DDT was sprayed in a lake to regulate breeding of mosquitoes. How would it affect the trophic levels in the following food chain associated with a lake? Justify your answer.
Answer
● DDT being a non- biodegradable pesticide will enter the food chain from the first trophic level i.e. Plankton.
● Non – biodegradable pesticides accumulate progressively at each trophic level. This phenomenon is known as biological magnification.
● HAWK will have the highest level of pesticide.
Explanation-
Trophic Level means
Various steps in food chain where transfer of food or energy takes place
Each step in trophic level represents an organism
In the given question,
Plankton will be eaten by Small Fish which will be eaten by Large Fish who will be eaten by Hawk
So following are trophic levels
Hawk
(Fourth trophic level)
I
Large fish
(Third trophic level)
I
Small Fish
(Second trophic level)
I
Plankton
(First Trophic Level)
Aquatic Environment means
An ecosystem which is surrounded by water
It includes water bodies as well as aquatic plants and animals
It is not a part of trophic level
DDT is a non degradable pesticide which affects the health of plants as well as animals
Spraying of DDT in lake will be absorbed by plankton
(Plankton is a plant which is eaten by Small fish
Small fish is eaten by Large Fish who are eaten by Hawk)
These non degradable pesticides accumulate progressively at each trophic level
It is lowest at first trophic levels (plankton) and highest at last trophic level
Hence, there is Increase in concentration of harmful chemical substances at each trophic level is called biological magnification
This phenomena is called biological Magnification
