18.01.2019 change 18.01.2019
Anna Ślązak
Anna Ślązak

Scientists identified new invasive species threatening the EU environment

Photo: Fotolia Photo: Fotolia

Species previously not found in Europe, including fish, crayfish or squirrel, are among the most dangerous invasive alien species that can threaten the nature in Europe. Most of them come from the tropical zone, they would have little chance of survival in Poland, according to a biologist from the Institute of Nature Conservation of the Polish Academy of Sciences in Kraków.

More than 40 scientists from across Europe participated in the study led by Prof. Helen Roy from the UK Centre for Ecology & Hydrology. They evaluated the risk posed by various animals and plants in all environments. They estimated the probability with which these alien species could get into Europe, settle and spread, as well as their negative impact on native species. The impact of these species on biodiversity in the European Union can be felt already in the next decade.

The most species potentially dangerous for the EU`s natural environment come from Asia, North and South America. Aquatic species can be accidentally brought to Europe mainly via long-distance shipping, and terrestrial invertebrates can invade, for example, with imported plants. The biogeographic regions most threatened by potential invasions of new alien species on our continent are: the Mediterranean and continental regions, and the region of volcanic islands in the Atlantic, off the coast of Europe and Africa.

A much lower risk applies to areas near the Baltic Sea, the Black Sea and the polar regions. It also appears that no new alien species threaten the high-mountain nature, experts assess.

The highest risk category was assigned to seven species of animals and one plant.

One of these species is the predatory perciform fish Channa argus, which comes from the southern and eastern parts of China. Currently, it can also be found in shallow, marshy ponds and wetlands in Japan and Florida. The next species is the striped eel catfish (Plotosus lineatus) that occurs in the Indian Ocean. It was noticed in the Mediterranean in 2002. It conquered the coast of Israel, especially shallow waters with sandy or muddy bottoms. This fish produces a toxin that is potentially dangerous for humans. From the environmental point of view, its presence means competition for native species of fish, and in the long run also the risk of their extinction.

Scientists also warn against two species of molluscs. One of them, Limnoperna fortunei, represents the Mytilids family. It comes from China and Southeast Asia; in 1965 it appeared in the waters of Hong Kong, and in the 1990s also in Japan and Taiwan. With time, it spread to the waters of the USA and South America. It affects the local fauna and food networks in fresh water. Another mussel - Mytilopsis sallei comes from the coast of Panama, but has spread in the waters of the Indian Ocean and the Pacific, reaching Fiji, India, Malaysia, Taiwan, Japan and Australia.

Another top threat is the snail Crepidula onyx, originating from the waters of California and Mexico. Today it is widespread and considered a very invasive species in Asia. Its presence has been recorded in Korea, Japan and Hong Kong.

Another animal that made the list of potentially dangerous invasive species in the EU is Orconectes rusticus, a freshwater crayfish native to the United States, found also in the waters of Canada. It is large and aggressive; it threatens native species of crayfish.

Terrestrial vertebrates are represented by the fox squirrel (Sciurus niger), native to North America, which competes for resources with other species of squirrels. It is also potentially dangerous for our red squirrel (S. vulgaris).

Among the plants, the authors of the report mention the Codium parvulum algae from the Indian Ocean and the Pacific Ocean. It is already present in the Red Sea and the Mediterranean. Scientists believe that the presence of this species affects the structure and functioning of ecosystems.

"Most of these species come from the tropical zone, and even if they reach Poland, they have little chance of surviving" - says Wojciech Solarz from the Institute of Nature Conservation PAS in Kraków, who took part in the work of the team that prepared the list of invasive threats.

But he points out that an alien species can be dangerous to nature even if it does not settle in a new place. Even then, there is a risk of transmitting diseases or parasites.

"The crayfish Orconetctes rusticus and the fox squirrel that come from North America, from climatic zones similar to ours, would have the best chance for settling in Poland. In the long run their presence could mean competition for native species, they could transfer parasites or diseases, even cause economic losses" - says Dr. Solarz.

He notes that so far none of these species has been found in nature in Poland and there aren't any reports of farming them in our country.

The eight species listed above are the top of the list of 329 alien species that are potential threats to the EU`s ecosystems. The complete list has been published in the journal "Global Change Biology". The study was financed by the European Commission.

It is estimated that there are already over 14 thousand alien species in Europe, of which more than half come from areas outside the European Union (the others are typical only for specific areas within the EU, but have spread and taken over new areas in Europe).

A large part of alien species are spreading as "stowaways", for example on sea or land transport. Others are imported intentionally for breeding, either for consumption purposes or as pets, Dr. Solarz notes. This was the case, for example, for North American crayfish that were brought to Europe for breeding and then released (or escaped themselves). Both North American species are carriers of a water mould that causes plague and is lethal to European crayfish.

Although it is impossible to completely eliminate the introduction of alien species, it is worth trying, because they often pose a threat, says the scientist from the Institute of Nature Conservation PAS. "According to the Red List of Threatened Species, in the world there are over 200 species that have gone extinct as a result of the introduction of invasive alien species. In Poland, American mink, raccoon and raccoon dog are also a problem, as they can threaten bird broods... Recently, in Nysa, there was the first case of breeding of rose-ringed parakeet in Central Europe. Its possible spread may threaten native species of birds, for example because of the competition for nesting hollows" - he explains.

Dr Solarz notes that only two of the top alien species threatening the EU are potentially dangerous from the perspective of Poland. But the American bison (Bison bison) is also considered a big threat. From the perspective of the whole of Europe it is not very important, in some Western European countries it is even kept on half-open farms. "The situation in Poland is different because of our European bison, which is still an endangered species due to its small population. There are less European bison than white rhinoceroses in the world! The presence of American bison, even on farms located, for example, close to free-living European bison herds, would be very large a threat due to the potential transmission of diseases and the risk of interbreeding" - explains Dr. Solarz.

Invasions of alien species are the second greatest threat - after direct destruction of habitats - to global biodiversity. In addition, they generate very high economic losses, which in Europe alone reach at least EUR 12 billion a year. According to Dr. Solarz, creating a list of alien species potentially dangerous for EU ecosystems is a preventive measure.

Such a list can be helpful when expanding the list of invasive alien species and invasive species subject to special regulations in the EU. Currently, there are 49 species that may not be imported, kept, bred or sold in Europe. If they are found in any country in Europe, that country has an obligation to take actions that will eliminate the species or prevent its expansion - explains the scientist.

PAP - Science in Poland, Anna Ślązak

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