neurolarthyrogen or 2,4-DAB, has previously been shown to provoke hyperirritability, tremors, and convulsions within hours of exposure.
Many of the stranded dolphins evaluated in the study had brain tissue anomalies similar to those of Alzheimer’s patients, such as β-amyloid plaques and tau protein clusters.
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The researchers say some of the brain protein changes characteristic of severe forms of Alzheimer’s were also found in the dolphin brains.
The study also found that 536 different active genes associated with Alzheimer’s disease appeared in these same dolphins.
Earlier studies have shown that at least half of stranded bottlenose dolphins have severe to profound hearing loss.
Researchers also suggest that hearing loss is one of the main risk factors for Alzheimer’s disease and that it may aggravate dementia in humans.
“Although there are likely multiple pathways to Alzheimer’s disease, cyanobacterial exposure increasingly appears to be a risk factor,” Dr. Davis said.
“As our climate warms, harmful algal blooms will intensify. Understanding the impact of HAB exposure will help identify populations at risk for neurological diseases,” the researchers wrote.
They call for future studies to understand the role played by algal toxins in dolphin brain diseases.