Top predators in the Arctic are known to accumulate vitamin A, often to levels that are toxic for human consumption. A 2012 study by Senoo, Imai, et al. found that the livers of several predator species in the Arctic showed much higher levels of vitamin A than other Arctic species or closely related continental species, with no symptoms of hypervitaminosis A.
Why is it that these species accumulate vitamin A? Does this have something to do with the food sources available in the Arctic as opposed to the mainland? Or are there physiological reasons why Arctic predators would tend to accumulate vitamin A rather than breaking it down or otherwise eliminating it?