Describe Biomagnification of DDT in an aquatic food chain.

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels due to accumulation of  a toxic substance by an organism. The toxic substance cannot be metabolised or excreted, is thus passed on to the next higher trophic level along a food chain. one such example is that of of DDT which increases at successive trophic levels.

if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately can reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification. High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing decline in bird populations.

Biomagnification
Biomagnification