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Kiel (dpa) - Animals and plants introduced from other regions of the world can cause damage running into billions.
This is especially true when they displace commercially used species or cause diseases in humans, reports an international research team headed by the Geomar Helmholtz Center in Kiel.
Accordingly, the economic damage caused by invasive aquatic species totaled more than 20 billion US dollars (almost 17 billion euros) worldwide in the past year alone.
So far, scientists have primarily examined the ecological consequences of invasive animals and plants, the researchers write in the journal “Science of the Total Environment”. In what they claim to be the first global data analysis, the 20 scientists from 13 countries compiled the economic costs that are specifically caused by aquatic invaders - i.e. by water dwellers.
"We come to the conclusion that invasive aquatic species that have established themselves in their new habitats have cost at least 345 billion US dollars since the 1970s," says first author Ross Cuthbert from Kiel.
Invasive mussels, for example, can clog the intake pipes of factories, power plants or water treatment plants.
Or alien parasites could "cause catastrophic incursions into commercial fisheries."
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Ultimately, the researchers suspect that the global costs of introduced species are much higher.
Ecologist Cuthbert emphasizes that the real costs are greatly underestimated due to gaps in knowledge.
“For many countries and known harmful invasive species, especially in Africa and Asia, costs have never been reported.
So we can assume that the damage is actually much higher. "
A comparison with the costs caused by invasive species on land confirms this, the team emphasizes.
While aquatic species made up a quarter of the documented invasive species, the economic cost they caused was only a twentieth of what is known of terrestrial species, it is said.
For the study, the team used cases that were documented in the literature and created a database from them.
In water bodies, invertebrates caused the largest proportion of the costs determined, at 62 percent.
Vertebrates were responsible for 28 percent, plants for six percent.
The largest costs were reported in North America (48 percent) and Asia (13 percent).
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It is worrying that less than a tenth of the amounts invested to repair damage would be spent on management measures such as preventing future invasions, the scientists write.
They call for more resources to be invested in the management and prevention of invasions.
"That would be money well spent to prevent and limit current and future damage," says Cuthbert.
According to the Federal Agency for Nature Conservation, around 900 alien animal and plant species have permanently established and spread in nature in Germany over the past 500 years.
In addition, there are around 1640 alien plant, 38 mushroom and 460 animal species that have so far only been detected sporadically.
© dpa-infocom, dpa: 210420-99-272520 / 2
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Global economic costs of aquatic invasive alien species
Federal Agency for Nature Conservation