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.

The use of DDT (dichlorodiphenyltrichloroethane) to control mosquito breeding in a lake can have profound effects on the trophic levels in the associated food chain. DDT is a pesticide that can bioaccumulate and biomagnify through food chains, impacting various organisms.

Let’s analyze the potential effects on each trophic level in the given food chain:

1. Plankton: DDT can enter the aquatic environment and affect plankton, which are primary producers. Plankton may absorb DDT from the water, leading to changes in their populations.
2. Small Fish: Small fish consume plankton and may accumulate DDT as they feed. The bioaccumulation of DDT in smaller organisms can lead to higher concentrations in organisms at higher trophic levels.
3.Large Fish: Large fish that prey on smaller fish can accumulate even higher levels of DDT due to biomagnification. DDT is known to persist in fatty tissues, and as larger predators consume numerous smaller organisms, the concentration of DDT can increase significantly.
4. Hawk: If the lake supports a population of fish that are contaminated with DDT, hawks (or other birds of prey) that feed on these fish may be exposed to high levels of the pesticide. Birds, especially raptors, can be particularly sensitive to DDT and its breakdown products.
5. Aquatic Environment: DDT can have detrimental effects on the overall aquatic environment. It can disrupt the balance of the ecosystem by affecting non-target organisms and reducing biodiversity. The long-term use of DDT can have cascading effects on various trophic levels, potentially leading to imbalances in the ecosystem.

Justification:
• Bioaccumulation: DDT tends to accumulate in the fatty tissues of organisms. As smaller organisms with lower trophic levels absorb DDT, the concentration increases in their tissues.
• Biomagnification: The process of biomagnification occurs as DDT moves up the food chain. Predators at higher trophic levels accumulate higher concentrations of the pesticide because they consume multiple contaminated organisms.
• Impact on Birds of Prey: DDT is notorious for its role in thinning eggshells of birds, particularly raptors like hawks. This thinning can lead to reproductive failures and population decline in these species.

In summary, the use of DDT in a lake can have far-reaching consequences on the trophic levels, potentially disrupting the balance of the ecosystem and posing risks to the health of organisms at higher trophic levels, especially birds of prey.