What is an invasive species and why are they a problem?
An invasive species is a non-indigenous organism that adversely affects natural habitats and bioregions. Invasive introductions often result from careless human activity whether intentional or accidental, the results of which are likely to cause economic, environmental and/or ecological harm. While all species compete to survive, invasive species appear to have specific traits or combinations of specific traits that allow them to out-compete native species. Sometimes they simply have the ability to grow and reproduce more rapidly than native species; other times it’s more complex, involving a multiplex of traits and interactions.
Invasive species often coexist with native species for an extended time, and gradually the superior competitive ability of an invasive species becomes apparent as its population grows larger and denser and it adapts to its new location. (Note: Because the introduction of invasives is not a naturally occurring process, it does not fall under the umbrella of natural selection or survival of the fittest). With the introduction of a species into an ecosystem that can multiply and spread faster than the native species, the balance is changed and the resources that would have been used by the native species are now utilized by an invader. This impacts the ecosystem and changes its composition of organisms and their use of available resources.
Common invasive species traits include: Fast growth rates, rapid/frequent reproduction, high dispersal ability, phenotype plasticity (the ability to alter one’s growth form to suit current conditions), tolerance of a wide range of environmental conditions (generalist), and the ability to live off of a wide range of food types (generalist).
Economic costs from invasive species can occur through loss of recreational and tourism revenues. This is a particularly the case with the invasive Pterois volitans (lionfish) on Roatan where so much revenue is dependent on the tourism industry. When economic costs of invasions are calculated as production loss and management costs, they are low because they do not consider environmental damage; if monetary values were assigned to the extinction of species, loss in biodiversity, and loss of ecosystem services, costs from impacts of invasive species would drastically increase.