Question

The residents of Nanganallur and Adambakkam wanted to revive an environment park on

Adambakkam Eri. The lake needs to be desilted and deepened and a bund is to be formed for a

walkers’ path. Moreover, steps are to be taken to prevent the discharge of sewage through

storm water drains and the dumping of garbage on the lake bunds. The environmentalists say

that invasive species like water hyacinth have clogged this water body. Also, the discharge of

sewage in to the lake has resulted in the growth of unwanted plants. This is blocking the air-

water interface, thereby reducing the dissolved oxygen in the water killing a lot of fish. The

water bodies clogged by the invasive species also become a breeding ground for mosquitoes.

The State Government has been requested to expedite the works for this at the earliest.

Question 26:

When an alien species (plant or animal) that does not belong to an ecosystem is introduced, it

spreads and competes with the native plants for space and nutrients and becomes problematic

in the absence of natural enemies. These intruders are called invasive alien species.

What are the ill effects of an invasive species like water hyacinth?

i. Blockage of sunlight from reaching native aquatic plants.

ii. Starving the water of carbon dioxide

iii. Domination and phasing out of fish and other native species.

iv. Change in the water quality with respect to the dissolved oxygen and the water pH due

to release of CO2 .

v. Starving the water of oxygen.

vi. Desilting of the water body

vii. An increase in algae blooms, mosquito infestation due to dense matting and decreased

water flow​

Answer 1

Answer:

Explanation:

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