Question

Write a critical note on biological magnification.

Write a critical note on the following:

Biological magnification

Answer 1

Many pesticides are used to protect crops from diseases and pests. Plants absorb these pesticides from the soil, along with water and minerals. Due to rain, these chemicals can also enter water sources and into the bodies of aquatic plants and animals. As a result, chemicals enter the food chain. Since these chemicals cannot be decomposed, they keep accumulating at each trophic level. The maximum concentration is accumulated at the top carnivore’s level. This increase in the concentration of pollutants or harmful chemicals, along with an increase in the trophic level, is called biological magnification. For example, high DDT concentrations were found in a pond. The producers (phytoplankton) were found to have a 0.04 ppm concentration of DDT. Since many types of phytoplankton were eaten by zooplankton (consumers), the concentration of DDT in the bodies of zooplankton was found to be 0.23 ppm. Small fish that feed on zooplankton accumulate more DDT in their bodies. Thus, large fish (top carnivores) that feed on several small fish have the highest concentration of DDT.

Biomagnification of DDT in an aquatic food chain