Question

A fish, Nile Perch, introduced into Lake Victoria in East-Africa led to extinction of chichilid fishes in the lake. This is example for

• A. Fragmentation
• B. Over exploitation
• C. Coextinctions
• D. Invasion of alien species

Answer 1

Answer: (D)

When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive and cause decline or extinction of indigenous species. Such species are also called exotic or introduced species. Examples:-

A) 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.

B) The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.

So, the correct answer is 'Invasion of alien species'.