The distribution of living beings on the planet is the result of their interaction with multiple factors, such as temperature, humidity, the chemical composition of the soil, water, and air, among many other factors, known as abiotic factors.
In parallel with this interaction, living beings also interact with each other, establishing a vast set of biotic relationships which, under normal conditions, allow for the control of the species present and ensure the balance of the ecosystems to which they belong.
The species that, as a result of this slow and complex evolutionary process, have settled in the various environments, have become an integral part of them, ensuring the dynamic balance of the ecosystems in question, and are referred to as indigenous, native or autochthonous species, in a clear reference to their original habitat, to which they are adapted, and the rest of the ecosystem is adapted.
It is possible – as a result of natural or intentional processes – for some species to be introduced into environments to which they are foreign, thus being called alien or exotic species. Many of these species adapt and survive in their new environments, being able to interact with native species in a non-aggressive way and thus begin a long period of adaptation to the ecosystem in question.
On the other hand, the introduction of exotic species can develop into a more aggressive process which, once installed, and in the absence of predators or other control agents, begin a process of rapid reproduction and dispersal, with the implicit loss of balance in the ecosystems in question and immediate repercussions in terms of the loss of autochthonous biological diversity. Because of their invasive nature, these species are known as Invasive Alien Species (IAS).
How IAS proliferate
IAS can reach new environments as a result of natural processes or as a result of human action. Natural events such as hurricanes or torrential downpours can transport seeds or fruit over great distances. Human action ends up being the main force for importing living beings from other continents, whether on purpose or accidentally, as in the case of bivalves being transported in ship hulls or insects in freight containers, among many other possibilities.
Currently, all these factors are greatly aggravated as a result of Climate Change, which introduces new environmental variables, favouring the conditions in which IAS can settle, disperse and occupy habitats, while native species tend to reduce their populations and, ultimately, may become extinct. Cumulatively, the current process of globalisation, promoting the rapid movement of people and goods around the planet, is also proving to be an ally of IAS, favouring the dispersal of these beings on a planetary scale in very short periods of time.
Globally, there are around 3,500 well-established IAS, and their geographical spread has been increasing at a worrying rate, with an estimated 200 new invasive species per year, with more or less significant impacts in various areas (Roy et al., 2023). In Europe, it has been possible to identify 14 main types of impacts of IAS, which can be grouped into 4 levels, namely biological diversity, ecosystem services, human health, and economic activities (EEA, 2012).
Impact of IAS dispersion
Impacts on biological diversity contribute to the imbalance of populations of native species and their habitats, particularly through direct action on biotic relationships (competition, predation, among others), the introduction and transmission of diseases and hybridisation of native species. These impacts are particularly significant and visible when they occur in macroscopic beings, but their action is also felt in the microscopic world, altering the functioning of ecosystems. An example of this type of imbalance can be easily seen by simply looking at the riparian galleries, whose occupation by reeds (Arundo donax) implies the loss of native plant and animal diversity.
The impacts on ecosystem services are numerous and can be illustrated by the changes made to the quality of water bodies by the presence of aquatic invasive species such as azolla (Azolla filiculoides) or water hyacinth (Eichhornia crassipes), which can contribute to their eutrophication.
The impacts of IAS on human health can be manifold, and those associated with allergies and skin diseases are commonly mentioned. Some IAS can be vectors of disease, as is the case, for example, with the Asian tiger mosquito (Aedes albopictus), which has already been identified in Europe and is a vector for transmitting Zika, chikungunya and dengue.
The impact of IAS on economic and social activities is felt in many areas, such as fisheries, agriculture, and food production. In this case, an easily identifiable example is the impact of the Asian hornet (Vespa velutina) on the pollination process and the extinction of native bees.
Possible solutions
Given the seriousness of the impacts of the occurrence of IAS, solutions must be sought to detect, control and eradicate them, which are always complex and particularly costly processes, as evidenced by the investments of around 12 billion euros in Europe in 2008 (Kettunen &all, 2009) and 80 billion euros annually in the United States.
Early detection and rapid eradication are a strong contribution to the fight against IAS, without prejudice, of course, to community awareness campaigns about this serious environmental problem.
- References:
EEA (2012). The impacts of invasive alien species in Europe. Disponível AQUI.
- Roy, H. E., Pauchard, A., Stoett, P., & Renard Truong, T. (2023). IPBES Invasive Alien Species Assessment: Factsheet 1 – Invasive alien species: data on trends and impacts. Zenodo. https://doi.org/10.5281/zenodo.10057014
Kettunen, M., Genovesi, P., Gollasch, S., Pagad, S., Starfinger, U., ten Brink, P. and Shine, C. (2009). Technical support to EU strategy on invasive species (IAS) — Assessment of the impacts of IAS in Europe and the EU, Final report for the European Commission, Institute for European Environmental Policy (IEEP), Bruxelas, Bélgica
- Life Invasaqua (s/d). Life Invasaqua. Disponível AQUI.
Roy, H. E., Pauchard, A., Stoett, P., & Renard Truong, T. (2023). IPBES Invasive Alien Species Assessment: Factsheet 1 – Invasive alien species: data on trends and impacts. Zenodo. https://doi.org/10.5281/zenodo.10057014
- Toland, J (Editor) (2014). Life and Invasive Alien Species. Publications Office of the European Union, Luxemburgo
União Europeia (2009). Natureza e biodiversidade – Espécies Alóctones Invasivas. Disponível AQUI.
