Algal blooms are bad, that much we know. But just how bad are they? Photo: Unsplash
Researchers trying to find out why dolphins strand themselves found something interesting: some of them could have a disease similar to Alzheimer’s — and they think that algal blooms might be the cause.
Marine mammal strandings are relatively common occurrences. In July of last year, the largest-ever mass dolphin stranding happened off the coast of Cape Cod. The same month, 77 pilot whales died after a mass stranding event in Orkney, Scotland. In Florida, strandings happen surprisingly frequently, especially in the summer.
You know what else happens in the summer, off the coast of Florida? Algal blooms. Those blooms are getting worse as our waters warm and we continue to pump fertilizer-filled runoff into the sea.
Algal blooms can be disastrous to the animals that live near them. Toxins like domoic acid can build up in the food chain, concentrating itself in the organs until, for example, sea lions are killed from it.
Scientists looking at what causes dolphin strandings decided to have a closer look at Florida’s Indian River Lagoon, since the area has been the location of numerous stranding events.
“To find out,” IFLScience reported, “a team of researchers examined the brains of 20 common bottlenose dolphins (Tursiops truncatus) that were found stranded in the lagoon between 2010 and 2019, looking for signs of toxin exposure and changes in the brains’ gene expression, cells, and structure.”
The researchers found that, during algal bloom season, the dolphins had a high concentration of a neurotoxin called 2,4-diaminobutyric acid — nearly 3,000 times the concentration dolphins have in the non-bloom season.
“Those same brains also showed sweeping changes in gene expression and the appearance of protein-based structures characteristic of an Alzheimer’s-like disease: amyloid plaques,” IFLScience continued. “It’s not abnormal to see these plaques in dolphins – they’re considered to be a natural model of Alzheimer’s disease, as they develop these plaques with age – but this study suggests that harmful algal blooms may be accelerating the process.”
