M9 AM Ecotoxicology of Reptiles
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 339-340

(DUR-1117-752799) Effects of a cholinesterase-inhibitor on energy acquisition, energy expenditure, and locomotor performance in a reptile.

DuRant, S¹, Hopkins, W¹, Talent, L², ¹ University of Georgia, Savannah River Ecology Laboratory, Aiken, SC, USA² Oklahoma State University, Stillwater, OK, USA

ABSTRACT- Contaminant exposure has been implicated as a possible cause for the decline of reptile populations. However, exceedingly few studies have examined reptilian responses to contaminants under controlled conditions. In this study we examined the effects sublethal doses of a widely used cholinesterase-inhibiting pesticide, carbaryl, had on three fitness-related traits: energy acquisition, energy expenditure, and locomotor performance. We hypothesized that carbaryl would increase an organism's energy expenditure (i.e., oxygen consumption and carbon dioxide production), decrease energy acquisition, and decrease locomotor performance. We administered varying doses of carbaryl (0, 2.5, 25, and 250g/g) via oral gavage to western fence lizards (Sceloporus occidentalis). To quantify the effects of carbaryl on energy acquisition and allocation, we monitored respiration and food consumption for 48-96 hours post-exposure. To determine whether carbaryl affected terrestrial and arboreal locomotor performance we quantified the maximum sprint velocity of lizards at multiple time points up to 96 hours post-exposure. The highest doses of carbaryl caused a 17% increase in basal metabolic rate compared to controls, but a carbaryl-induced reduction in activity resulted in a net 18% decrease in total energy expenditure. During this same time interval, lizards receiving the highest dose exhibited a 26% decrease in food consumption compared to controls. The highest doses of carbaryl also resulted in an 8-10 % decrease in sprint velocity and a 26-40% decrease in arboreal velocity in our highest dose group compared to controls. In all cases, lizards appear to have recovered by 96hrs. This study indicates that acute exposure to carbaryl could increase susceptibility of lizards to predation due to decreased locomotor performance and that normal activity patterns and energy balance could be disrupted. Future studies are needed to assess whether repeated exposures could have implications for survival or energy allocation to important life-history characteristics (i.e., growth and reproduction).

Key words: reptile, carbaryl, performance, respiration