title: Lethal and sublethal effects of chronic cadmium exposure on northern leopard frog (Rana pipiens) tadpoles.
abstract: Data on the chronic effects of cadmium on amphibians are lacking in spite of widespread anthropogenic contamination of terrestrial and aquatic systems. We exposed embryos and tadpoles of northern leopard frogs (Rana pipiens) to Cd (control, 0.25, 5.0, and 20.0 microg/L as CdCl2, nominal concentrations) in a static renewal system from embryonic stages to complete tail resorption. Survival of embryos (Gosner stage [GS] 17-25) was greater than 97% in all treatments. Tadpole survival was negatively correlated with dose and was significantly reduced in the 5.0 and 20.0 microg/L treatments compared with controls. Tadpole survival was greater than 80% through GS 42, forelimb emergence, for all other treatments. Tadpoles exposed to 0.25 and 5.0 microg/L exhibited increased growth by week 11; tadpoles exposed to 5.0 microg/L were significantly younger at forelimb emergence. Whole-tadpole body burdens of Cd were positively correlated with increasing Cd treatments. Cadmium was shown to alter growth and development in a native amphibian species at ecologically relevant concentrations. The existing chronic water quality criterion for Cd appears to be protective of amphibians. However, additional studies with other chemicals are needed to further explore the potential for adverse effects of contaminants on the complex life cycle of amphibians.
authors.affiliation: Department of Animal Sciences, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. jasongross@wisc.edu
authors.forename: Jackson A
authors.initials: JA
authors.lastname: Gross
authors.forename: Te-Hao
authors.initials: TH
authors.lastname: Chen
authors.forename: William H
authors.initials: WH
authors.lastname: Karasov
mesh_terms: D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D007814:Larva / Q000187:drug effects*; D008675:Metamorphosis, Biological; D011894:Rana pipiens / Q000254:growth & development*
chemical_list: D002104:Cadmium