Oral deformities in several species of frogs from the Savannah River Site, USA

Tadpoles of seven species of frogs from 22 wetlands on the Savannah River Site in South Carolina, USA, were examined to assess the prevalence of mouth-part deformities and axial skeletal deformities. Species examined included southern toad (Bufo terrestris), pine woods treefrog (Hyla femoralis), spring peeper (Pseudacris crucifer), southern chorus frog (P. nigrita), ornate chorus frog (P. ornata), bronze frog (Rana calmitans), and southern leopard frog (R. utricularia). Of the 4,335 tadpoles examined in 1997 and 1998, 6% exhibited mouth-part deformities and none exhibited axial skeletal deformities. However, significant interspecific differences existed for both prehind-limb and posthind-limb developmental stages. The highest percentage of deformities in prehind-limb stage occurred in spring peeper (27%), ornate chorus frog (29%) and bronze frog (33%), and the lowest percentage occurred in southern toad (5.5%) and southern chorus frog (4.8%). The frequency of mouth deformities decreased from the prehind- to posthind-limb developmental. stage for six of seven species and was significant for southern toad and ornate chorus frog. Differences existed in the percent of mouth-part deformities among species in the same wetland and among wetlands for two species (southern toad and southern leopard frog). Among southern toads, mouth-part deformities increased with increasing hydroperiod length. Oral deformities may lead to lowered feeding success and lowered survival of tadpoles, resulting in a lower percentage of deformities in the posthind-limb stage.