what is Biomagnification?

Biomagnification (or bioaccumulation) refers to the ability of living organisms to accumulate certain chemicals to a concentration larger than that occurring in their inorganic, non-living environment, or in the case of animals, in the food that they eat. Organisms accumulate any chemical needed for their nutrition read less

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. read less

Biomagnification is the amplification of levels of pollutants as we move up the trophic levels of the food chain. Pollutants which cannot be broken down and hence cannot be excreted by organisms are ingested by smaller organisms, these organisms are then consumed by slightly bigger organism above the food chain and so on. The accumulation increases as we go up the chain because of the increasing persistence of the pollutants and higher energy requirements at higher levels. The main two categories of pollutants are: a. Persistent organic pollutants (POPs), which are novel organic materials like DDT, Hexachlorobenzene etc b. Pure metals like Mercury. The case of Minamata disease is a perfect example of biomagnification, the mercury in the industrial wastes are consumed by small fishes, a large no of small fishes are consumed by an individual big fish and then the particular fish is consumed by a bird or humans. read less