why is Concentration of toxins found to be more in the organisms occupying the highest trophic level in the food chain in a polluted water body? Explain with the help of a suitable example?
The phenomenon responsible for finding more concentration of toxins in the organisms occupying the highest trophic level in the food chain in a polluted water body is biological magnification. Biological magnification refers to the increase in the concentration of a toxicant at successive trophic levels. When the toxic substance or pollutant cannot be excreted or metabolised by an organism, it is passed on to the next trophic level. In this way, the concentration of the pollutant keeps increasing at each successive trophic level through biological magnification
For example, DDT (used as a pesticide, but toxic for animal life, especially birds, by thinning their egg shell) is biomagnified in successive trophic levels in food chain of polluted aquatic habitat. If the concentration of DDT in water is 0.003 ppb, it can ultimately reach 25 ppb in fish-eating birds, passing and magnifying through the various trophic levels of water such as zooplanktons, small fish and large fish.
For example, DDT (used as a pesticide, but toxic for animal life, especially birds, by thinning their egg shell) is biomagnified in successive trophic levels in food chain of polluted aquatic habitat. If the concentration of DDT in water is 0.003 ppb, it can ultimately reach 25 ppb in fish-eating birds, passing and magnifying through the various trophic levels of water such as zooplanktons, small fish and large fish.