BELDEN, L.K.*; WINGFIELD, J.C.; KIESECKER, J.M.; Virginia Polytechnic Institute and State University; University of Washington; Pennsylvania State University: Corticosterone and growth in larval amphibians (Rana sylvatica, Ambystoma jeffersonianum and Scaphiopus holbrooki)

In amphibians, corticosterone (the main glucocorticosteroid) has a role in both responses to environmental perturbations and in regulating larval growth and development preceding metamorphosis. As such, corticosterone may be mediating some of the well-documented effects that environmental stressors have on larval amphibian growth and development. In a series of studies, we began to explore this potential link for several species of amphibians native to the Eastern U.S. We completed confinement stress series on larvae of four species of amphibians in natural/semi-natural conditions: Wood frogs (Rana sylvatica), Spring peepers (Pseudacris crucifer), Jefferson�s salamanders (Ambystoma jeffersonianum) and Eastern spadefoot toads (Scaphiopus holbrooki). Three of the species had a typical vertebrate response of increasing corticosterone with increased time of confinement. However, Eastern spadefoot toads, which have a very short developmental period prior to metamorphosis, did not show any increase in corticosterone over an hour of confinement. In addition, we treated 3 of the species (R. sylvatica, A. jeffersonianum, S. holbrooki) with low doses (0.001 μM and 0.01 μM) of corticosterone in the laboratory and examined effects on growth. While we were successful in raising baseline corticosterone levels with our high dose of corticosterone, this did not translate into changes in mean larval growth for any of the three species.