Multiple Stressors and Salamanders: Effects of an Herbicide, Food Limitation, and Hydroperiod

Amphibian populations can be affected adversely by multiple biotic and abiotic stressors that together can contribute to their local and global decline. We focused on the combined effects of food limitation, drying conditions, and exposure to possibly the most abundant and widely used herbicide in the world, atrazine. We used a factorial design to evaluate the effects of exposure to four ecologically relevant doses of atrazine (approximate measured doses: 0, 4, 40, and 400 μg/L), two food levels (limited and unlimited food), and two hydroperiods (presence or absence of a dry down) on the survival, life history, and behavior of the streamside salamander, Ambystoma barbouri, from the embryo stage through metamorphosis. In general, food and atrazine levels did not interact statistically, and atrazine affected dependent variables in a standard, dose-dependent manner. Exposure to 400 μg/L of atrazine decreased embryo survival and increased time to hatching. Drying conditions and food limitation decreased larva...