An invasive species is a type of animal, plant, fungus or any living being that reaches a new habitat (usually due to the hand of man) and that can damage the native species of the place. Thus, as Katharine Suding, an ecologist at the University of Colorado, argues, an invasive species is almost always from elsewhere, and there is concern that it could damage the ecosystem.
There are more and more invasive species. Of all the invasive species discovered during the last 200 years, about 40% were discovered after 1970. This is what a study published in the journal Nature Communications maintains.
How do invasive species arrive?
Typically, invasive species come to the new environment as people’s pets. It is also common for them to appear on boats and manage to reach another area.
Global trade regularly brings species to new parts of the world, either inadvertently or deliberately. In fact, research published in the Journal of Applied Ecology suggests that the increase in invasive species is due to globalization, economic growth, and international transportation.
Some of the countries with the most invasive species are the United States, France, Australia and China, according to a study published in the journal Global Ecology and Biogeography
Why are they a problem?
Invasive species harm native species, either directly or indirectly. For example, in 2010 scientists discovered a South American fungus (Austropuccinia psidii) in Australia.
When this fungus spreads through the eucalyptus trees of Australia, it takes hold of them, removing the leaves from the branches and stunting their growth. This fungus is a perfect example of how invasive species act in ecosystems.
Similarly, a fish called bighead carp ( Hypophthalmichthys nobilis ) was transported from China to the United States in 1973 and now swims around the Mississippi River basin, gorging on plankton.
Plankton forms the basis of the watershed’s food web, so when plankton are eaten by carp, there is a food shortage for native filter-feeding fish.
And, when these small fish starve and subsequently disappear, so do the larger fish that eat them.
