Question

Explain bioaccumulation and biomagnifications with examples.

Answer 1

Hint:
Bioaccumulation and biomagnification are two different processes that often happen in tandem with one another. Bioaccumulation is the process by which toxic substances enter the food chain by building up in individual organisms, while biomagnification is the process by which toxins are passed from one trophic level to another and thereby increase in concentration within a food chain.

Complete answer:
> Bioaccumulation: Bioaccumulation can be considered as the entry of a pollutant or toxic substance in the food chain. It is actually the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. It can occur in two main ways. One way is that an amount of the chemical substance coming into the living organism faster than the organism can break it down and use it. This means that more is going in than is coming out, therefore causing the chemical to accumulate in the organism.
The other main way by which bioaccumulation occurs is that the chemical coming into the living organism and the organism not being able to break it down or excrete it in one way or another. In these instances, the chemical continues to accumulate until it eventually becomes deadly to the living organism.
Example: Mercury is a chemical contaminant found in most water bodies. Phytoplankton and bacteria both feed on the mercury, which is fine for them. However, some species of small fish then eat the bacteria and phytoplankton and then get eaten by larger fish. The small and large fish both accumulate mercury in their bodies. Up to this point, it is bioaccumulation.
> Biomagnification: Biomagnification refers to the increase in concentration of a toxic substance at each successive trophic level after entering into the food chain. This usually occurs across the entire food chain and affects all of the organisms but animals present at higher trophic levels in the chain are more impacted.
Example: Pesticides such as DDT, is non biodegradable. It gets incorporated in the food chain and gets deposited in the tissues of the organisms.
When DDT enters into water bodies, it gets accumulated in the body of fishes and this is known as bioaccumulation. When these fishes are eaten by animals of higher trophic levels, concentration of DDT is increased at each successive trophic level and this is known as biomagnification.

Note:
Biological magnification specifically refers to increasing concentration of materials in each higher connecting link in the food chain. However, bioaccumulation examines the increased presence of a particular substance inside a single organism.