Biological magnification is characterized by the concentration of toxic substances increasing within each of the food chain's successive links. The organisms on the lower levels of the food chain accumulate smaller amounts than organisms on the higher levels of the food chain.
During the process of biological magnification, heavy metals or pesticide travel up the food chain, get into lakes and rivers, and fish and other aquatic organisms eat them. Organisms on higher levels of the food chain, such as bears, large birds and humans, eat the fish and aquatic organisms. This results in the toxic substances moving up the food chain.