Identification of alien predators that should not be removed for controlling invasive crayfish threatening endangered odonates

Abstract

• 1.
  When multiple invasive species coexist in the same ecosystem and their diets change as they grow, determining whether to eradicate any particular invader is difficult because of complex predator–prey interactions.
• 2.
  A stable isotope food-web analysis was conducted to explore an appropriate management strategy for three potential alien predators (snakehead Channa argus, bullfrog Rana catesbeiana, red-eared slider turtle Trachemys scripta elegans) of invasive crayfish Procambarus clarkii that had severely reduced the densities of endangered odonates in a pond in Japan.
• 3.
  The stable isotope analysis demonstrated that medium- and small-sized snakeheads primarily depended on crayfish and stone moroko Pseudorasbora parva. Both adult and juvenile bullfrogs depended on terrestrial arthropods, and juveniles exhibited a moderate dependence on crayfish. The turtle showed little dependence on crayfish.
• 4.
  These results suggest that eradication of snakeheads risks the possibility of mesopredator release, while such risk appears to be low in other alien predators. Copyright © 2011 John Wiley & Sons, Ltd.