Bioaccumulation and biomagnification are two words that can easily be confused as they are both used to describe the increase in concentration of a pollutant within living organisms. The main difference between the two is the stage at which this build up occurs. In bioaccumulation, the toxicant comes directly to an individual from its surrounding environment, and gradually increases within this individual overtime. In biomagnification, the increase happens between trophic levels and the toxicant is amplified as it makes its way up the food chain.

Photo Credit: National Geographic Society

For example, a small-bodied fish, like a Common Shiner, is exposed to the insecticide DDT. As this shiner continually feeds and breathes within this contaminated environment, the DDT bioaccumulates. If a Smallmouth Bass feeds on this shiner, as well as other organisms that have absorbed this chemical, the concentration will be higher in the bass than it was in the shiner. Likewise, if this bass is eaten by an Osprey, the Osprey will have an even higher concentration of DDT than the bass, as it is likely consuming other contaminated fish. The Osprey is then the most impacted by DDT and its effects since the substance has biomagnified.