"We're screwed": this is how invasive species are advancing (and will continue to do so)

BarcelonaWhat species are invading and what dangers do they face? This was one of the main questions that two experts tried to answer at an event organised this Tuesday by the ARA and the Institut d'Estudis Catalans (IEC). And the answer, as always, is found in humans. Because it is theHomo sapiens who decided to build, and expand, and expand again the Suez Canal so that goods from the Indian Ocean could easily reach the Mediterranean, which caused many species from the East to also travel, by sea or stuck under ships, to the West. It has also been humans who have decided to buy, for purely aesthetic reasons, ornamental plants from other continents that have now become their own. And, once again, it is human action that has caused a climate emergency that heats the waters and disrupts ecosystems.

"We are screwed, in the natural environment we have the perfect storm," admitted Xavier Turon, biologist and member of the IEC, in a debate in which Montserrat Vilà, ecologist and member of the IEC, also participated, and which was moderated by Cristina Sáez, director of the Science supplement. At the Institut d'Estudis Catalans all the chairs were full and the debate, although many of those present were already experts in the subject, began by defining what we mean by invasive species. The starting point is that there are 1,700 exotic species in Catalonia, and 12% have invasive capacity. Vilà explained that exotic species are animals or plants that have not arrived in a region by their own means. When they begin to "cause problems", they are then considered invaders. A cypress is an introduced tree that does not cause problems. But the Pampa plumber, or the tiger mosquito, or the acacias, do, and that is why they are considered invaders.

We usually bring these species with us, and we can do so voluntarily or accidentally. For example, the species that get attached to boats arrive accidentally. But, on the other hand, it is a voluntary decision to buy a turtle from Florida. "These living beings come from ecosystems with greater diversity, with a lot of competition, and here there is a more relaxed competition," Turon explained. This is one of the triggers, in his opinion, that makes them feel comfortable and expand. For example, why are there catfish in the swamps? Vilà explained that everything comes from sport fishing, and that its fans decided to introduce these fish to catch them. They also introduced a predator into fresh water.

This is, according to experts, one of the major effects of invasive species: "Many native species change their way of life, or they die," said Turon. There is a very visual example of this with fish: if the corals or algae change, they see a distortion of where they usually lay their eggs, and they stop doing so. There are also socio-economic effects, such as species that affect agricultural or fishing areas. There are also effects on the landscape and even on public health: Vilà gave the example of the tiger mosquito.

Solutions

At this point, the main question that has hung over the debate is what can be done to deal with it. Surely, the verb "solve" is not the most appropriate to answer this question, and Turon made this clear: "When something cannot be solved, it can be mitigated," he said, and compared it to the climate emergency.

One of the keys, according to the speakers, is the "early detection" of a possible invasive species. "Either they are caught at the first moment, or everything is doomed to failure," admitted the biologist. And finding it in the first place, and especially in the sea, is not easy. For this reason, they also highlighted the key role of citizens, to warn (there are mobile applications to do so) of species that could seem new.

There are also more scientific methods, such as taking a glass of water from a lake and detecting all the DNA there. Thus, although it does not always work, new species can be found. In fact, experts have lists of possible species that could be invasive and could reach Catalonia in the coming years. Their conditions, resilience and adaptive capacity to enter a new ecosystem are being looked at. Turon has spoken of marine animals such as the puffer fish, the rabbit fish or the lion fish. The latter usually lives in colder waters, but climate change may end up making it move. It is also important, according to the participants of the event, to advance in biosecurity, and the most restrictive example is in Australia: Vilà has explained that on this island in Oceania cats cannot be removed, not even from balconies, so that they do not kill other animals in the ecosystem.