Read the following statements and choose the correct option:
1. The introduction of invasive alien species can lead to the displacement of native species.
2. Water hyacinth (Eichhornia) is an invasive plant that disrupts the ecological balance in water bodies.
3. The African catfish (Clarias gariepinus) was introduced legally for aquaculture purposes.
4. The Nile perch’s introduction to Lake Victoria had no significant impact on the lake’s native fish species.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statements 1 and 2 are correct.
True. 1. The introduction of invasive alien species can lead to the displacement of native species. Some introduced species turn invasive and cause the decline or extinction of indigenous species.
True. 2. Water hyacinth (Eichhornia) is an invasive plant that disrupts the ecological balance in water bodies. The book names water hyacinth among the invasive weeds that damage the environment and threaten native species.
False. 3. The African catfish (Clarias gariepinus) was introduced legally for aquaculture purposes. Its introduction was illegal, and it threatens the native catfishes of our rivers.
False. 4. The Nile perch’s introduction to Lake Victoria had no significant impact on the lake’s native fish species. The Nile perch led to the extinction of more than 200 species of cichlid fish in the lake.
Statements 1 and 2 are correct.
NCERT Extract:
Loss of Biodiversity – “… (iii) Alien species invasions: When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species. The Nile perch introduced into Lake Victoria in east Africa led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake. You must be familiar with the environmental damage caused and threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eicchornia). The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.”