TY - JOUR T1 - Hellbender Salamanders (Cryptobranchus alleganiensis) Exhibit an Ontogenetic Shift in Microhabitat Use in a Blue Ridge Physiographic Region Stream JF - bioRxiv DO - 10.1101/139766 SP - 139766 AU - K. A. Hecht AU - M. J. Freake AU - M. A. Nickerson AU - P. Colclough Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/05/18/139766.abstract N2 - Organisms that experience large changes in body size during the life span often exhibit differences in resource use among life stages. Ontogenetic shifts in habitat use reduce intraspecific competition and predation and are common in lotic organisms. Although information on the immature life stages of the Hellbender (Cryptobranchus alleganiensis) is limited, this aquatic salamander exhibit’s ontogenetic shifts in habitat use in some streams, with adults sheltering under large rocks and larvae utilizing interstitial spaces of gravel beds. Due to the geomorphology of Little River, Tennessee, however, limited interstitial spaces within the gravel are filled with sand. Therefore we quantified microhabitat parameters for three life stages of Hellbenders (larvae, sub-adult, adult) to determine if an ontogenetic shift in microhabitat occurred in this location. We found no significant differences in stream substrate at capture sites among the stages, but there was a positive correlation between rock shelters underlain with very coarse gravel and overall Hellbender occupancy. Although we found no difference in water quality parameters and streambed particle size among the stage classes at the site of capture, there was a significant difference in the average shelter size among all stages, with larvae utilizing the smallest shelters. As the smaller rocks utilized by larvae in Little River could be less secure shelter than the larger rocks used by adults, mortality may be higher in young Hellbenders due to a potential increase in overall predation risk and susceptibility to flooding. Based on these results, future Hellbender research and conservation efforts should consider differences in life stage habitat use as well as specific stream particle classes. ER -