From Great Lakes Wiki
Biomagnification is the process by which concentration of a pollutant increases from one link in a food chain to another. For example, in an ecosystem with pollutants leaking into the water supply, pollution will initially accumulate in aquatic species. As larger aquatic animals eat smaller ones, they will take in the pollutants, making themselves more saturated. When an even larger predator, such as a hawk, eats many fish, it will then take in more pollutants than the lower parts of the food chain. If it eats many fish that were able to survive with relatively manageable amounts of pollution, it may end up taking in more pollutants than it can handle.
