PARENT SESSION
Organized Oral Session 8: Contaminants in aquatic systems: Individual effects and community consequences.
Organizer(s): J Kerby and R Relyea
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 510b, Level 5, Palais des congrès de Montréal

The dose that keeps on giving: Terrestrial performance of juveniles in two habitat types after chronic contaminant exposure as tadpoles.

James, Stacy^*,1, Semlitsch, Raymond¹, ¹ University of Missouri-Columbia, Columbia, Missouri

ABSTRACT- The physical alteration and chemical contamination of the environment can cause changes in the abundance and diversity of amphibian populations. However, these factors are usually considered in isolation using single life stages. A study was conducted to determine the terrestrial performance of southern leopard frog (Rana sphenocephala) juveniles that had been chronically exposed to one of three concentrations of the heavy metal cadmium (0, 5, or 18 g/L) as tadpoles. Juveniles were reared in terrestrial enclosures within deciduous forest and open field habitats through their first growth season (summer to autumn). Terrestrial survival was higher in forests (73%) than in fields (54%), and there was a significant habitat by cadmium interaction. The trend for summer mass to increase with cadmium concentration was maintained through autumn, and individuals in the field sites were heavier than their counterparts in the forest. Growth rate was likewise significantly affected by habitat type and cadmium concentration. The forest sites had higher soil moisture and relative humidity, and cooler air temperatures, which should be beneficial to amphibians. These results suggest southern leopard frog juveniles experience higher survival in deciduous forest habitats, but that slower growth is a tradeoff under the conditions tested. Larval exposure to cadmium did not appear to have any detrimental latent effects, but instead conferred the advantage of a larger size at metamorphosis that remained through autumn. Efforts to manage this species should minimize the conversion of deciduous forests to open fields around aquatic breeding sites.

Key words: amphibian, contaminant, juvenile, terrestrial