Alien species will increase by the thousands over the next three decades

Within the next three decades, alien species will increase by more than 35 percent compared to 2005, according to a new study from University College London. The international team of researchers reports that potentially invasive plants, arthropods, and birds are being introduced to new environments at the fastest overall rate. 

“Increases are expected to be particularly large for insects and other arthropods, such as arachnids and crustaceans. We predict the number of aliens from these groups to increase in every region of the world by the middle of the century – by almost 120% in the temperate latitudes of Asia,” said study co-author Dr. Franz Essl of the University of Vienna. 

Alien species are plants and animals that humans have moved to regions of the world where they do not occur naturally. When non-native species become invasive, they are capable of altering habitats, disrupting the balance and function of ecosystems, and wiping out native species by competing for limited resources.

The experts predict that around 2,500 new alien species will arrive by mid-century in Europe alone. This means that non-native plants and animals will increase by 64 percent across the continent in a 45-year period. The researchers hope it is possible to reduce the number of alien species with stricter biosecurity regulations.

“Our study predicts that alien species will continue to be added to ecosystems at high rates through the next few decades, which is concerning as this could contribute to harmful biodiversity change and extinction,” said study co-author Professor Tim Blackburn. “But we are not helpless bystanders: with a concerted global effort to combat this, it should be possible to slow down or reverse this trend.”

The most recent global assessment, which was conducted in 2005, documented 35,000 alien species. For the current study, the research team developed a mathematical model to estimate how many more aliens can be expected by 2050 based on the current rate. 

The model revealed that there will be a 36-percent increase in non-native species by 2050 compared to the numbers recorded in 2005. While Europe will see the biggest influx of non-native plants and animals, Australia is expected to see the least.

“These will primarily include rather inconspicuous new arrivals such as insects, molluscs, and crustaceans. In contrast, there will be very few new alien mammal species such as the well-known raccoon,” said study lead author Dr. Hanno Seebens of the Senckenberg Biodiversity and Climate Research Centre. 

“We will not be able to entirely prevent the introduction of alien species, as this would mean severe restrictions in international trade. However, stricter regulations and their rigorous enforcement could greatly slow the flow of new species.”

“The benefits of such measures have been shown in some parts of the world. Regulations are still comparatively lax in Europe, and so there is great potential here for new measures to curtail the arrival of new aliens.”

The study is published in the journal Global Change Biology.

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By Chrissy Sexton, Earth.com Staff Writer