Question

Explain biomagnification of DDT in an aquatic food chain. How does it affect the bird population?

Answer 1

Biomagnification is the increase in the concentration of a toxin at successive trophic levels. The toxin gets accumulated because a toxic substance cannot be metabolised or excreted, and is thus passed on the next higher trophic level. In aquatic ecosystem the concentration of DDT increases at successive trophic levels. It is present in low amount in water and reaches a high concentration in fish-eating birds through biomagnification. Very high concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.