Alien species or invasive species? Invasive alien species? They are the same? What effects do they have on ecosystems? Surely we all know someone who has had a small turtle of those that are sold in pet stores and that, for one reason or another, has ended up in a river or lake. These actions, along with others, cause species to be redistributed across the planet, with serious consequences. At Ecologist Verde we update you on the introduction of alien species: causes and consequences. Be careful what you have at home!
The exotic species (introduced, alien or foreign) are those species that have been introduced in an area that is not within their natural range of distribution.
Its establishment is not always easy due to the characteristics of each ecosystem, which in themselves represent a set of filters that the new species must overcome in order to settle in it. They can only achieve this if they are able to reach these new areas, survive these ecosystem filters, and reproduce.
Once the filters have been passed and settled, these species may or may not cause damage to the ecosystem recently accessed, i.e. exotic species need not be a problem per se. An example of this are potatoes or corn, originating from America and which do not cause an environmental impact. In the case in which a species causes alterations in the habitat of the autochthonous species (inhabitants of that area naturally) it becomes a Invasive species.
Invasive species can be species both exotic species and indigenous species. They become invasive when the increase in their individuals produces changes in the ecosystems they access, both at the composition and structure levels and at the level of the processes that occur in it.
What happens with invasive species is that the species present prior to the invasion, not having co-evolved with these, are not capable of competing for resources, and may end up displaced or, in extreme cases, dying and becoming extinct. Therefore, these invasive species can be detrimental to the endanger biodiversity in that certain area.
It would be the result of the combination of the two previous sections. A invasive alien species It is, therefore, a species introduced artificially, accidentally or intentionally in an area that does not belong to its natural distribution and that finally overcomes the filters of the ecosystem by adapting to it and managing to invade it. Invasive alien species generally have a negative connotation since they are usually very harmful to the ecosystem, being considered one of the main causes of the loss of biodiversity worldwide.
Alien species can be introduced for a variety of reasons and ways. The rationale is trade in exotic species, but they are also among them tourism and transport such as the zebra mussel, transported on the hull of ships without being noticed.
On the other hand, they can be accidentally or intentionally introduced to be used in activities such as hunting or sport fishing (an example of an animal species used for this purpose is catfish), gardening, their use as pets, which are later they abandon and reproduce successfully (such as Argentine parrots, raccoons or Florida Galapagos tortoises), in fur, scientific reasons …
The introduction of invasive alien species (We make this distinction because, as we have said, exotic species do not have to be a problem in themselves) it causes great disorders in the biota of ecosystems, which is aggravated by other environmental problems such as deforestation, pollution of soils and aquifers or transformations in the territory. What this produces is that the imbalance that causes the mobilization of all these species in the ecosystems cannot be corrected naturally due to the speed of the process.
Not all introduced species will wreak great havoc on relationships between other species, as many will not be able to adapt to the new environment and will not survive. However, those with greater adaptability, causing even the denaturation of the ecosystem and the biodiversity loss when the death of native species fundamentals that are displaced by new arrivals. As a result, an ecosystem is obtained in which the species are not related to each other.
There is another damage more associated with the economic level. There are serious direct effects on agricultural activities and public health (for example, the Asian hornet, Vespa velutina or the tiger mosquito, Aedes albopictus). Invasions are difficult to control and eradicate, being costly and not always possible. The best solution is to identify possible invasions of these potential invasive species to prevent their growth from becoming a problem.
In Spain there are many invasive species from all kingdoms of living beings (plants, animals, protists, fungi …). All of them are listed in the “Spanish Catalog of Invasive Alien Species”, Approved by Royal Decree 630/2013.
Some examples of invasive animal species in Spain are:
On the other hand, some of the invasive plant species in Spain are as follows:
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