Biomagnification
The increase in pollutant concentration through successive trophic levels in food chains, causing apex predators to have highest concentrations.
Formula
Biomagnification Factor = [Concentration at trophic level n+1] / [Concentration at trophic level n]
Real World
PCB concentrations in the Great Lakes food web rise from 0.0025 ppm in phytoplankton to over 124 ppm in herring gulls — a roughly 50,000-fold increase across five trophic levels.
Exam Focus
Distinguish biomagnification (increasing concentration up food chain) from bioaccumulation (within one organism); confusing the two is a common exam error.
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