Poisoned dolphins show signs of dementia

Toxins produced by blue-green algae that have increasingly polluted Florida waters have been found in dead dolphins that also showed signs of Alzheimer’s-like brain disease, according to a new study led by University of Miami researchers.

The study, published in the peerreviewed journal is the first to show detectable levels of the toxin, commonly called BMAA, in dolphin brains that also displayed degenerative damage similar to Alzheimer’s, Lou Gehrig’s disease and Parkinson’s in humans.

While more work needs to be done to determine whether the toxins cause the disease, the study concludes that dolphins and their complex brains could provide a key sentinel for the potential threat from toxic algae blooms to humans.

The findings add to a growing body of research that focuses on the health threat from harmful algae blooms, which climate scientists warn could worsen as the planet warms.

South Florida is particularly vulnerable, with a long coastline, rivers and estuaries, and an agricultural industry and swelling population that continue to feed blooms with pollution from fertiliser and sewage.

Last year, nearly 150 dead dolphins turned up in Florida waters after a widespread red tide along the Gulf Coast coincided with freshwater blue-green algae washing down the Caloosahatchee River.

Two years ago, University of Miami researchers confirmed high levels of algae toxin in sharks, concluding that they accumulate the toxin in their brains over time, and warned against eating shark.

The connection between the toxin and brain disease is still relatively new, and not without controversy.

Scientists discovered the link after a botanist visiting Guam to research cancer took another look at a decades-old mystery surrounding a degenerative brain disease which affected nearly every household in a small village, leading researchers to focus on the seed from cycad plants, a staple of the villagers’ diet.

The seeds contain BMAA, but researchers concluded that the villagers could never consume enough to make them sick. A botanist found the connection when he discovered that the villagers also ate fruit bats, which feasted on the seeds and had a much higher concentration of BMAA because it accumulated in their bodies over time.

A decade later, the University of Miami’s Brain Bank repeated the study and found BMAA in the brains of people suffering from the degenerative diseases.

Since then, more studies have looked at higher incidences of Lou Gehrig’s disease in people who live near lakes with frequent blooms.