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Economic time bomb: Costs of invasive species are greatly underestimated

Biological invasions, a prominent threat to natural ecosystems, biodiversity, and human health, are known for wreaking havoc on the environment. Invasive species lead to ecosystem degradation and incur substantial economic costs, often measured in multi-trillions of euros globally. 

Now, a study led by McGill University is highlighting the severe economic burden these biological invasions are likely to place on the European Union (EU) if left unchecked.

Thousands of invasive species

The EU is at an increased risk of invasions by alien species – harmful species that are introduced by humans from outside their natural habitats. Thousands of such invasive alien species pose a constant threat to the EU. 

The risk is further amplified due to the region’s high volume of economic activities such as trade and transportation of goods, which inadvertently increase the opportunities for biological invasions. This pivotal finding comes from the study, which was recently published in the journal Environmental Sciences Europe.

Costs are underestimated 

A key issue identified by the researchers is that most of these invasive alien species are not sufficiently evaluated for their actual and potential economic impacts. Consequently, the resulting cost estimates are often substantially underestimated. 

To investigate, the researchers set out to quantify the economic fallout of biological invasions in the European Union. Utilizing predictive models, they estimated the future costs of these invasions.

Alarming results

The experts found that out of approximately 13,000 invasive alien species known to have established populations in the EU, reported costs exist for a mere 259 species, a small fraction constituting around one percent. This highlights the substantial knowledge gap in regional cost assessments. 

The researchers’ predictive models projected unreported costs to be potentially 501 percent higher than the currently recorded costs, amounting to a staggering €26.64 billion (US$28.0 billion). The burden of these costs appears to be heaviest on countries such as Lithuania, Malta, and the Czech Republic.

Even more concerning are the study’s future cost projections. The research predicts a significant surge in costs, with estimates potentially soaring to more than €142.73 billion (US$150 billion) by 2040 in the absence of effective management measures.

“Our study reveals a shocking underestimation of the economic costs of biological invasions in the European Union. These costs are not only a huge burden for the European Union’s economy but also jeopardize the ecological balance and well-being of societies,” said study lead author Morgane Henry, a PhD student under the guidance of Professor Brian Leung at McGill University.

Action is urgently needed

Henry further emphasizes the urgent need for action: “It is imperative that we take immediate action to enhance cost reporting, identify the most concerning economic impacts, and work together on a global scale to address the threat posed by invasive alien species.”

The research sounds a strong warning to policymakers, scientists, and stakeholders alike, urging them to recognize the implications of their findings. The experts stress that without collaborative efforts to protect ecosystems, preserve biodiversity, and secure the well-being of communities, biological invasions could potentially create an overwhelming financial burden. To prevent the devastating ecological impacts, the EU and its governments must take swift action.

“The costs are potentially huge, but in most cases we just don’t know. Notably, our fivefold increase in cost estimates included only 1% of species with existing data, by extrapolating to other countries where they are known to have invaded, but where costs have not been estimated yet. We don’t know about the other 99% of the species,” said Professor Leung, emphasizing the vast unknown associated with these invasive species.

Invasive species in the EU

The European Union (EU) has had its share of invasive species, which have established themselves in new environments, often to the detriment of native ecosystems. Here are a few examples:

American mink

Introduced for fur farming, escapees quickly established wild populations across Europe. They have had a profound impact on local fauna, contributing to the decline of the European mink and certain bird species.

Grey squirrel 

Introduced to the United Kingdom and Italy from North America, the grey squirrel has been displacing the native red squirrel due in part to competition for food resources and the spread of the deadly squirrel pox virus.

Zebra mussel 

Originally from Eastern Europe, zebra mussels have spread across Europe’s freshwater bodies, attaching themselves in large numbers to hard surfaces. They significantly alter the ecosystems they invade by outcompeting native species for food and habitat.

Signal crayfish

This North American species was introduced to Europe for aquaculture in the 1960s. It has been spreading rapidly and outcompeting native crayfish, additionally spreading the crayfish plague, a disease deadly to native crayfish.

Giant hogweed 

This plant, native to Central Asia, is now found across Europe. It grows rapidly and outcompetes native vegetation. Its sap can cause severe burns on human skin.

Harlequin ladybird 

Originally from Asia, this ladybird has become one of the most invasive species in Europe, outcompeting native ladybirds and influencing the whole ecosystem by altering the distribution of resources.

Asian hornet

This invasive species from Asia preys on honeybees, causing significant damage to bee populations and potentially impacting pollination.

Water hyacinth 

This fast-growing plant from South America can completely cover waterways, blocking light and oxygen and causing declines in fish and other aquatic species.

Eastern grey squirrel 

Imported from North America, this squirrel has displaced the native red squirrel in many parts of the United Kingdom and Italy.


Originally from South America and brought to Europe for fur farming, this rodent damages aquatic ecosystems and contributes to soil erosion by burrowing.

These are just a few examples; unfortunately, the list of invasive species in the EU is much longer and continues to grow. Each of these species poses unique challenges to ecosystems and often requires unique strategies for management and control.


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