Why are invasive alien species a problem?

Invasive Alien Species (IAS) are species that are accidentally or intentionally introduced outside their natural range and become a serious issue where established. Throughout Earth history, species movements have naturally occurred around the world. However, nowadays, globalisation, intensified international commerce of animals and plants, transport and tourism have led to an unprecedented number of species entering and potentially invading new ranges. For instance, the recent regional assessment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) for Europe and central Asia demonstrates that IAS have increased in number for all taxonomic groups across all the sub regions of Europe and Central Asia.


The issue of biological invasions represents one of the main drivers of biodiversity loss worldwide alongside other human-induced threats such as over-exploitation, habitat loss and climate change. These invaders disrupt well-established existing communities and ecosystems as they can alter ecosystem functions, native species diversity and abundance, notably due to predation or increased competition for resources. They also have the potential to carry and spread diseases.  obj 194


obj 195

The presence of IAS can also have strong socio-economic implications. IAS can have direct economic impacts through potential damage to natural resources based businesses such as agricultural productivity, fisheries, and forestry. Associated costs for the control and management of IAS are also tremendous. For instance, economic losses and expenses for the management of IAS in Europe have been estimated by the Institute for European Environmental Policy (IEEP) to € 20 billion a year. While estimated costs probably remain underestimated, they also appear to triple every decade. 

IAS can also pose a threat to human health, well-being and activities by being disease vectors or poisonous to humans and by impeding recreational activities. 


In response to this growing problem, the European Union and the Member States have put in place a number of preventive and management measures. For example, the European regulation on invasive species has been established with the aim to curb the phenomenon on a continental scale through the development of a coordinated EU-wide framework for actions to prevent, minimise and mitigate the negative impact of IAS.