Invasive but threatened


Friday, 25 May 2018

Invasive alien species (IAS) are considered one of the main causes of biodiversity loss globally, costing billions of euros to the global economies. International conventions, national legislations, and projects aim to tackle the introduction, the spread and the adverse effects of IAS on biodiversity.

But there are also cases where IAS are listed as threatened facing extinction in their native home range: for example the Eurasian Beaver (Castor fiber), the Monterrey Cypress (Cupressus macrocarpa) and the antilopes. Such species were intentionally introduced by humans for commercial purposes or as ornamental animals and soon escaped or were released. This is also the case of the Wattle-necked Soft-shelled Turtle (Palea steindachneri) in Hawaii. The species originates from China, where it is considered valuable as a food source. For this reason Chinese immigrants brought individuals when migrating to Hawaii back in 1850s. Currently the species has established an invasive population in some of the islands, threatening the local biodiversity. Interesting is the case of the African Sacred Ibis (Threskiornis aethiopicus). The species is associated with Thoth, an ancient Egyptian god, and is appreciated by the local communities. However, the African Sacred Ibis is extinct from Egypt, while currently is invading Europe, creating many problems to its biodiversity (spreading diseases, competing for nests, feeding with threatened species of insects etc.) and is listed as IAS of Union concern, under EU Regulation 1143/2014 (link) .

Such paradoxes puzzle scientists, conservationists and policy makers. Sometimes the decision to eradicate an IAS species that is threatened by extinction within its home range, can be replaced by reintroduction projects. In native areas. Similar situations are expected to increasingly challenge decision makers in the future due to the anthropogenic impact on biodiversity.

Photo credit: @Mathieu Breitenstein

Useful links

The conservation paradox of endangered and invasive species

Approved — Three amigos exempted from endangered species list

Threat or threatened species? A paradox in conservation biology