The 'dirty dozen' aquatic invaders of the British Isles

Researchers use socio-economic factors as well as occurrence data to model the risk of invasions from twelve alien aquatic species in Great Britain and Ireland.

Data resources used via GBIF : 12 invasive species modelled
Hemimysis anomala. Credit: S. Pothoven, GLERL, CC-BY-NC 2.0

Hemimysis anomala. Credit: S. Pothoven, GLERL, CC-BY-NC 2.0

This study from the Aquatic Zoology Group of Cambridge University set out to identify invasive species that posed the highest risk to aquatic biodiversity in Great Britain and Ireland. Starting with a list of 12 invertebrates, fish and plants known to be ‘potential aquatic invaders’ the researchers used both environmental and socio-economic factors to establish which areas were at greatest risk of invasion from which species.

To generate models for the study, the researchers obtained data on the global occurrence of all 12 species through GBIF, Fishbase, the United States Geological Survey and the Atlas Flora Europaea. Environmental factors such as climate, altitude and geology were used to determine which areas of Great Britain and Ireland would be most suitable for the invaders to thrive.

An innovation of the study was to integrate socio-economic factors to improve the prediction of invasion risk. For example, population density, a ‘human influence index’ and the closeness to major ports can predict where aquatic invaders are most likely to be introduced from activities such as shipping, sport fishing, canal building and the pet trade.

The study concluded that the threat from aquatic invasive species was especially high in southeast England, with five species of special concern: the killer shrimp (Dikerogammarus villosus), bloody red mysid (Hemimysis anomala), both from the Black Sea/Caspian region; the water primrose (Ludwigia grandiflora); and two crayfish species from Central America (Procambarus clarkii and P. fallax).

The authors note that including socio-economic factors can improve prediction of areas at risk of multiple invasions and help target limited resources for prevention and control.

See press release from British Ecological Society.


Gallardo, B. & Aldridge, D.C., 2013. The “dirty dozen”: socio-economic factors amplify the invasion potential of 12 high-risk aquatic invasive species in Great Britain and Ireland C. Frid, ed. Journal of Applied Ecology. Available at: