These 66 Species Are Potential Biodiversity Threats to European Ecosystems

A new report published in Global Change Biology identifies 66 invasive species that could spell trouble for the European Union’s native plant and animal life.

As Stephanie Parker writes for Science News, the study, led by researchers from England’s Centre for Ecology and Hydrology (CEH), is more of a potential threat index than a current risk assessment: None of the species included on the list have been spotted in the EU—except for in captivity—but based on the team’s projections, all could arrive on the continent within the next decade, ready to wreak havoc on existing local ecosystems.

The comprehensive survey involved 43 European scientists, Megan Shersby of Discover Wildlife notes, and found researchers assessing 329 alien species through a technique known as “horizon scanning.” According to a CEH press release, this ranking method enabled the team to determine which species were “most likely to arrive, establish, spread and have an impact on biodiversity in the region” over the next 10 years.

Of the potential invaders, 66 species were deemed to pose significant threats. Eight were considered very high risk, while 40 were high risk and 18 were medium risk.

The Northern snakehead, a Chinese serpent that has devastated Japan’s native fish species, earned the unwelcome distinction of highest-risk invasive species. Rounding out the top five are the golden mussel, another native Asian species that has interfered with freshwater food webs in the United States and South America; the rusty crayfish, a native U.S. species outcompeting fellow fish in Canada; the striped eel catfish, a venomous Indian Ocean species now disrupting creatures native to the Mediterranean; and green seaweed, a so-called “ecosystem engineer” capable of altering biomes’ structure and functionality.

The final three very high-risk species are the onyx slipper snail, a critter native to California and Mexico that is now considered “highly invasive” across Asia; the black striped mussel, a Panama species that landed in the Indo-Pacific Ocean during the 1900s; and the North American fox squirrel, which competes for resources with western grey and Douglas squirrels.

As the scientists explain in the study, the highest proportion of potential invasive species originate from Asia, North America and South America. The Mediterranean, Continental, Macaronesian and Atlantic regions are predicted to be the hardest hit, while the Baltic, Black Sea and Boreal regions face the lowest threat level.

Discover Wildlife’s Shersby adds that the team’s analysis suggests terrestrial invertebrates are most likely to hitch a ride into the EU via plants, while aquatic species are expected to stowaway on ships. It’s also possible, Parker writes for Science News, that species could escape from zoos or research labs and make their way into the wild.

According to the National Wildlife Federation, invasive species include any living organisms introduced to non-native ecosystems where they can adversely affect the environment, economy or human health. Typically spread, however inadvertently, by human activity, invasive species are most harmful when they multiply rapidly, outpacing and overwhelming extant wildlife.

Examples of invasive species’ negative consequences abound: As EnvironmentalScience.org points out, 50 Canadian beavers introduced to South America’s Tierra del Fuego archipelago in 1946 have since multiplied to hundreds of thousands of gnawing creatures, decimating the region’s once plentiful forests. Returning to North America, Burmese pythons released into the Everglades by exotic pet owners have preyed on the region’s local mammal and bird populations, killing animals as varied as deer and alligators.

“Preventing the arrival of invasive alien species is the most effective way of managing invasions,” study lead author Helen Roy of CEH concludes in a statement. “Predicting which species are likely to arrive and survive in new regions involves considering many interacting ecological and socio-economic factors including climate but also patterns of trade.”

Meilan Solly | | READ MORE

Meilan Solly is Smithsonian magazine's senior associate digital editor, history.