Print PagePristine habitats are declining worldwide. This has led to more populations persisting in disturbed environments. Heavy metals in the water can be lethal to amphibians and delay development, but the effects of metals on amphibian behavior is poorly understood. Due to abandoned zinc and lead mines, elevated levels of cadmium (Cd) are found in the aquatic systems in north east Oklahoma. Cadmium inhibits olfaction in fish and we hypothesized it would do the same in tadpoles. We tested how Cd levels in the water altered the predator avoidance behaviors of southern leopard frog (Rana sphenocephala) tadpoles. Tadpoles use conspecific alarm cues to detect the presence of predators. We exposed tadpoles to various concentrations of Cd and alarm cues from dragonfly (Anax sp.) nymphs to see if sub-lethal levels of Cd in the water prevent tadpoles from detecting the alarm cues. To test if tadpole populations have adapted to Cd contamination these tests were conducted on tadpoles collected from ponds that have elevated Cd levels and results were compared to tests on tadpoles from an environment without Cd.
Results/Conclusions
Rana sphenocephala tadpoles reduce activity when they detect predators. The higher levels of Cd reduced the activity of tadpoles even before alarm cues were added. With this initial change of behavior accounted for tadpole activity did not decrease and even increased in tadpoles that were exposed to the highest concentrations of Cd. At high Cd concentrations tadpoles were unable to detect the alarm cues and continued to actively swim.
