– 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, University of Miami researchers said.

The study, published in the journal PLOS One, 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 dolphins and their complex brains could provide a key sentinel for the potential threat from toxic algae blooms to humans.

“It goes to show the health of marine animals and water quality,” said David Davis, lead author and a University of Miami Miller School of Medicine neuropathologist. “Everything’s directly related.”

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

For this study, researchers looked at brains from 14 dead dolphins, including seven Florida bottlenose dolphins that beached themselves in 2005 along the Atlantic, the Indian River Lagoon, the Banana River and Gulf of Mexico where algae blooms frequently occur. They also looked at seven common dolphins found dead in Cape Cod Bay off Massachusetts in 2012.

All but one dolphin, which died from a boat strike, had BMAA in their brains as well as signs of degenerative disease. Making the connection in dolphins is significant because it provides a window into a more complex brain and one with higher functions like a human’s.

Looking at dolphins in the wild also gives scientists a more realistic model of how the toxin accumulates. Davis said, “If you have these dolphins feeding in the same marine food web as humans, potentially eating the same things as humans, that’s why we say it serves as a sentinel.”