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FACILITATED INVASIONS: A NON-NATIVE FISH INCREASES SURVIVAL OF A NON-NATIVE ANURAN
Citation:
Adams, M. J., C. A. Pearl, R. B. Bury, AND A V. Nebeker. FACILITATED INVASIONS: A NON-NATIVE FISH INCREASES SURVIVAL OF A NON-NATIVE ANURAN. Presented at Joint Wildlife Society/American Fisheries Society Conference, Portland, OR, February 14-16, 2001.
Description:
The introduction of a variety of non-native gamefish to formerly fishless ponds and lakes represents one of the most widespread alterations of freshwater habitats in western North America. We hypothesized that introduced bluegill are facilitating the survival of introduced bullfrogs through an indirect effect mediated by dragonfly (Aeshnidae) larvae. Aeshnid larvae were capable of high predation rates on bullfrog larvae in laboratory experiments and reduced survival to zero in field enclosures with either native fish (red-side shiner) or no fish. Adding bluegill increased survival of bullfrog larvae from zero to 20% when aeshnids were present but had no effect when aeshnids were absent. In field surveys conducted in Oregon and Washington, bullfrog abundance was higher and predaceous macroinvertebrate abundance was lower when non-native fish were present. We conclude that non-native fish are facilitating the survival of bullfrog larvae and hypothesize that they are facilitating the invasion of bullfrogs. Both fish and bullfrogs can be detrimental to native amphibians, but we suggest that introduced fish should be a higher priority management concern than bullfrogs.