Direct and indirect effects of dragonfly (Anax imperator) nymphs on green toad (Bufo viridis) tadpoles

Gil Stav, Burt P. Kotler, Leon Blaustein

Research output: Contribution to journalArticlepeer-review


We conducted an artificial pond experiment to assess the direct and indirect effects of predation on Bufo viridis tadpoles. We ran three treatments: free Anax (unrestrained predatory dragonfly nymph Anax imperator), caged Anax (non-consumptive effects), and control (no Anax). Anax showed both strong consumptive and non-consumptive effects on Bufo tadpoles. Free Anax eliminated all of the tadpoles within six days. Tadpoles preferred the shady side of the ponds. Caged Anax caused tadpoles to increase their spatial preferences. Tadpoles avoided the center of the pond, and in the presence of the caged predator, they were found in the center even less. Tadpoles also showed a strong preference for crowding together, and in the presence of a caged Anax, they tended to crowd more. Moreover, Bufo metamorphosed earlier and at a larger size in the caged Anax ponds, possibly by providing extra food resources due to the extra organic matter excreted by the predators.

Original languageEnglish
Pages (from-to)85-93
Number of pages9
Issue number1
StatePublished - Mar 2007

Bibliographical note

Funding Information:
Acknowledgements We thank Miguel Tejedo for critically reading and improving this manuscript. This study was partially funded by a U.S.-Israel Binational Science Foundation grant 98–390 awarded to Leon Blaustein and Marc Mangel. Tadpoles and dragonfly nymphs used in this study were collected under Israel Nature and Parks Authority permit number 1998/3902.


  • Artificial ponds
  • Distribution
  • Predation
  • Risk of predation

ASJC Scopus subject areas

  • Aquatic Science


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