Tag: bioaccumulation and biomagnification

Biological magnification is the process of increasing concentration of the toxic substances in the living organism as they go up the food chain.

Biomagnification is the process where the concentration of toxic compounds increases in the body of the organisms through the food chain. The organisms at the higher trophic level will have more concentration of the compounds. Here, fishes are at the highest trophic level, so they will accumulate maximum amount of pesticides. So, the correct answer is 'Fishes'.

Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. Biomagnification process occurs when certain toxic chemicals and pollutants such as heavy metals, pesticides or polychlorinated biphenyls (PCBs) compounds go up the food chain by working their way through the environment and into the soil or the water systems after which they are eaten by aquatic animals or plants. Biomagnification occurs in the higher trophic levels of the food chain/web , where exposure to chemicals takes place mostly through food consumption rather than water uptake. Spraying a marsh to control mosquitoes will cause trace amounts of DDT to accumulate in the cells of microscopic aquatic organisms causing accumulation which cannot be metabolized.

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. 

A few toxic substances, often present in industrial wastewaters, can undergo biological magnification in the aquatic food chain. Biomagnification refers to increase in the concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. This phenomenon is well known for mercury and DDT. The concentration of DDT is increased  at successive trophic levels. For example, if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification. 

In India, prolonged use of 0.02-13 ppm of DDT (pesticide) can be detected in the body fat of the people. Most toxic pollutants such as pesticides do not degrade easily and therefore accumulate within the body of an organism specially in fat deposited portion. This process is known as biochemical concentration.

There are pesticides which have been detected in the aerated soft drinks by the researchers. These pesticides are known to accumulate within the tissues of the body. The permissible limit of pesticides in drinking water is 0.02 ppm. The accumulation of the pesticides may result in interference in the metabolic activities of the body. There are certain pesticides which are toxic and accumulation might degrade the tissues. 

Dichlorodiphenyltrichloroethane (DDT) is chemically an organochlorine that was used an insecticide. It is a stable compound that shows high solubility in the fatty tissues. When it is released in the water via the agricultural field surface run-off, it is ingested by the aquatic organisms like phytoplankton that are main producers in an aquatic food chain. From these, DDT continues rising up the food chain. Because successive consumers at the successive trophic level consume more food, it accumulates at the higher trophic level in greater amounts. This is called biomagnification. Sea/gulls and birds are the top consumers in an aquatic food chain, they will show the highest accumulation.