Question

The world is facing accelerated rates of species extinction largely due to human activities. Explain any three human activities responsible for accelerated rates of species extinction.

Answer 1

1. Habitat loss and fragmentation: 
   1. Unsustainable human activities, including mining, urbanisation, slash-and-burn agriculture, and deforestation, change or destroy the habitats of many different creatures.
   2. This causes the habitat to fragment into tiny fragments, which affects migratory animals' movement and reduces genetic exchange between populations, ultimately resulting in the decline of species.
   3. For example:
      1. The reduction of tropical rainforests has decreased from 14% to 6%. Thousands of hectares of rainforests are being lost within hours.
      2. The Amazon rain forest is being cleared for soy bean farming or to make way for cow pastures.
2. Over-exploitation:
   1. Many animal and plant species are now endangered or extinct as a result of human overexploitation and poaching.
   2. Due to overexploitation, many species have gone extinct, including the passenger pigeon and Stellar's sea cow.
3. Alien species invasions: 
   1. The introduction of non-native species into an ecosystem, whether accidental or intentional, has caused the decline or extinction of indigenous species. Invasive species can lead to the extinction of indigenous species.
   2. For example:
      1. More than 200 species of native fish and cichlid fish in Lake Victoria, East Africa, became extinct as a result of the introduction of the Nile Perch.
      2. Invasive plant species such as carrot grass (Parthenium), Lantana, and water hyacinth (Eichhornia) have adversely affected our indigenous flora.
      3. The native catfish in our rivers are in danger due to the illicit import of the African catfish (Clarias gariepinus) for aquaculture.