Biomagnification — Science definition

The increasing concentration of a persistent pollutant in body tissues at each higher step of a food chain, so top predators carry the largest doses.

Where it is taught

In use

Biomagnification compares tissue concentrations between feeding levels.

Pollution

Questions using biomagnification

Problem 1

Biomagnification refers to the way that
  1. decomposers break pollutants down into harmless molecules
  2. a pollutant spreads evenly through the air until it is harmless
  3. a factory's scrubber removes pollutants before they leave the smokestack
  4. a persistent pollutant becomes more concentrated in organisms at each higher step of a food chain
Answer and explanation

a persistent pollutant becomes more concentrated in organisms at each higher step of a food chain

Because predators eat many contaminated prey and store rather than excrete the toxin, persistent pollutants grow more concentrated at each higher trophic level.

Problem 2

Within-organism accumulation differs from food-web magnificationWithin-organism accumulation differs from food-web magnificationWater / uptakeExposureOrganism storageBioaccumulationPredator dietPossiblebiomagnificationPersistent, bioavailable compounds can behave differently.Not every pollutant accumulates or magnifies through a food web.
Original process distinction; no specific chemical concentration or universal factor is asserted.
Interpret the supplied visual. Does a high concentration in one fish alone prove biomagnification?
Answer and explanation

No. It can show exposure/accumulation but a trophic comparison with compatible concentrations is needed for magnification.

Bioaccumulation is buildup within an organism when uptake exceeds elimination over time. Biomagnification is increasing concentration across trophic positions through dietary transfer under appropriate persistence, uptake and elimination conditions. The concepts are related but not identical. Some compounds do neither, and comparing different tissues or wet/dry mass bases can mislead. Specify the chemical, tissue, concentration basis and food-web evidence before asserting a universal higher-predator pattern.

No. It can show exposure/accumulation but a trophic comparison with compatible concentrations is needed for magnification.

Response criteria

  • Interpret labels, structures, axes, units and directions correctly.
  • Explain the physical or environmental relationship or mechanism.
  • Respect stated assumptions and distinguish observation from inference.

Problem 3

Explain the difference between bioaccumulation and biomagnification.
Answer and explanation

Bioaccumulation is the buildup of a persistent pollutant within a single organism over its lifetime, because it stores the toxin faster than it can get rid of it. Biomagnification is the increase in that pollutant's concentration from one trophic level to the next up a food chain, because each predator eats many contaminated prey. Bioaccumulation happens within an individual; biomagnification happens across a food chain.

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