What is biomagnification what are its effects on the food chain?
Answer:
Biomagnification, also known as bioamplification, or biological magnification is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of:
* Food chain energetics
* Low (or nonexistent) rate of excretion/degradation of the substance.
It is an important concept in ecology, environmental science, and ecotoxicology: it says that the solution to certain types of pollution is not dilution, because food chains will concentrate the pollutant.
More at wiki - http://en.wikipedia.org/wiki/biomagnific...
http://www.marietta.edu/~biol/102/ecosys...
http://www.marietta.edu/~biol/102/2bioma...
http://www.greenfacts.org/glossary/abc/b...
http://toxics.usgs.gov/definitions/bioma...
When a pollutant like DDT assimilates in body of living organism (through processes like eating pollutant contaminated food) then the process is called bio-accumulation.
When through the processes of eating and being eaten the stored or accumulated pollutant rises up the food chain and increases in quantity in the process then it is called bio-magnification.
Eg: When DDT is used over crops as a pesticide, the plants accumulate it in their body--leaves, stem etc. This is bio-accumulation. When a pest like locust feeds on such crop it accumulates DDT in larger quantities since it eats more than one leaf. When a snake feeds on such pollutant infected frog it stores further more DDT since it feeds on many frogs. Likewise as we move up in the food chain the amount of pollutant stored in organisms in each trophic level increases. This is called BIO MAGNIFICATION.
Biomagnification, also known as bioamplification, or biological magnification is the increase in concentration of a substance, such as the pesticide DDT, that occurs in a food chain as a consequence of:
Food chain energetics
Low (or nonexistent) rate of excretion/degradation of the substance.
It is an important concept in ecology, environmental science, and ecotoxicology: it says that the solution to certain types of pollution is not dilution, because food chains will concentrate the pollutant.
Although sometimes used noninterchangeably with 'bioaccumulation,' an important distinction is drawn between the two. Bioaccumulation occurs within a trophic level, and is the increase in concentration of a substance in an individual's tissues due to uptake from food and sediments in an aquatic milieu. Bioconcentration is defined as occurring when uptake from the water is greater than excretion. (Landrum and Fisher, 1999). Thus bioconcentration and bioaccumulation occur within an organism, and biomagnification occurs across trophic (food chain) levels.
Lipid soluble (lipophilic) substances cannot be excreted in urine, a water-based medium, and so accumulate in fatty tissues of an organism if the organism lacks enzymes to degrade them. When eaten by another organism, fats are absorbed in the gut, carrying the substance, which then accumulates in the fats of the predator. Since at each level of the food chain there is a lot of energy loss, a predator must consume many prey, including all of their lipophilic substances.
For example, though mercury is only present in small amounts in seawater, it is absorbed by algae (generally as methylmercury). It is efficiently absorbed, but only very slowly excreted by organisms (Croteau et al, 2005). Bioaccumulation and biomagnification result in buildup in the adipose tissue of successive trophic levels: zooplankton, small nekton, larger fish etc. Anything which eats these fish also consumes the higher level of mercury the fish have accumulated. This process explains why predatory fish such as swordfish and sharks or birds like osprey and eagles have higher concentrations of mercury in their tissue than could be accounted for by direct exposure alone. For example, herring contains mercury at approximately 0.01 ppm and shark contains mercury at greater than 1 ppm (EPA 1997).
along with what the others have said already, it is also known as bioaccumulation.
it's a phenomena thru ...which pollutants like DDT &PCB[polychlorinatedbiphenyls] get accumulated in fat containing animal tissues in increasing conc* along a food chain. such pollutants can cause disruptions in animal repro*
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