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US Forest Service Research & Development
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Research Highlights

Individual Highlight

Water velocity tolerance in tadpoles of the foothill yellow-legged frog (Rana boylii):

Foothill yellow-tailed tadpoles. Sarah Kupferberg, U.C. BerkeleySnapshot : The effects of large magnitude flow fluctuations in rivers with dams, commonly referred to as pulsed flows, on tadpoles of Foothill Yellow-legged frog, Rana boylii were explored. The velocity conditions in habitats occupied by tadpoles were quantified and then experiments conducted to assess the tolerance to values at the upper limit of, and outside, the natural range.

Principal Investigators(s) :
Amy Lind 
Research Station : Pacific Southwest Research Station (PSW)
Year : 2011
Highlight ID : 379

Summary

We explored the effects of large magnitude flow fluctuations in rivers with dams, commonly referred to as pulsed flows, on tadpoles of the lotic-breeding Foothill Yellow-legged Frog, Rana boylii. We quantified the velocity conditions in habitats occupied by tadpoles and then conducted experiments to assess the tolerance to values at the upper limit of, and outside, the natural range. In laboratory flumes and field enclosures we mimicked the velocities observed during pulsed flows. In all experimental venues, the behavioral response of tadpoles was to seek refuge in the channel substrate when velocity increased. In a large laboratory flume, tadpoles moved freely at low water velocities (0-2 cm?s-1) and then sheltered among rocks when velocity increased. In a smaller scale laboratory flume, the median critical velocity was 20.1 cm?s-1. Critical velocity varied inversely with tadpole size, developmental stage, and proportion of time spent swimming. Velocities as low as 10 cm?s-1 caused tadpoles approaching metamorphosis to be displaced. In field mesocosm experiments, tadpoles exposed to repeated sub-critical velocity stress (5-10 cm?s-1) grew significantly less and experienced greater predation than tadpoles reared at ambient velocities. Responses to velocity manipulations were consistent among tadpoles from geographically distinct populations representing the three identified clades within R. boylii. The velocities associated with negative effects in these trials are less than typical velocity increases in near shore habitats when recreational flows for white water boating or peaking releases for hydroelectric power generation occur.

Forest Service Partners

External Partners

 
  • S. Kupferberg, UC Berkeley, V. Thill, Barnard College, Columbia University and S. Yarnell, UC Davis

Research Topics

Priority Areas

  • Wildlife and Fish
  • Watershed Restoration