Spain carries "protecting" to the Italian crayfish since Philip II. The problem is that it is an exotic species

We often hear about the many invasive alien species of animals and plants (including fungi) that threaten our ecosystems. From the gray hair We see catfish on the river banks, the list also includes crustaceans and even mammals.

We rarely talk about other species introduced by humans into our ecosystems that They are not considered invasive.. Some are even welcomed by the authorities in charge of protecting these ecosystems.

Probably the best example we have on hand is the Italian crayfish (Austropotamobius fulcisianus).

Miguel Clavero Pineda is an expert at the Doñana Scientific Station and has thoroughly studied this species introduced to the Peninsula in the 16th century by none other than the ruling monarch: Philip II.

In an article recent for The Conversation, Clavero Pineda reviews the history of this species in Spain, from its introduction to the 20th century. A history in which the Italian crab has been far from being considered a threat to our ecosystems. Quite the opposite: the Italian crab has enjoyed the approval and protection of the authorities for many years.

It was in the 20th century when river fishing became an economic activity promoted by the State. Within this framework, various releases of this and other river species were carried out.

Curiously, explains Clavero Pineda, this type of action would be what put a stop to the expansion of this species throughout the Peninsula. The reason: the arrival in the mid-1970s of the American red crab (Procambarus clarkii).

But Clavero Pineda’s article is more than a mere review of the history of this crustacean: in it he also talks about the implications of the protection that the species has received. The expert points out that protecting an introduced species represents a significant opportunity cost: Spending our efforts on its conservation means having fewer resources for native species that also require this coverage.

The difficult coexistence between this species and the red crab is another problem for the expert. The releases of this crab are usually carried out taking advantage of stretches that the red crab has not yet occupied. As explains Clavero Pinedathe conservation of species such as the Iberian desman or some leeches may be threatened by these releases.

Invasive or not

The history of the Italian crab has some parallels with that of other introduced species but not considered a threat by the authorities: the eucalyptus. Native to Oceania, trees of the genus Eucalyptus They were introduced into Spain in the mid-19th century and have become one of the most controversial plants in the entire peninsula.

The movement to include eucalyptus trees in the Spanish Catalog of Invasive Exotic Species It has been gaining traction in recent years but the answer today is a resounding “no”. The reason given in 2018 was that this was a controlled species adapted to its environment. In addition to being a source of income for those who grow it.

This does not mean that all introduced species are harmful. There are cases of greater consensus in which these species generate a positive net contribution to their new environment. In another article for The ConversationHeather Kharouba and Stephanie A. Rivest, from the University of Ottawa, compiled a compilation of cases of introductions of species whose introduction had resulted in benefits to the ecosystem.

The authors cite, for example, the case of the observed relationship on Vancouver Island between native butterflies and some introduced flowers. Faced with food shortages in summer, when native flowers are scarce, the butterflies resorted to nectar from introduced flowers.

Kharouba and Rivest also put the example Ridgway’s Rail (Rallus obsoletus), a species native to the west coast of North America. The introduction of a foreign plant, Sporobolus alterniflorushas also helped the survival of this bird, in this case not by serving as food but as shelter: these birds use these herbs to build nests and protect themselves from predators.

There are more examples. In another article, this in Scientific AmericanSamuel B. Case of the University of Wyoming pointed out another relationship between birds and plants, this one in Hawaii. In this case, the disappearance of native birds had left a void in the ecosystem because native plants needed these animals to distribute their seeds. The introduction of exotic birds sealed that void, helping the native plants to reproduce for generations to come.

The appropriateness or inappropriateness of the introduction of an external species into an ecosystem is something that can only be studied case by case and, what is perhaps even worse, its full implications can only be known a posteriori. That is why the precautionary principle is the logical path in these cases. Even more so in contexts where there are species or entire ecosystems in vulnerable situations.

In Xataka | We have been reintroducing the European bison to the Iberian Peninsula for years. The problem: maybe he never lived there

Image | Stilleven met visby Clara Peeters. Table showing some of the species introduced by Philip II.