Evidence Suggests Harmful Algae Blooms Impact Species From Humans To Whales
There is growing evidence that harmful algae blooms have widespread health impacts on everything from humans to whales.
When fin whales were found floating dead in Alaska's oceans and stranded on beaches last year, some researchers suspected that toxic algae blooms might have been responsible. According to Nicholas Pyenson, a paleo-biologist and curator of the Smithsonian Natural History Museum's fossil marine mammal collection, it would not be the first time such a thing may have occurred. He points to a huge graveyard of 900-year-old fossilized whales recently discovered in Chile.
"Something else about this site, there's not just whales there; there's dolphins, early seals. That's what we call a multi-species stranding event," Pyenson said. "So this happened many times. Harmful algal blooms are the only explanation that really explains why we have the profile of death that we see at this site."
Pyenson says that the red halo of iron they found around the bones is a telltale sign of toxic algae blooms.
"So we do have a candidate; a smoking gun. Could it have been domoic acid? Sure, but dinoflagellates Red Tide is, I think, probably the most likely explanation," he said.
That's the same Red Tide that closes clam beaches today when it occurs in Alaska, something that has been happening more frequently as a result of our warming seas.
It's not just whales that are suffering. Kathi Lefebvre with the National Oceanic and Atmospheric Administration's Northwest Fisheries Science Center says that marine mammals, like sea lions, are being found with the beginnings of seizures from harmful algae blooms associated with Red Tide.
"You may or may not know, but on the central California coast we get dozens to hundreds of sea lions each year coming onto beaches, having seizures, and suffering from domoic acid poisoning," Lefebvre said.
NOAA scientists found evidence of memory loss and excitability in the sea lions that did not die from that exposure. That led them to wonder if the same thing was happening to humans who consume things like razor clams.
"Pacific Northwest recreational and tribal communities subsistence harvest razor clams, which we know retain low levels of toxins below the regulatory limit for up to a year or more after the bloom," Lefebvre said. "So that we know that populations are exposed to that."
Lefebvre and her colleagues exposed laboratory mice to low levels of domoic acid and trained them to run through mazes. At first they saw no effects, but after six months the change was striking.
"Exposed mice simply did not learn, Lefebvre said. "This big of an effect just completely shocked us. Doing chronic exposures is really risky, because a lot of times you don't see something, so this was a pretty dramatic effect; way more than we had expected."
More study is needed to understand the effects on humans, but Lefebre points out that existing standards are based on one-time high exposures that can cause seizures and permanent brain damage. The good news is that the kind of effects showing up in laboratory mice from long term low exposure can be reversible.
How does this relate to beached whales? Even if the exposure to domoic acid wasn't high enough to kill them, memory loss could have still made it tough to navigate.