What is "biomagnification"

n. (context biology English) The process, in an ecosystem, in which a higher concentration of a substance in an organism is obtained higher up the food chain.

Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of organisms at successively higher levels in a food chain. This increase can occur as a result of:

• Persistence – where the substance can't be broken down by environmental processes
• Food chain energetics – where the substance concentration increases progressively as it moves up a food chain
• Low or non-existent rate of internal degradation or excretion of the substance – often due to water-insolubility

Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. The substances become concentrated in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.

The following is an example showing how bio-magnification takes place in nature: An anchovy eats zoo-plankton that have tiny amounts of mercury that the zoo-plankton has picked up from the water throughout the anchovies lifespan. A tuna eats many of these anchovies over its life, accumulating the mercury in each of those anchovies into its body. If the mercury stunts the growth of the anchovies, that tuna is required to eat more little fish to stay alive. Because there are more little fish being eaten, the mercury content is magnified.