Question

Introduction of some alien species causes biodiversity loss. Justify the statement with an example.

Answer 1

Hint:- New species entering a geographical region are called exotic or alien or non-native species. Alien species, when introduced unintentionally or deliberately for whatever purpose, may cause the disappearance of native or indigenous species through changed biotic interactions.

Complete Answer:-- Nile perch, a species of freshwater fish is native to the Congo, Nile, Senegal, Niger, and other river basins.
- It is a fish of considerable economic and food-security importance in East Africa.
- It was introduced into Lake Victoria in the 1950s to uplift the fishing industry due to its economic and food-related significance. An economic boom resulted due to the introduction of the Nile perch in Lake Victoria.
- Although, being predatory, it killed and eliminated an ecologically unique assemblage of over 200 species of cichlid fish that were endemic to this freshwater aquatic system.
Additional information:
Other examples of alien species are as follows:
1. Carrot grass (Parthenium) is a weed that came into India as a contaminant with imported wheat. It inhabited all open areas, putting an end to a number of species of herbs and shrubs.
2. Lantana is a straggling shrub of tropical America which got introduced in India accidentally. It became a serious weed recently and exterminated many species in forests.
3. Water hyacinth (Eichhornia) was introduced by Europeans in India. It has clogged water bodies including wetlands at many places resulting in the death of several aquatic plants and animals.

Note:- -Exotic species have the maximum harmful impact on island ecosystems because of the small size and the small number of species. Therefore, islands bear much of the world’s endangered biodiversity.
- Due to the recent illegal introduction of Clarias gariepinus in indigenous aquaculture imposed a threat on native river catfish.