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Article
Effects of Natural Flooding and Manual Trapping on the Facilitation of Invasive Crayfish-Native Amphibian Coexistence in a Semi-arid Perennial Stream
Journal of Arid Environments (2013)
  • Lee Kats, Pepperdine University
  • Gary Bucciarelli, University of California - Los Angeles
  • Thomas L. Vandergon, Pepperdine University
  • Rodney L. Honeycutt, Pepperdine University
  • Evan Mattiasen, Pepperdine University
  • Arthur Sanders, Pepperdine University
  • Seth P. D. Riley, National Park Service
  • Jacob L. Kerby, University of South Dakota
  • Robert N. Fisher, U.S. Geological Survey
Abstract
Aquatic amphibians are known to be vulnerable to a myriad of invasive predators. Invasive crayfish are thought to have eliminated native populations of amphibians in some streams in the semi-arid Santa Monica Mountains of southern California. Despite their toxic skin secretions that defend them from native predators, newts are vulnerable to crayfish attacks, and crayfish have been observed attacking adult newts, and eating newt egg masses and larvae. For 15 years, we have observed invasive crayfish and native California newts coexisting in one stream in the Santa Monica Mountains. During that period, we monitored the densities of both crayfish and newt egg mass densities and compared these to annual rainfall totals. After three seasons of below average rainfall, we reduced crayfish numbers by manual trapping. Our long-term data indicated that crayfish did not fare well in years when rainfall is above the historic average. This invasive predator did not evolve with high velocity streams, and observations indicated that southern California storm events washed crayfish downstream, killing many of them. Newts exhibit increased reproduction in years when crayfish numbers were reduced. A comparison with a nearby stream that does not contain crayfish indicated that newt reproduction positively responded to increased rainfall, but that fluctuations were much greater in the stream that contains crayfish. We suggest that rainfall patterns help explain invasive crayfish/newt coexistence and that management for future coexistence may benefit from manual trapping.
Keywords
  • Amphibians,
  • conservation,
  • flooding,
  • invasive species,
  • Southern California,
  • Taricha torosa
Publication Date
November, 2013
Citation Information
Lee Kats, Gary Bucciarelli, Thomas L. Vandergon, Rodney L. Honeycutt, et al.. "Effects of Natural Flooding and Manual Trapping on the Facilitation of Invasive Crayfish-Native Amphibian Coexistence in a Semi-arid Perennial Stream" Journal of Arid Environments Vol. 98 (2013)
Available at: http://works.bepress.com/lee_kats/11/