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Biomagnification - 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: Although sometimes used interchangeably with ' bioaccumulation,' an important distinction is drawn between the two, and with bioconcentration, it is also important to distinct between sustainable development and overexploitation in biomagnification. Thus bioconcentration and bioaccumulation occur within an organism, and biomagnification occurs across trophic (food chain) levels. Lipid, ( lipophilic) or fat soluble substances cannot be diluted, broken down, or 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. Several things must be true of a substance for biological magnification to occur. The substance must be able to be absorbed at some point in the food chain, or else it would not be able to be magnified. It must not be broken down easily by the environment, as this would remove it from the food chain. It must be difficult for organisms to break down or safely digest it, as digestion would also prevent it from being absorbed by organisms higher in the food chain. While biological magnification can technically happen with any substance that meets these criteria, it is usually studied because of the magnification of harmful substances such as fertilizers, pesticides, and heavy metals. Often, such substances accumulate in an organism's fat cells, as they can not break dissolve in water and exit the body through the urine. When an organism higher in the food chain consumes a creature lower in the food chain, it absorbs fats in its gut. With these fats come the substances previously taken in by the other organism and all of the harmful effects these substances may carry with them. Many plants, aquatic and terrestrial, are prone to absorbing a variety of substances because they often lack the means to effectively digest them. Causes of Biological Magnification: 1. The production and release of the persistent organic chemical compounds in the environment. 2. Lipophilic character of the pollutant, causing it to be water insoluble and thus less degradable. Mechanism of Biological Magnification: Some organic chemical compounds which have slower rates of degradation (generally known as Xenobiotics) like DDT, PCBs, DDE when are released into the environment, their minute dissolved amounts get partitioned from the surrounding water into the lipids of the living microorganisms. When these microorganism are ingested by the organism of other higher trophic level organisms, the same concentration of these non degradable pollutants are transferred to this next trophic level as it is. So, its concentration as a result increases by an order of magnitude. This thing is goes on as the food chain succeeds further. Ultimately the Apex level i.e the Top level of food chain receives a huge amount of this pollutant. If we compare its concentration within the living cell to its concentration in the environment, we can see the concentration in the cells is actually 104 to 106 times more to that of in the environment.

Steps Taken to Prevent the Biological Maginification: It is a matter of concern, as this huge concentration of chemicals and pesticides inside the living system is dangerous for the health of the ecosystem and all its biotic components. These substances may cause death or invigorating effect on the affected organism. • As the severity of the matter was realized it led to the ban on the use of DDT in United States and the other developed countries. • The use of various environmental and biotechnological approaches to clean up the xenobiotic pollutants has been started. They are like detoxification, immobilization, composting, water treatment plans, use of recombinant microorganism for the degradation of xenobiotics etc.

Biomagnification of Contaminants Biomagnification. It's the word scientists use to explain why animals that eat other animals have higher levels of contaminants than animals that eat plants. Some contaminants are persistent - once they are in the animal's body, they stay there for a long time. So when smaller animals are eaten by bigger animals, all the contaminants stored in the smaller animals are then passed on to the bigger animal. The result of biomagnification is that animals at the "top" of their food chain have higher contaminant levels than animals at the "bottom." In the example below, the tiny drifting plants and animals will have much lower levels of contaminants than beluga. Example of Contaminants Reaching at Higher Trophic Levels through Biomagnification • Mercury in traditional foods

Human activities, such as making paper, building dams and burning fuel, have increased the amount of mercury in water, air and soil. In high doses, mercury is toxic to living things, causing damage to the brain and nerves. Mercury biomagnifies. This means there is more in animals with longer food chains. For example, seals have more mercury than cod. Loche, pike and lake trout have more mercury than whitefish. Loons have more mercury than geese or ptarmigan. Mercury is usually higher in fish than in land animals. • PCBs in Traditional Food

PCBs is short for PolyChlorinated Biphenyls. They are a type of organochlorine that was commonly used in electrical transformers. Very low levels of PCBs are found in water and soil; higher levels are found in animals. Because of their chemical nature, PCBs do not break down easily and so are passed up the food chain when a small animal is eaten by a larger one. PCBs have been measured in many animals across the North. They biomagnify. This means there will be more PCBs in animals high on the food chain. They are highest in fatty tissue. This means blubber and fat will have more PCBs than muscle, skin or organs.

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