ABSTRACT
Concern over the localized reduction of amphibian populations and the potential role that chemical stressors were playing in these declines was expressed nearly 30 years ago (Gibbs et al. 1971; Birge et al. 1980; Bury 1999), an observation recently revisited for reptiles (Gibbons et al. 2000). However, it has only been over the last decade that amphibians, and to a lesser extent reptiles, have been recognized as vertebrates truly unique from other terrestrial wildlife and the fishes. The burgeoning interest in the ecotoxicology of the herpetofauna has been driven in part by their continued population declines at a global scale and a growing appreciation that terrestrial wildlife such as birds and mammals and aquatic vertebrates such as fish may not adequately represent contaminant exposure experienced by amphibians and reptiles during the various phases of their life cycles. For most amphibians, this includes laying permeable eggs in water, an aquatic larval stage, a physiologically demanding period of metamorphosis from larva to juvenile, and an adult stage that occurs in both aquatic and terrestrial habitats. Even more recently, the importance of reptiles as ecological receptors in both aquatic and terrestrial habitats has been recognized. While lacking the distinctly bimodal life cycle seen in most amphibians, the long lives, philopatric tendencies, and for some species, amphibious lifestyles exhibited by reptiles may expose them to a variety of contaminants over very long time periods (Sparling et al. 2000a). The continuing increase in ecotoxicological research activities with herpetofauna has supported synthesis publications such as Sparling et al. (2000b), Linder et al. (2003a, 2003b), Campbell and Campbell (2000, 2001), and Gardner and
4.1 Historic Developments: Amphibians and Reptiles in Ecotoxicology .................................... 70 4.1.1 Amphibians ................................................................................................................. 70 4.1.2 Reptiles ....................................................................................................................... 70
4.2 Contaminant Exposure Pathways for Amphibians and Reptiles ............................................ 71 4.3 Toxicity Assessment: Laboratory Studies............................................................................... 72
4.3.1 Toxicity Tests Using Amphibians ............................................................................... 72 4.3.2 Toxicity Tests Using Reptiles......................................................................................80
