Invasive alien Crustacea: dispersal, establishment, impact and control.

The subphylum Crustacea includes the most successful species among aquatic alien invaders. The impacts of invasive alien crustaceans (IAC) are often substantial, due to the complex trophic role of most of these species leading to cascading effects throughout the invaded ecosystems. IAC also have the potential to cause a shift in the ‘keystone’ ecosystem functions, changing energy flux and nutrient cycles which together affect critical ecosystem services such as biodiversity, fisheries yield and water quality. Although no individual trait appears to be a good predictor of invasion success, a combination of some characteristics such as eurytolerance, omnivory and certain r-selected life-history traits results in a high probability of alien crustacean species becoming invasive. Both environmental factors, such as habitat heterogeneity in the invaded ecosystems, and evolutionary factors, such as adaptations to new environmental conditions, also play important roles during establishment. Therefore, individual environmental niche models, including genetic algorithm, have the highest likelihood of providing useful predictive information about invasion success and spread of alien Crustacea. Attempts to control IAC through biocides or mechanical removal have had mixed success in the past but a strategic combination of different methods may lead to some success in the future.