Indirect facilitation of an anuran invasion by non-native fishes

Authors: Michael J Adams; Christopher A Pearl; Richard B Bury
Contribution Number: 67


Positive interactions among non-native species could greatly exacerbate the problem of invasions, but are poorly studied and our knowledge of their occurrence is mostly limited to plant-pollinator and dispersal interactions. We found that invasion of bullfrogs is facilitated by the presence of coevolved non-native fish, which increase tadpole survival by reducing predatory macroinvertebrate densities. Native dragonfly nymphs in Oregon, USA caused zero survival of bullfrog tadpoles in a replicated field experiment unless a non-native sunfish was present to reduce dragonfly density. This pattern was also evident in pond surveys where the best predictors of bullfrog abundance were the presence of non-native fish and bathymetry. This is the first experimental evidence of facilitation between two non-native vertebrates and supports the invasional meltdown hypothesis. Such positive interactions among non-native species have the potential to disrupt ecosystems by amplifying invasions, and our study shows they can occur via indirect mechanisms.

Publication details
Published Date: 2003-03-13
Outlet/Publisher: Ecology Letters 6: 343-351
Media Format: .PDF

ARMI Organizational Units:
Pacific Northwest - Biology
Invasive Species; Management
Place Names:
Pacific Northwest
ecology; fish; introduced species; invasives
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