Staggering cost of invasive species worldwide revealed

Scientists estimate that each year sees another 200 invasive species become established worldwide. The negative effects of such species are wide ranging, from predation of nesting seabirds by rodents that have been brought to islands to the intensification of wildfires by invasive grasses, as seen in Hawaii this August.

Professor Aníbal Pauchard, one of the lead researchers behind the UN's latest Invasive Alien Species Report, published in early September, said: "It would be an extremely costly mistake to regard biological invasions only as someone else's problem. Although the specific species that inflict damage vary from place to place, these are risks and challenges with global roots but very local impacts facing people in every country, from all backgrounds and in every community — even Antarctica is being affected."

American Mink is well known as a harmful invasive species in Britain, where it has had an impact on Water Vole populations (Frank Golding).

The assessment, produced by 86 experts including scientists and indigenous communities, has been four-and-a-half years in the making. In early September, it was approved by governments in Bonn after being put forward by the UN's Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).

Governments had requested more research into the impacts of invasive species after a 2019 report showed that one million species were at risk of extinction worldwide, with invasive species being behind 40% of all recorded animal extinctions.

Biological invasions have risen in their cost by 400% each decade and the authors predicted that the rise would continue. The authors listed the Americas as hosting 34% of invasive species reports, with Europe and Central Asia having 31%, Asia Pacific 25% and Africa a comparatively low 7%.

The 'top three' invasive species worldwide are Black Rat, Water Hyacinth (an aquatic plant native to South America) and a flowering shrub in the genus Lantana.

Professor Helen Roy, lead researcher for the report, said: "One of our real concerns is the loss of the uniqueness of communities of life. As we see more invasive species around the world, we start to see communities looking more similar. Of course, we have concerns about the functioning of those ecosystems and their resilience. Very sadly, the example of Hawaii is one to present as an example of ways in which we’re seeing this worsening and interactions among these global drivers of biodiversity loss."

Fighting the spread of invasive species was agreed as a target last December at COP15 in Montreal. The authors of the report detailed a range of tools to reduce the threat of alien species, such as eradication programmes on islands, which they say have shown an 88% success rate.

However, the report advised a shift in focus to prevention of the establishment of alien species, instead of allowing expensive eradication programmes to become necessary.

Professor Pauchard said: "We want to highlight that the thing that works the best is prevention. That's the main message. It’s much more cost-effective to prevent the introduction of invasive species such as taking biosecurity measures, border controls and risk analysis of non-native species that are being introduced intentionally."

Although some countries, such as New Zealand, have ambitious policies on the control of non-native species, the report found that 84% of countries have no relevant regulations or legislation to control the spread.

The report can be read online here.