Invasive alien species pose major global threats to Nature, economies, food security and human health according to an IPBES report
The severe global threat posed by invasive alien species is underappreciated, underestimated, and often unacknowledged.
According to a major new report by the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), more than 37,000 alien species have been introduced by many human activities to regions and biomes around the world.
This conservative estimate is now rising at unprecedented rates.
More than 3,500 of these are harmful invasive alien species – seriously threatening Nature and Nature’s contribution to people and good quality of life.
Too often ignored until it is too late, invasive alien species are a significant challenge to people in all regions and in every country.
Approved in Bonn, Germany, by representatives of the 143 member states of IPBES, the Assessment Report on Invasive Alien Species and their Control finds that alongside dramatic changes to biodiversity and ecosystems, the global economic cost of invasive alien species exceeded $423bn (~£337bn) annually in 2019, with costs having at least quadrupled every decade since 1970.
Professor Helen Roy (United Kingdom), co-chair of the assessment with Professor Anibal Pauchard (Chile) and Professor Peter Stoett (Canada), said: “Invasive alien species are a major threat to biodiversity and can cause irreversible damage to nature, including local and global species extinctions, and also threaten human wellbeing.”
The authors of the report emphasise that not all alien species become invasive – invasive alien species are the subset of alien species that are known to have become established and spread, which cause negative impacts on Nature and often also on people.
About 6% of alien plants; 22% of alien invertebrates; 14% of alien vertebrates; and 11% of alien microbes are known to be invasive, posing major risks to Nature and to people.
People with the greatest direct dependence on Nature, such as Indigenous Peoples and local communities, are found to be at even greater risk.
More than 2,300 invasive alien species are found on lands under the stewardship of Indigenous Peoples – threatening their quality of life and even cultural identities.
While many alien species were historically introduced on purpose for their perceived benefits to people, the IPBES report finds that the negative impacts of those that do become invasive are enormous for nature and people.
Pauchard said: “Invasive alien species have been a major factor in 60% and the only driver in 16% of global animal and plant extinctions that we have recorded, and at least 218 invasive alien species have been responsible for more than 1,200 local extinctions.
“In fact, 85% of the impacts of biological invasions on native species are negative.”
Examples of such impacts include the ways that North American beavers (Castor canadensis) and Pacific Oysters (Magallana gigas) change ecosystems by transforming habitats – often with severe consequences for native species.
Nearly 80% of the documented impacts of invasive alien species on Nature’s contributions to people are also negative – especially through damage to food supplies – such as the impact of the European shore crab (Carcinus maenas) on commercial shellfish beds in New England and the damage caused by the Caribbean false mussel (Mytilopsis sallei) to locally important fishery resources in India.
Similarly, 85% of documented impacts negatively affect people’s quality of life – for instance through health impacts, including diseases such as malaria, Zika and West Nile Fever, spread by invasive alien mosquito species like Aedes albopictus and Aedes aegyptii.
Pauchard said: “It would be an extremely costly mistake to regard biological invasions only as someone else’s problem.
“Although the specific species that inflict damages 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.”
Roy added: “The future threat from invasive alien species is a major concern; 37% of the 37,000 alien species known today have been reported since 1970 – largely caused by rising levels of global trade and human travel.
“Under ‘business-as-usual’ conditions, we project that total numbers of alien species will continue to increase in this way.”
On a more positive note, the report highlights that future biological invasions, invasive alien species, and their impacts, can be prevented through effective management and more integrated approaches.
Pauchard said: “The good news is that, for almost every context and situation, there are management tools, governance options and targeted actions that really work.
“Prevention is absolutely the best, most cost-effective option – but eradication, containment and control are also effective in specific contexts.
“Ecosystem restoration can also improve the results of management actions and increase the resistance of ecosystems to future invasive alien species.
“Indeed, managing invasive alien species can help to mitigate the negative effects of other drivers of change.”
Prevention measures – such as border biosecurity and strictly enforced import controls – are identified by the report as having worked in many instances, such as the successes achieved in Australasia in reducing the spread of the brown marmorated stink bug (Halyomorpha halys).
Preparedness, early detection and rapid response are shown to be effective at reducing rates of alien species establishment, and to be especially critical for marine and connected water systems.
The PlantwisePlus programme, assisting smallholder farmers in Africa, Asia and Latin America is spotlighted by the report as a good example of the importance of general surveillance strategies to detect new alien species.
Eradication has been successful and cost-effective for some invasive alien species, especially when their populations are small and slow-spreading, in isolated ecosystems such as islands.
Some examples of this are in French Polynesia where the black rat (Rattus rattus) and rabbit (Oryctolagus cuniculus) have been successfully eradicated.
The report indicates that eradication of alien plants is more challenging due to the length of time that seeds may lie dormant in soil.
The authors add that successful eradication programmes depend on, amongst other elements, the support and engagement of stakeholders and Indigenous Peoples and local communities.
Image 1: The North American beaver can negatively impact ecosystems by transforming habitats. Credit: Cephas, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons.
Image 2: The invasive black rat has been eradicated from some areas in French Polynesia. Credit: Bernard DUPONT from FRANCE, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons.