This study evaluates the utility of the tail of the lizard Microlophus atacamensis as a biomonitor for assessing variation in heavy metals contamination (lead, copper, nickel, zinc and cadmium) using non- or minimally invasive methods that do not require sacrificing animals. Sampling was conducted at three coastal sites in Antofagasta (Atacama Desert) that differ in the degree of human impact. Three matrices were analyzed: soil, lizard tails (biological tissue) and the lizard putative prey. Lizard trophic ecology was characterized using stomach contents and the longer-term stable isotope ratios (δ13 C, δ15 N). We estimated biomagnification and the trophic transfer factor for Pb, Cu, Ni, Zn and Cd. Metal concentrations were analyzed using a generalized linear model (GLMs; Gamma distribution with log link) to assess the effects of matrix (prey, soil, and tails) and site (ISM: Isla Santa María; LCH: La Chimba; COL: Coloso). Full models including interaction effects were significant for metals with the exception of Cu where only the principal matrix effect was significant (prey concentrations effect was significantly greater than both tail and soil). Soil metal concentrations did not differ between sites. Prey items showed substantial variation in metal concentrations that at least between two of the three sites. M. atacamensis tails exhibited elevated heavy metal concentrations that varied significantly among sampling locations. Stomach contents and stable isotope values indicated marked differences in trophic ecology among sites. Overall, the results show that metal burdens in M. atacamensis are influenced by diet and geographic location. We propose that lizard tails represent a useful indicator of heavy metal levels in industrially impacted areas, provided that individuals feed primarily on prey from their immediate habitat, as supported by isotopic evidence.
Marambio-Alfaro et al. (Sat,) studied this question.