The introduction of species into ecosystems where they are not found naturally can have very serious consequences for biodiversity. These species can establish themselves, reproduce and colonize new places, replacing the native flora or fauna and altering the functioning of the ecosystem.
Currently, invasive species are the second leading cause of biodiversity loss in the world, preceded only by habitat loss. Although introductions have occurred since the first human migrations, they have multiplied in recent decades due to global trade. If you want to know more, don't miss this article on our site about invasive species: definition, examples and consequences
Invasive Species Definition
According to the International Union for Conservation of Nature (IUCN), an “invasive alien species” is an alien species that establishes itself in an ecosystem or natural or semi-natural habitat, becoming aagent of change and a threat to native biological diversity.
Therefore, invasive species are those capable of reproducing successfully and forming self-sufficient populations in an ecosystem that is not their own. When this happens, we say they have “naturalized”, which can have unfortunate consequences for native species.
Some introduced exotic species are not capable of surviving and reproducing on their own, so they end up disappearing from the ecosystem and do not endanger native biodiversity. In this case, they are not considered invasive species, but only introduced
Origin of invasive species
Since the existence of human beings, they have made great migrations and have taken with them species that have helped them survive. Transoceanic shipping and exploration greatly increased the number of invasive species. However, the globalization of trade that has taken place over the last century has exponentially increased the introduction of species. Currently, the introduction of invasive species has various origins:
- Accidental: Animals “hidden” in boats, ballast water or cars.
- Pets: It is very common for people who buy pets to get tired of them or cannot take care of them, so they decide to release them. Sometimes they do it thinking that they are doing a good deed, but they do not take into account that they endanger the lives of many other animals.
- Aquariums: the discharge of water from aquariums in which there are exotic plants or small animal larvae has led to the invasion of rivers and seas by many species.
- Hunting and fishing: Both the rivers and the mountains are full of invasive animals released by hunters, fishermen and sometimes the administration itself. The goal is to capture colorful animals as a trophy or food resource.
- Gardens: Both public and private gardens grow ornamental plants that are highly dangerous invasive species. Some of these species have come to displace native forests.
- Agriculture: Plants grown for food, with few exceptions, are not usually invasive plants. However, seeds and arthropods that have colonized the world, such as many adventitious grasses (“weeds”), slip through during transport.
If you want to know more about the consequences of using exotic species as pets, we recommend this other article on Animals that should not be pets.
Consequences of the introduction of invasive species
The consequences of the introduction of invasive species are not immediate, but are observed long time has passed since their introduction. Some of these consequences are:
- Extinction of species: Invasive species can wipe out the animals or plants they consume, as they are not adapted to predation or to the voracity of the new consumer. In addition, they compete for resources (food, space) with native species, displacing them and causing their disappearance.
- Alteration of the ecosystem: as a consequence of their activity, they can alter the food chain, natural processes and the functioning of habitats and ecosystems.
- Disease transmission: Alien species carry pathogens and parasites from their places of origin. Native species have never lived with these diseases, so they often suffer a high mortality rate.
- Hybridization: Some introduced species may breed with other native varieties or breeds. As a consequence, the native variety may disappear, reducing biodiversity.
- Economic Consequences: Many invasive species become crop pests, decimating harvests. Others adapt to living in human infrastructures, such as pipes, causing great economic losses.
To prevent the extinction of native species, we advise you to read this other article on our site on How to protect animals in danger of extinction?
Examples of invasive species
There are already thousands of invasive species around the world. In this article on our site, we leave you some examples of the most harmful invasive species.
Nile Perch (Lates niloticus)
These huge river fish were introduced into Lake Victoria (Africa). In a short time, caused the extinction of more than 200 species of endemic fish due to their predation and competition. It is also believed that the activities derived from its fishing and consumption are related to the eutrophication of the lake and the invasion of the water hyacinth (Eichhornia crassipes).
Wolf snail (Euglandina rosea)
It was introduced to some Pacific and Indian islands as a predator of another invasive species: the snail African giant (Achatina fulica). This had been introduced as a food resource and pet in many countries, until it became an agricultural pest. As expected, the wolf snail not only consumed the giant snail, but also wiped out many indigenous species of gastropods.
Caulerpa (Caulerpa taxifolia)
Caulerpa is probably the most harmful invasive plant in the world It is a tropical algae that was introduced into the Mediterranean in the years 80, probably as a result of the discharge of water from an aquarium. Today, it is already found throughout the western Mediterranean, where it is a threat to native grasslands, where numerous animals breed.
