DOHM, M.R.*; MAUTZ, W.J.: Effects of ozone on marine toad thermoregulatory behavior and immune function
Ozone (O3) is a common air pollutant in many urban settings, and in the adjacent wildlife habitats, O3 levels frequently exceed the U.S. federal standard of 0.12 ppm. Ozone is a strong pulmonary irritant and causes a suite of thermoregulatory, metabolic, immunological, and respiratory tract inflammatory responses in humans and other mammals. However, the effects of O3 on other vertebrate groups are not known. Amphibians may be a sensitive model for elucidating the consequences of O3 exposure on biological systems. The skin of amphibians is a gas exchange organ and is therefore a respiratory membrane with direct exposure to O3 and other airborne pollutants. In initial studies with the marine toad (Bufo marinus), we found that water balance, thermal preferences, and immune function of toads were all adversely affected one day after a 4 hr exposure to 0.8 ppm O3 at 22 C. Compared to toads exposed to air, toads exposed to O3 lost more body mass (~4 g, adjusted mean) during exposure and selected lower body temperatures in a thermal gradient. O3 also impaired pulmonary immune function of toads. In a phagocytosis assay, pulmonary macrophages from O3-exposed toads consumed fewer microsphere test particles. Given that wilderness habitats adjacent to urban areas often receive relatively high levels of mixed air pollutants containing significant levels of O3, our results add to the growing list of potential explanations for regional and global declines of amphibian populations. Supported by a Minority Biomedical Research Support grant from the National Institute of Health (S06GM08073-26 subproject) to WJM.
