Unexpected effects from low doses of toxins from harmful algal blooms


remote sensing based image of 2015 algal bloom from NOAA’s climate.gov

Johanna Eurich reports from the Alaska Marine Science Symposium 1/23-26/2017

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 oceans and stranded on beaches last year… some researches suspected that toxic algae blooms might have been responsible. It would not be the first time such a thing may have occurred according to Nicholas Pyenson (PIE-en-son), a paleo-biologist and curator of the Smithsonian Natural History Museum’s fossil marine mammal collection. He points to a huge graveyard of 900-year-old fossil whales recently discovered in Chile.

———————————————————————toxin 1.

:18 “Something else about this site; there’s not just whales there, there’s dolphins, early seals. That’s what we call a multispecies stranding event. So this happened many times. Harmful algal blooms is the only explanation that really explains why we have the profile of death that we see at this site.”

. —————————————————————————————–

Pyenson says the red halo of iron they found around the bones is the telltale sign of toxic algae blooms.

——————————————————————————————–Toxin 2     :09  “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.”


That’s the same Red Tide that closes clam beaches today when it occurs in Alaska …as it has done more frequently in our warming seas.

It’s not just whales that are suffering. Kathi Lefebvre (leh-FAIV) with the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center says marine mammals like sea lions are being found with the beginnings of seizures from a harmful algae blooms associated with Red Tide.

————————————————————————————-toxin 3

:10 “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.”


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.

——————————————————————————————-toxin 4       :13 “Pacific Northwest recreational and tribal communities subsistence harvest razor clams, which we know retain low level of toxin below the regulatory limit for up to a year or more after the bloom. 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.

—————————————————————————————toxin 5

:13  “Exposed mice simply did not learn. This big of an effect just completely shocked us cause we weren’t really… you know 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 human 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 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.




  1. Ceal Smith says:

    This is good work. Got to get you on board with the AK Climate and Energy Network…

  2. whoah this blog is excellent i love reading your posts.
    Keep up the great work! You realize, a lot of persons are searching around
    for this info, you could aid them greatly.

Leave a Reply

Your email address will not be published. Required fields are marked *