natural reserve
High costs: Invasive species are a massive problem
An Asian hornet (Vespa velutina nigrithorax). photo
© Axel Heimken/dpa
The Japanese beetle that eats away fields, the Pacific oyster that changes the currents in the Wadden Sea, and a new fungus that kills salamanders: invasive species cause huge damage.
They displace native animals and Plants, destroy entire ecosystems and cause hundreds of billions of euros in damage every year: According to an international report, so-called invasive species are a problem that has so far been massively underestimated.
Species that have been introduced or intentionally settled are considered to be one of the main reasons for the global decline in species. And as more and more people travel and ever larger flows of goods are exchanged, the problem is likely to increase in the future.
The report was published by the Bonn-based World Biodiversity Council (IPBES). 86 experts from 49 countries worked on it for four years.
“It is the first report that treats the problem so globally and comprehensively,” said Sven Bacher, professor of ecology and evolution at the Swiss University of Freiburg, the German Press Agency. “Now we finally have a database that we can use to show the magnitude of this phenomenon.”
About 3500 invasive species – and a high number of unreported cases
According to conservative estimates, a total of 37,000 alien species have now been transported from their natural range to other regions by human activity. About 3500 of these species cause damage – they are the invasive species. The annual economic cost was $423 billion in 2019, according to the report.
For Germany, the Federal Agency for Nature Conservation (BfN) lists 900 non-native species, of which around 90 are invasive. “These numbers are very conservative,” says IPBES expert Hanno Seebens. “According to our databases, we have at least 2,600 established alien species in Germany, some of which are invasive.” All these numbers only refer to documented species – there is certainly a high number of unreported cases.
An invasive species can transform entire ecosystems
For example, one invasive species is a fungus called salamander plague, which is deadly to fire salamander populations. It spread from the Netherlands to Germany. “In recent years we have also found it in Bavaria, and now we are very afraid that it will spread further,” explains Bacher.
But there are also invasive species that change entire ecosystems. “One could cite the Pacific oyster, which forms large oyster beds in the North Sea and thereby even changes the flow conditions in the Wadden Sea. The habitat as a whole is thus strongly influenced by a single invasive species.”
In addition to this natural damage, there is also severe economic damage. Muskrats – originally introduced for their fur – often destroy bank reinforcements. The Japanese beetle, on the other hand, descends on fields like a biblical plague and eats everything bare. In Switzerland, on the other hand, pesticides are also used in private gardens.
transplanted from humans
Seebens, it is important to emphasize that it is not the invasive species themselves that trigger this development, but the people who transplant them from one continent to another. Since the 1950s, the distribution of alien species has been increasing worldwide – and at an ever faster rate. “We are currently reaching a dimension of around 200 new species worldwide every year,” says Seebens. The driving forces behind this, such as international trade, but also the destruction of habitats are increasing. “There are no signs that this trend will weaken in any way – on the contrary.”
The positive news is that, according to the unanimous opinion of the scientists, there are tried and tested, efficient countermeasures. “The best thing, of course, is to prevent the spread of such species from the outset – through prevention,” emphasizes Bacher. “There are already international agreements, for example for shipping, for ballast water, but the problem is that they are not properly complied with.” The scientists are therefore calling for stricter controls. A more coordinated approach is also important. It makes little sense to fight the problem only at the local level, because invasive species naturally do not respect administrative and national borders.
The individual is also asked. “For example, many of us have non-native, maybe even invasive, exotic plants in our garden,” says Bacher. “Or another example: We travel to more and more remote areas, then fly back and use the hiking boots here, which still have dirt on them from the other side of the world. In this way, we may even contribute to the colonization of completely alien species here. “