Impact of chaparral wildfire-induced sedimentation on oviposition of stream-breeding California newts (Taricha torosa) |
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Authors: | Seth C Gamradt Lee B Kats |
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Institution: | (1) Natural Science Division, Pepperdine University, Malibu, CA 90263, USA email: lkats@pepperdine.edu, ML |
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Abstract: | We examined the effects of chaparral wildfire on stream-breeding California newts (Taricha torosa) in a 750-m stretch of a perennial Santa Monica Mountain stream (Los Angeles County). Detailed field surveys of 1992 and
1993 established the composition (run, riffle, pool) of this habitat and determined the oviposition sites of newts. We also
quantified California newt egg mass density and estimated the density of newt adults. A chaparral wildfire burned the entire
study site on 2 November 1993. Using the same methods, we collected field survey data in 1994 and 1996. Erosion following
the 1993 wildfire produced major changes in stream morphology and composition. Pools and runs represented approximately 40–50%
of pre-fire stream area. In the spring following the fire, the stream consisted of less than 20% run and pool. Pools that
did remain were often smaller and shallower. The average density of adult California newts did not differ among years. The
total number of newt egg masses observed in the spring after the fire was approximately one-third of egg mass counts from
pre-fire surveys. Most California newt egg masses were laid in pools and runs; California newts prefer deeper slow-moving
water. We conclude that fire-induced landslides and siltation have eliminated pools and runs, thus reducing the amount of
habitat suitable for oviposition. Habitat alterations caused by fire likely account for the observed reduction of egg masses
at the stream.
Received: 11 June 1996 / Accepted: 18 December 1996 |
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Keywords: | Amphibians Fire ecology Oviposition Stream morphology Taricha torosa |
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