Andree Gendron, Quebec, Canada

Waves of drastic decline of amphibian populations in several parts of the world, although controversial, have recently raised a general concern about the vulnerability of this group of vertebrates to anthropogenic stressors. Because of the breadth of geographical area affected by declines, the widespread contamination of the environment has been initially suspected to be a direct cause of population losses although evidence to support this claim is so far limited. In addition to being directly linked to dieoffs, the contaminants might impact on the physiological integrity of individuals hence contributing, as part of multifactorial stress, to build up the pressure exerted on populations of amphibians.

The present research was undertaken with the primary objective of detecting in the mudpuppy (Necturus maculosus), potential contaminants-induced changes at the physiological, individual and/or population level. The issue was addressed mainly by comparing populations of mudpuppy exposed in the wild to different degree of contamination by chlorinated hydrocarbons and other chemicals. The salamanders were sampled at 9 locations along the St. Lawrence and Ottawa rivers in Québec and Ontario. Some of the aspects examined include sex steroid levels, fecundity, gonado-somatic index, prevalence of developmental defects in the population, responsiveness to stressors as well as growth rate, age distribution and relative abundance. The mudpuppy (Necturus maculosus) is a strictly aquatic salamander widely distributed in many rivers of Eastern North America. This salamander is a long-lived species (>25 years) and a bottom-feeder relying partly on fish for its diet, making it susceptible to the adverse effects of long term exposures to lipophilic contaminants. Available data on movement behavior suggest that the mudpuppy is sedentary thus reflecting the contamination status of a restricted area.

Conference abstracts

Functional challenge of the corticosterone-producing axis in populations of an aquatic salamander exposed to organochlorines.

Impact of reproductive and developmental toxicants on wild populations of mudpuppy in Quebec and Ontario.