Biomagnification

Biomagnification, also known
as bioamplification or biological magnification, is
any concentration of a toxin, such as pesticides, in
the tissues of tolerant organisms at successively
higher levels in a food chain.

1. Prepared by: Dewaka Poudel Environmental Biotechnology 7 th semester Submitted to: Astha Shakya Biomagnification

2. What is Biomagnification ? Biomagnification:Causes Example, substance that biomagnify Difference between: Biomagnification , Bioaccumulation and Bioconcentration Effect of Biomagnification

3. Biomagnification , also known as  bioamplification  or  biological magnification , is any concentration of a toxin, such as pesticides, in the  tissues  of tolerant organisms at successively higher levels in a  food chain .

4. This increase can occur as a result of: Persistence – where the substance cannot be broken down by environmental processes Food chain   energetics  – where the substance's concentration increases progressively as it moves up a food chain Low or non-existent rate of internal degradation or excretion of the substance – mainly due to water-insolubility

5. Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals work their way into lakes, rivers and the ocean, and then move up the food chain in progressively greater concentrations as they are incorporated into the diet of aquatic organisms such as  zooplankton , which in turn are eaten perhaps by fish, which then may be eaten by bigger fish, large birds, animals, or humans. The substances become increasingly 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. Biomagnification of toxins in the food chain of a terrestrial environment. The dots represent the organic molecules present in each trophic level. The crosses represent the mercury present in each trophic level. While dots remain relatively constant in each individual, the concentration of crosses become greater in each preceding trophic level. Biomagnification : An increase of toxin concentration as the food chain moves up to higher levels. Organisms at the top have a higher tissue concentration of toxins and pollutants than lower levels. The concentration system is due to persistence of the toxins, food chain energetics, and low rate of internal degradation or excretion of the substance.Trophic level I represents the primary producers. Trophic level II represents the primary consumers. Trophic level III represents the secondary consumers. Trophic level IV represents the tertiary consumers .

6. Causes of Biomagnification 1. Products Used in Agriculture: Chemical used in the agriculture sector is highly toxic and plays a pivotal part in biomagnification . Examples of such chemicals are various pesticides, herbicides, fungicides, and different inorganic fertilizers. Ultimately these chemicals penetrate the soil and then are carried to rivers and oceans via surface runoff. As a result, they enhance the biomagnification definition of causing harm to an entire food chain.   2. Industrial Activities: Toxic by-products released by various industries are a significant cause of biomagnification . Additionally, the gas emission by them pollutes the air and harms the ecosystem even further.   3. Organic Contaminants: Organic substances like manures and biosolids contain essential nutrients such as carbon, nitrogen, and phosphorus. Plants primarily use these. However, the industrial use of these substances causes biomagnification .   4. Mining: Mining produces by-products like copper, cobalt, zinc, lead and several other toxic chemicals. These substances are then deposited in soil and water resources and subsequently contaminate them.

7. Substances that biomagnify : There are two main groups of substances that biomagnify . Both are lipophilic and not easily degraded. Novel organic substances are not easily degraded because organisms lack previous exposure and have thus not  evolved  specific detoxification and excretion mechanisms, as there has been no selection pressure from them. These substances are consequently known as " persistent organic pollutants " or POPs. Metals are not degradable because they are elements. Organisms, particularly those subject to naturally high levels of exposure to metals, have mechanisms to sequester and excrete metals. Problems arise when organisms are exposed to higher concentrations than usual, which they cannot excrete rapidly enough to prevent damage. Some persistent  heavy metals  are especially dangerous and harmful to the organism's reproductive system. Novel organic substances : DDT  (dichlorodiphenyltrichloroethane) Hexachlorobenzene  (HCB) PCBs  (polychlorinated biphenyls) Toxaphene Monomethylmercury

8. A real-life example of biomagnification is – When a marsh is sprayed to control mosquitoes, it releases a trace amount of DDT. When mixed with water, it accumulates in the cell of various aquatic organisms. Once feeders up the food chain, such as clams and fishes, eat these organisms, they consume that DDT. Moreover, the concentration of DDT is ten times greater compared to the previous stage. This concentration of DDT moves up the food chain from one tropic level to another. For instance, if a seagull consumes one such fish, it will accumulate more DDT. According to studies, there was a 1000 times increase in the concentration of DDT in phytoplankton as compared to the concentration in water, 13 times higher in zooplankton as compared to phytoplankton, around 40 times higher in different fishes as compared to zooplankton and 25 times higher in fish-eating birds compared to fishes. DDT affects the calcium metabolism of birds and results in the thinning of eggshells. During the 1940s and 1950s, DDT was extensively used to decrease the mosquito population and this led to a rapid decline in the bird population. Another prominent biological magnification example is the presence of mercury in various predatory fishes. Fishes like swordfish, shark, tuna, orange roughy , king mackerel, etc., contain a higher level of toxic mercury than smaller fishes.

9. Effects of Biomagnification A significant effect of biological magnification is noted on human health. For instance, in recent years, a large number of individuals who have consumed seafood regularly have been diagnosed with cancer. The reason behind such a phenomenon is the presence of mercury. Other noted biomagnification effects are reproduction and development of all animals, destruction of coral reefs, and most significant disruption in the natural food chain and the ecosystem.

10. References : Silvy , Nova J., ed. (2012). The Wildlife Techniques Manual: Research. Vol. 1 (7th ed.). Baltimore, Maryland: The Johns Hopkins University Press. pp. 154–155.  ISBN   978-1-4214-0159-1 . ^  Landrum, PF and SW Fisher, 1999. Influence of lipids on the bioaccumulation and trophic transfer of organic contaminants in aquatic organisms. Chapter 9 in MT Arts and BC Wainman . Lipids in fresh water ecosystems. Springer Verlag , New York. ^   Croteau , M., S. N. Luoma , and A. R Stewart. 2005. Trophic transfer of metals along freshwater food webs: Evidence of cadmium biomagnification in nature. Limnol . Oceanogr . 50 (5): 1511-1519. ^  EPA (U.S. Environmental Protection Agency). 1997. Mercury Study Report to Congress. Vol. IV: An Assessment of Exposure to Mercury in the United States . EPA-452/R-97-006. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards and Office of Research and Development. ^   "DDT Ban Takes Effect" .  United States Environmental Protection Agency . 1972-12-31. Archived from  the original  on 2014-08-12. Retrieved 2014-08-10. ^   Suedel , B.C., Boraczek , J.A., Peddicord , R.K., Clifford, P.A. and Dillon, T.M., 1994. Trophic transfer and biomagnification potential of contaminants in  aquatic ecosystems . Reviews of Environmental Contamination and Toxicology 136: 21–89. ^  Gray, J.S., 2002. Biomagnification in marine systems: the perspective of an ecologist. Mar. Pollut . Bull. 45: 46–52.

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