biomagnifies

Biomagnifies refers to the ecological process by which the concentration of certain contaminants increases at higher trophic levels in a food chain. When a substance biomagnifies, organisms higher in the chain accumulate greater concentrations through predation and dietary intake, producing higher body burdens than organisms at lower levels. This phenomenon occurs even when environmental concentrations remain constant because the substance is persistent, bioavailable, and not readily excreted or metabolized.

Biomagnification is distinct from bioaccumulation within a single organism; it describes the transfer and amplification of a contaminant across several species in a food web. Substances that biomagnify are typically lipophilic, resistant to degradation, and have long biological half-lives. Because predators consume many prey items over time, small daily intakes can accumulate to large concentrations in tissue, especially in fatty tissues.

Common examples include methylmercury in aquatic ecosystems, and organochlorine compounds such as DDT and PCBs in birds, fish, and marine mammals. The ecological and health implications include adverse effects on reproduction, development, and nervous system function in wildlife, and potential risks to humans who consume contaminated seafood or wildlife.

Scientists measure biomagnification using metrics such as trophic magnification factors or biomagnification factors, derived from concentrations across species and normalized for lipid content. Factors that influence the magnitude of biomagnification include chemical properties, food-chain length, feeding rates, and ecosystem structure. Management approaches focus on reducing releases of persistent pollutants and limiting exposure at higher trophic levels.