As one of Europe’s five native crayfish species, the white clawed crayfish (Austropotamobius pallipes) has suffered a huge decline in numbers in the last couple of decades. This docile crustacean is usually found hiding under rocks in streams, rivers and lakes, only emerging at night to avoid predators. A fortnight ago it’s IUCN status was upgraded from ‘vulnerable’ to ‘endangered’ on the Red List of Threatened Species, with experts predicting it could be extinct within 30 years. It has recently been documented that 50 to 80% of the populations in England, Italy and France have disappeared in the last 10 years. What could be causing such a devastating loss in the U.K.?
Our river systems are undoubtedly one of the most diverse habitats found within the British Isles. They provide us with numerous benefits including areas for relaxation and recreation, they harbour high levels of biological diversity, act as natural flood management, provide water for consumption and irrigation, and act as corridors for the movement of nutrients and species in an otherwise fragmented landscape. However, our river systems are highly vulnerable habitats. Seasonal variations in hydrological processes render riparian habitats prone to high levels of disturbance which aid the invasion and colonisation of invasive plant species.
Himalayan balsam monoculture on the banks of the River Torridge, North Devon, UK (CABI)
The Global Invasive Species Programme (GISP) has recently published two publications on invasive species, Mainstreaming Gender into Prevention and Management of Invasive Species, and Invasive Species, Climate Change and Ecosystem-Based Adaption: Addressing Multiple Drivers of Global Change, both of which deserve a read. Both publications can be downloaded via the GISP website