Frequently Asked Questions
about alien species
What is an alien species?
According to the EU regulation 1143/2014, an alien species (AS) is any live specimen of a species, subspecies or lower taxon of animals, plants, fungi or micro-organisms introduced outside its natural range; it includes any part, gametes, seeds, eggs or propagules of such species, as well as any hybrids, varieties or breeds that might survive and subsequently reproduce
What are invasive alien species?
Invasive alien species (IAS) are AS whose introduction or spread has been found to threaten or adversely impact upon biodiversity and related ecosystem services.
How do marine invasive species invade new environments?
According to the Convention of Biological Diversity (CBD), there are several different pathways that alien species are being introduced in new environments. With respect to the marine AS, they are being introduced through various means, such as corridors(connected waterways, such as the Suez Canal), ballast water of ships, attached to ship-hulls and other water submerged parts (e.g. anchors), aquaculture activities, marine debris, or intentional introductions (e.g. aquarium releases). Some species, once migrating into a new environment, can also spread naturally, expanding their distribution.
What are some examples of marine invasive alien species in the Mediterranean?
Some notable examples of marine invasive alien species in the Mediterranean Sea include:
Devil firefish or Lionfish (Pterois miles), Silver-cheeked toadfish (Lagocephalus sceleratus), Bluespotted cornetfish (Fistularia commersonii), Porcupine sea urchin (Diadema setosum), Marbled and Dusky spinefoot (Siganus rivulatus and Siganus luridus), Atlantic Blue Crab (Callinectes sapidus), Red sea plum (Asparagopsis taxiformis).
What impact do alien species have?
AS can negatively impact biodiversity, ecosystem services (such as fisheries, tourism) and human health.
What impacts do invasive alien species have on local ecosystems?
These species can severely impact biodiversity, outcompete native organisms for resources, alter food webs, change the structure of marine habitats. They may also introduce new diseases, which can harm native species. Moreover, invasive alien species often lack natural predators in their new environments, allowing them to thrive unchecked. All the above can make ecosystems less resilient to other pressures, like pollution and further facilitate the arrival and establishment of more alien species. The latter is also induced by climate change and increasing water temperature.
How do invasive alien species affect ecosystem services and the economy, especially fishing and tourism?
They can indeed affect commercial fisheries, as they damage the fishing gears, either by destroying nets and longlines, or by clogging the nets, the damage catches as they prey on commercial species that are being caught, or by competing with or preying on native fish stocks, leading to economic losses. They can also degrade habitats important for tourism, such as coral reefs and increase the costs of managing and removing them. There are species that have painful stings, such as the Nomadic jelly fish (Rhopilema nomadica), that if a person is allergic this might lead to hospitalization.
What role do humans play in the introduction of marine invasive species?
By definition, humans are responsible for allowing species to move outside their natural distribution. In modern years, human activities like global shipping (through ballast water), aquaculture and the pet trade further enhance the phenomenon, and are considered as major pathways for the introduction of alien species. Even recreational boating and water sports can unintentionally spread them.
Is there anything that we can do to prevent the arrival, establishment and spread of alien species?
YES! With respect to arrival, people could help by not releasing aquarium/terrarium pets into the wild. Recreational fishers should clean very well their fishing gear and equipment, and not release live bait into the environment. We should not move wildlife from one place to another (e.g. tropical flowers and fishes look nice in their native environment and aquaria, but they can create huge issues in invaded areas). Finally, we could find mitigation measures, such as exploiting alien species.
How can alien species be exploited for beneficial purposes?
Invasive alien species can be exploited in many ways, such as being used in commercial products or as food sources. For example, mullets, cornetfishes and blue crabs, as well as other edible alien species, are often targeted for culinary use. Tetrodotoxin, which makes L. sceleratus unexploitable and inedible, is a compound with high bioactivity and several potential applications in medicine and pharmacy. In addition, some invasive algae are harvested for use in cosmetics, medicines or as fertilizers. However, these approaches must be handled carefully to avoid further ecological disturbances.