Globalization has successfully increased the amount of trade, transport and tourism around the globe; however, it also facilitates the introduction and spread of non-native species. These alien species are intruders that are not indigenous to a particular ecosystem. Successful alien species become invasive by out-competing native organisms for food and habitat, causing harms to the local ecosystem. Invasive species are believed to be one of the leading threats to native wildlife. They also adversely affect people’s health and the economy standing behind the ecosystem. Many countries have invasive species problem, including but not limited to United States, United Kingdom, Australia, South Africa, India and Brazil. The problem of invasive species is urgent because the economic and environmental impacts are severe.
Causes of Invasive Species
There is a common misunderstanding that invasive species have to come from another country. In fact, an invasive species does not have to be a “foreigner”. For example, lake trout, which are native to the Great Lakes, are considered to be an invasive species in Yellowstone Lake because of their threat to indigenous cutthroat trout. Normally, an ecosystem has many checks and balances that limit the population growth of any one particular species. The correct number of carnivores, herbivores, parasites, and bacteria together create a complicated yet balanced web of life. Every species in this web need to fight for its own food source, living space and survival. However, with the introduction of non-native species, the checks and balances are broken. In many cases, there is no existing predator in the invaded ecosystem to prevent the alien species from expanding. Therefore, they survive, reproduce and grow huge in numbers that ultimately take over resources of other native species.
Invasive species are mostly spread by unintentional human activities. As aforementioned, urbanization and globalization have increased the amount of trade and transport between cities and countries. When we travel, the transportation we use or the goods we trade may carry species with them. Aquatic organisms may attach onto the bottom of the ship and get carried around; insects can get into the wood products and shipped out; ornamental plants can spread into the wild with wind blowing their seeds; and some invasive species may also be intentionally or accidentally released pets.
Impacts of Invasive Species
Impacts to the Environment
Invasive species can be either intentionally introduced or unintentionally spread outside their natural habitats. Either way, they have affected native biodiversity in nearly all types of ecosystems on earth. Given that invasive species are not originally from the ecosystem, native wildlife may have not evolved quickly enough to defend themselves against these invaders. Invasive species disrupt the original food chain of the local ecosystem. They may offer little or no food value...