8 Major Threats to Biodiversity and Ecosystem

2. Introduction of non-native species

According to some estimates, “introduced species are a greater threat to native biodiversity than pollution, harvest, and disease combined.” Moreover, the establishment of alien species creates significant economic costs. In the USA, 137 billion dollars is lost per year due to damage that invasive species cause in agriculture, forestry and fisheries.

People have been introducing non-native species to new habitats without causing serious problems for thousands of years. Consider only flowers and trees that we plant in our gardens. However, in some cases the introduction of alien species can seriously harm ecosystems. For instance, in 1940s North American beavers were brought to Argentina to start development of fur industry. The animal, whose population has reached 100.000, destroyed 40 million acres of forest. Other examples show that invasive species take away natural resources from native animals. Zebra mussel that was accidentally brought from Russia into the USA, and whose population has rapidly increased, have almost destroyed the population of native mussels in Great Lakes.

Sometimes, species are brought to new habitat to serve as a natural predator. For instance, mongooses were introduced to island Mljet to destroy snakes. Since there are no animals that feed on mongooses on Mljet, mongoose population went up, disturbing islands ecosystem and causing problems to locals. Finally, cross breeding between alien and native species lead to the extinction of domestic species because their gene pools change to become those of alien species.