A logical starting point for developing priorities for lizard and snake ecotoxicology: A review of available data

Abstract

Reptiles, specifically lizards and snakes, usually are excluded from environmental contamination studies and ecological risk assessments. This brief summary of available lizard and snake environmental contaminant data is presented to assist in the development of priorities for lizard and snake ecotoxicology. Most contaminant studies were not conducted recently, list animals found dead or dying after pesticide application, report residue concentrations after pesticide exposure, compare contaminant concentrations in animals from different areas, compare residue concentrations found in different tissues and organs, or compare changes in concentrations over time. The biological significance of the contaminant concentrations is rarely studied. A few recent studies, especially those conducted on modern pesticides, link the contaminant effects with exposure concentrations. Nondestructive sampling techniques for determining organic and inorganic contaminant concentrations in lizards and snakes recently have been developed. Studies that relate exposure, concentration, and effects of all types of environmental contaminants on lizards and snakes are needed. Because most lizards eat insects, studies on the exposure, effects, and accumulation of insecticides in lizards, and their predators, should be a top priority. Because all snakes are upper-trophic-level carnivores, studies on the accumulation and effects of contaminants that are known to bioaccumulate or biomagnify up the food chain should be the top priority.

High levels of maternally transferred mercury do not affect reproductive output or embryonic survival of northern watersnakes (Nerodia sipedon)

“…Contaminants are among the six suspected contributors to global reptile declines, but few studies have examined contaminant exposure, maternal transfer, or associated effects in this class of vertebrates [10,11]. Among reptiles, snakes are especially overlooked, with relatively scant contaminant information available for only six of the 15 families [11].…”

“…Among reptiles, snakes are especially overlooked, with relatively scant contaminant information available for only six of the 15 families [11]. Snakes feed at high trophic levels and exhibit several ecological and lifehistory traits that increase their susceptibility to bioaccumulation of Hg and other contaminants [12].…”

Peer Reviewed: Wildlife Toxicology Revisited

“…Because of declining populations and the discovery of malformations in amphibians and reptiles, they have received much attention from the general public and biologists in the past decade (19). Numerous studies have indicated dramatic reductions in amphibian populations worldwide, with explanations such as climatic change; parasitic, bacterial, or viral infections; and increased predation (20).…”

Unraveling the Relative Importance of Oral and Dermal Contaminant Exposure in Reptiles: Insights from Studies Using the Western Fence Lizard (Sceloporus occidentalis)

“…Despite recognition that chemical contaminants can and do impact reptiles, the taxon remains understudied in ecotoxicology [2], [3] despite several calls for more research [4], [5]. One of the consequences of a lack of ecotoxicity and exposure data is that ecological risk assessments (ERA) on a reptilian species will have considerable uncertainty reducing the utility of assessment results for sound management decision-making.…”