DDT contant in the water of a lake that supplies drinking water to the nearby villages, is found to be 0.003 ppm. The kingfishers of that area reported to have 2 ppm of DDT. Why has the concentration increased in these birds ? What harm will this cause to the bird population ? Name the phenomenon.

Explanation

This happens because a toxic substance accumlated by an organism can not be metabolised or exerted, and is thus passed on to next higher trophic level. This phenomenon is well-known for mercury and DDT. High concentration of DDT disturb calcium metabolism in birds, which causes thinning of agg shell and their premature breaking, eventually causing decline in bird populations . This phenomenon is called bio magnification .