Meeting Abstract
We monitored the physiological health and stress response of tadpoles using non-invasive water-borne assays to measure the stress hormone, corticosterone (CORT). We performed an adrenocorticotropic hormone (ACTH) challenge and additional experiments to explore repeatability, recovery time from stress, and optimal rearing methods for Rio Grande Leopard frog, Rana berlandieri, tadpoles. Tadpole CORT release rates were higher after ACTH injections, validating water-borne hormone methods. We then examined the recovery time for water-borne CORT release rates after exposure to an external stressor (agitation). CORT began to decline after 2h and had recovered after 6h indicating that it is important to wait an extra hour (or up to 6hrs) if you want to avoid measuring the initial stress response. We also examined CORT and repeatability using water-borne hormones from tadpoles reared individually vs isolated in groups. We then examined whether these tadpoles show an acute stress response after exposure to agitation. Individuals isolated in groups showed hypothalamus-pituitary-interrenal axis (HPI) activity in response to a stressor and higher CORT release rates on D7. These individuals also lost mass by D7, whereas individuals reared alone did not. Repeatability was high for both treatments. These results indicate that either rearing method is viable but the two methods differ in their physiological costs. We show that the water-borne hormone method allows for repeated measures from individuals when the experiment is appropriately designed to consider social behavior of the species. This will be useful in management and health assessment of wild and captive populations of R. berlandieri.
