Lead exposure by the brown anole (Anolis sagrei) in New Orleans, Louisiana

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Annelise Blanchette, Jordan Karubian and Alex R. Gunderson, Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, Akhila Gopal, Ecology, Evolution, and Conservation Biology, University of Nevada Reno, Reno, NV, Myra E. Finkelstein, Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA

Background/Question/Methods
Urban areas have quickly becoming a major ecosystem around the world, creating pressure to understand how urbanization effects the evolution and ecology of life. Cities themselves are heterogenous and the novel stressors they create vary across the urban landscape. Lead (Pb) is a highly toxic heavy metal that is pervasive, but patchy, in urban environments because of its historical use in gasoline and paint and continued use in manufacturing. The devastating effects of urban lead on humans have been well documented, but urban wildlife may also be susceptible to sub-lethal lead poisoning because of consistent exposure to contaminated soil, water, and food. Given its toxicity and environmental presence, there is a pressing need to deepen our understanding of lead ingestion at the intersections of wildlife biology and urbanization. This presents a significant gap in our understanding of how environmental toxins may shape ecological and evolutionary processes in human altered landscapes. The purpose of this study was to evaluate lead exposure and begin to examine the effects of lead ingestion in a common urban lizard, the brown anole (Anolis sagrei). We did so in New Orleans, LA, which has well-documented variation in lead contamination across the city. We collected blood samples from adult male brown anoles from neighborhoods with both high and low levels of lead contamination (N=10/neighborhood).
Results/Conclusions
Anoles from the high lead neighborhood had, on average, 16x higher blood-lead levels (mean = 975.14±761.34 ug/dL) than those from the low lead neighborhood (mean = 61.42±86.80 ug/dL, t = -7.60, t-test; p < 0.001). The blood-lead levels observed in the anoles greatly exceed the toxicity thresholds established for other vertebrates. For example, the blood-lead levels of the high-lead anoles were 14x and 54x higher than the toxicity thresholds established for birds (71 ug/dL) and mammals (18 ug/dL), respectively. Additionally, the blood-lead levels of the low-lead anoles were 3x higher than the toxicity threshold for mammals. These results suggest that brown anoles in New Orleans should be experiencing adverse effects of lead contamination and/or have evolved mechanisms to cope with the high lead levels they experience. Future research will explore the developmental, physiological, and cognitive consequences of lead on these animals to help reveal the scope of urbanization impacts on wildlife.