Effects of ozone on evaporative water loss and thermoregulatory behavior of marine toads (Bufo marinus)

Ozone (O-3) is a strong pulmonary irritant and causes a suite of respiratory tract inflammatory responses in humans and other mammals. In addition to lung injury, rodents exposed to O-3 exhibit a pronounced decrease in core body temperature at rest, which may offer a protective effect against O-3 damage. The effects of O-3 On Other vertebrates have not been studied. Compared to individuals exposed to air (N = 34), Bufo marinus toads exposed to O-3 (N = 32) for 4 h lost 3.78 g body mass (adjusted mean from analysis of covariance, body mass mean +/- SD, 90.1 +/- 21.90 g). We tested the thermoregulatory responses of 22 toads in a thermal gradient 1, 24, and 48 h after 4-h exposure to air (N = 11) or 0.8 ppm O-3 (N = 11). Individual toad thermal preferences were also significantly repeatable across all trials (intraclass correlation = 0.86, P < 0.001). We did not observe a direct effect of O-3 exposure on the preferred body temperatures (PBT) of toads. However, O-3 exposure did have an indirect effect on selected temperatures. Ozone-exposed toads with higher evaporative water loss rates, in turn, also selected lower PET, voluntary minimum, and voluntary maximum temperatures 24 h post-exposure. Ozone exposure may thus alter both water balance and thermal preferences in anuran amphibians. (C) 2001 Academic Press.