The closure of both the recreational and commercial Dungeness crab fishery this year in response to very high levels of domoic acid (DA) in these animals is an expected outcome of the massive bloom that took place from May to late September along the coast of California (and all the way to Alaska). Full body loads of DA well exceed the regulatory limit of 20 parts per million (ppm), and unlike in past years, both the viscera (i.e. hepatopancreas, or “crab butter”) AND the flesh (e.g. crab legs) have high toxin loads, in some cases 10-20 times higher than the regulatory limit. How are the crabs acquiring DA? Past studies in Monterey Bay1 and Santa Barbara Channel2 found substantial transport of DA from the ocean surface to much deeper water, its persistence in sediments, and most importantly, its long-term (several months long) persistence in tissues of animals that feed at this sediment-water interface (i.e. “benthic” organisms), such as innkeeper worms, sea urchins, and various crustaceans. Dungeness and rock crabs are a central part of this benthic food web and will acquire DA by eating on smaller crustaceans and fish that are exposed to DA as they feed on detritus and algae on top of the bottom sediments. The end result is that even when a bloom is no longer taking place in surface water and DA is no longer detectable in the water, these bottom-dwelling animals can remain toxic for long periods, presumably until that pool of DA in the sediments is depleted. For some animals, like the innkeeper worm, DA may never entirely flush out of their bodies as the ecosystem moves from one seasonal Pseudo-nitzschia bloom to another. The big question on everyone’s mind is “how long will it take for the crabs to become non-toxic or for DA to fall below the regulatory limit?” No one has the answer to this, and it will most likely depend on exhausting the DA pool in the sediments that has built up over 5 months of a highly toxic bloom this spring and summer. The pool could be very large, and we do not have sampling data from the sediments to verify just how big. While the crabs will flush the toxin out after a week or so, if they are able to continually acquire it from their food supply, they will remain toxic.