Neurotoxic Bioaccumulation in Land Vertebrates

Question

Bioaccumulation and Biomagnification are common concerns in marine environments, with natural examples like Ciguatera being a well known example caused by an algae that grows on coral that is then concentrated in the bodies of predatory fish like barracudas.

My world building question is can such a thing occur on land, and can it occur with less steps in the food chain?

The scenario is as follows:

• There’s a poisonous plant that grows in abundance on an isolated continent.
• A large herbivore eats it and stores the fat soluble toxin in its body.
• The human settlers eat the herbivores because they’re quite tasty and are better than sea biscuits and failed crops.
• The human settlers then slowly go insane over the next few weeks before ultimately succumbing to constant seizures and organ failure.

Is this plausible? Is there some fundamental principle of ecology and toxicology that I’m missing? Any suggestions if it’s implausible?

NOTE: There are large predators that have even more of the toxin, to the point that settlers who eat it die within hours.

Answer 1

I don't see any reason not, specifically. I can't think of any cases of biomagnification in the terrestrial realm off the top of my head, but I bet there are some.

The reason you hear more about biomagification in aquatic ecosystems is that aquatic ecosystems tend to be four or five links long because most of the base of the food chain is plankton and most of the predators are cold-blooded. Food chains in the water tend to go:

phytoplankton->zooplankton->filter feeder->small predator (e.g., perch)->apex predator (shark, grouper)

On land most food chains are only three links long:

plant->herbivore->carnivore.

You do get more diversity on the smaller scale where you have predatory insects being eaten by birds being eaten by snakes and such, but with today's predominantly warm-blooded megafauna so much energy is lost due to their metabolism the ecosystem can't support many links. This ties back into biomagnification in that what makes biomagnification worse is the number of times biomass switches hands in the food chain. Apex aquatic predators like barracuda, swordfish, and the like are bad when it comes to sequestering heavy metals because the toxins in their biomass have been concentrated five or six times, and the parasites that feed on them like lamprey somehow manage to be worse (in some areas of high pollution sea lamprey meat has been described as looking and smelling like metal slag due to toxic metal concentration).