Question

Which of the following is also referred to as ‘Terror of Bengal’.
(a) Algal bloom
(b) Eichchornia crassipes
(c) Increased biochemical oxygen demand
(d) Eutrophication

Answer 1

Hint: There are some aquatic plants that grow profusely in water bodies. It deprives oxygen from water resulting in the death of fishes and other aquatic organisms. These are notable for their beautiful flowers and shape of leaves but gradually become a troublesome aquatic weed.

Complete answer:
-Water hyacinth or Eichchornia crassipes is known as ‘Terror of Bengal’.
-It was introduced in India because of its ornamental values, but it spread all over the water bodies in a very short period of time by vegetative propagation.
-It exhibits hydrophytic adaptations.
-They generally float so that leaves and flowers are held above water. It prevents them from rotting.
- They have special adaptations to withstand high temperature, pH, and even toxic water.
-It propagates at a very quick rate. It can double in just two weeks.
- It has a spongy and inflated leafstalk.
-They have fibrous roots. It provides a shelter for many small aquatic fishes and other invertebrates. Their roots are capable of absorbing impurities.

Additional information:
-They require high temperatures and become more invasive during summers.
-They prevent sunlight for underwater plants thus causing their death.
-Water hyacinth contains poisonous allergic lactones and other alkaloids.
-Due to their ability to deprive oxygen, the aquatic micro ecosystem does not get balanced. It also reduces fish diversity and phytoplankton productivity.

So the correct answer is Eichchornia crassipes.

Note:
There are physical, chemical, and biological methods to control or eradicate water hyacinth. Reducing nutrient content in the soil, cutting, the introduction of plant pathogens are some of the methods employed. Biological methods are the most effective methods to control such weeds.