Question

Which is not a bioindicator of water pollution?
A) Blood worms
B) Stoneflies
C) Sewage fungus
D) Sludge worms

Answer 1

Hint:Let us first understand what is meant by water pollution and bioindicators. The process of contamination of water bodies like lakes, rivers etc as a result of human activity is known as water pollution. The organisms that represent the level of pollution are called bioindicators. Example: microbes, planktons, animals and plants.

Complete answer:
>Naturally occurring bioindicators play a predominant role in evaluating health of the environment.
>Sewage worms, blood worms and sludge worms are the bioindicators of water pollution.
> Sludge worm and bloodworm are commonly found near the sewe outlet which indicates the presences of sewage fungus and other organic matters.
>They can live in water bodies with low oxygen level.
>Stoneflies are the hemimetabolous insects, they are found in clean and running water bodies they cannot live in polluted water.

Additional information: Stoneflies are the type of aquatic insects. The immature ones (nymphs) are found in clean and flowing rivers, streams and springs. They generally creep under submerged objects or stones. Some of the species feed on algae, plants and organic matter. And few species are predators that feed on bugs. In cold mountain streams, they are an important source of food for some fishes. They are extremely sensitive to water pollution and act as biological indicators of water purity.

Therefore the correct answer option is (b) stoneflies.

Note:Sludge worms are a source of food for tropical fish. Bloodworm is the red coloured aquatic earthworm.It has a large supply of hemoglobin and stores the dissolved oxygen which is analogous to the human blood system. It is one of the primary sources of the aquatic food chain because almost all flesh eating fishes consume these worms.