Functional relationships among selenium concentrations in the diet, target tissues, and nondestructive tissue samples of two species of snakes

Abstract

Nondestructive sampling methods, such as removal of feathers for contaminant analysis, are desirable in ecological monitoring programs that seek to minimize the impacts of harvesting organisms. Although many reptiles are declining worldwide, nondestructive sampling techniques seldom have been employed for assessing contaminant exposure in these organisms. In this study, we examined the utility of nondestructive tissue sampling for assessing Se exposure in reptiles. We describe the functional relationships among dietary Se concentrations, target tissue Se concentrations, and Se concentrations in nondestructive tissue samples (blood and tail tissue biopsy) in two species of snakes that had been exposed to Se under very different experimental protocols. Using nonlinear regression, we found strong positive correlations (r2 > 0.92) in all comparisons among Se concentrations in nondestructive tissues, diet, and target tissues. Moreover, equations describing these relationships can be used to estimate concentrations of Se in diet and target organs, from known concentrations of Se in nondestructive tissue samples. Although the current paucity of toxicity data on reptiles precludes tests of our models, we demonstrate how the equations describing these relationships might be used to make predictions about Se accumulation in target organs for risk assessment. Future studies on reptiles that examine these relationships under different Se exposure conditions, and those that document physiological responses of reptiles to various concentrations of Se, will help to refine our models and test their efficacy for predicting health risk.