PARENT SESSION
Oral Session 14: Reptiles and Amphibians I: Salamanders and Newts.
Presiding: K McCoy
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 136.

Prey availability limits growth of a predator in old growth but not regrowth.

Zaradic, Patricia^*,1, ¹ Biology Department, Philadelphia, PA, USA

ABSTRACT- Top-down models of community structuring assume predators are food-limited, but empirical tests of this assumption are rare. The effects of predation in structuring a prey community are likely to depend on the degree, and temporal and spatial scale, of food-limitation. Changes in abiotic variables between assemblages are likely to differentially affect a predator and its prey, thereby altering the degree of food-limitation and the resulting predator structuring of that prey community. Pacific giant salamander larvae (Dicamptodon tenebrosus) are abundant top predators in old growth forest streams of the Pacific Northwest. Logging has long-term detrimental effects, substantially reducing populations of this top predator. Taking advantage of the difference in habitat variables and population density at an old growth, and a previously logged, stream site, I tested the hypothesis that D. tenebrosus larvae are food limited in old growth as compared to regrowth. Individually marked salamander larvae were fed and growth compared with conspecifics in both an old growth and 40-year regrowth stream pool. Results of the enclosure-free field experiment and data from nearby long-term study sites suggest food availability may regulate populations of this top-predator in old growth but not regrowth forest streams.

Key words: salamander, predator, old growth, food-limited