Continuing with our previous post, “toxics vs. toxins”, Orca Action Month will be focusing today on bioaccumulation vs. biomagnification, and the difference between the two.
Read the full story below, written by Orca Month designer Rosemary Connelli.
Photo: Bioaccumulation of toxics in Southern Resident Orcas ©Defenders of Wildlife.
Bioaccumulation
Bioaccumulation occurs when pollutants enter the food web and build up in organisms over time. For example, a fish living in a polluted lake will absorb that pollution from the water and the chemicals will accumulate in the fish’s tissue.
Biomagnification
Biomagnification occurs when pollutants move up the food chain and become increasingly concentrated in organisms at higher trophic levels. Top predators like Southern Residents eat large amounts of prey, many of which have already accumulated pollutants. The more contaminated prey an orca eats, the more pollutants it will have in its body.
In both processes, chemical concentration increases because organisms cannot break down or excrete these persistent substances as quickly as they are absorbed.
To also learn more about contaminants of concern, check out Defenders of Wildlife’s article “Clean Water, Healthy Futures: Why Saving Orcas Means Saving Us”: https://defenders.org/blog/2024/04/clean-water-healthy-futures-why-saving-orcas-means-saving-us
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