Invasive Alien Species
Definition and Nature
- Invasive alien species are non-native plants, animals, pathogens, or other organisms that have been introduced—intentionally or accidentally—into ecosystems where they do not naturally occur. These species often spread rapidly and can cause significant ecological, economic, or health-related harm. Unlike native species, they often lack natural predators or competitors in the new environment, allowing them to outcompete, prey upon, or infect native species, leading to their decline or extinction.
Impact on Biodiversity and Ecosystems
- The most serious consequence of invasive alien species is their adverse impact on native biodiversity. They disrupt ecosystems by altering food chains, changing nutrient cycles, or outcompeting native species for resources. In many cases, they introduce new pathogens or act as carriers of disease, further endangering local flora and fauna. As a result, entire ecosystem functions may be destabilized. According to the Convention on Biological Diversity (CBD), nearly 40% of documented animal extinctions since the 17th century have been directly linked to invasive species.
Wider Socio-Economic and Developmental Impact
- Beyond ecology, invasive alien species impose a heavy socio-economic burden, particularly in developing countries. They affect agriculture, forestry, fisheries, and water systems, thereby threatening the livelihoods of rural and indigenous communities. Their presence leads to reduced crop yields, forest degradation, loss of native fish stocks, and increased costs of control and eradication. Furthermore, they can worsen poverty and food insecurity.
Role of Human Activity and Climate Change
- The spread of invasive species is closely linked to human activities such as global trade, travel, habitat destruction, and land-use change. These disturbances weaken natural barriers and create favorable conditions for invasive species to establish themselves. Additionally, climate change amplifies their impact by enabling them to thrive in new regions and by increasing the vulnerability of native species already under environmental stress.