Trace element biodistribution in the American alligator (Alligator mississippiensis)

Routine monitoring of contaminant levels in wildlife is important for understanding chemical exposure and ultimately the link to ecosystem and human health. This is particularly important when the monitored species is recreationally hunted for human consumption. In the southeastern United States, recreational alligator harvesting takes place annually and in locations that are known to be contaminated with environmental pollutants. In this study, we investigated the biodistribution of trace elements in the American alligator (Alligator mississippiensis) from five sites in Florida, USA. These sites are locations where annual recreational alligator harvesting is permitted and two of the sites are identified as having high mercury contamination with human consumption advisories in effect. We utilized routinely collected monitoring samples (blood and scute), a commonly consumed tissue (muscle), and a classically analyzed tissue for environmental contaminants (liver) to demonstrate how the trace elements were distributed within the American alligator. We describe elemental tissue compartmentalization in an apex predator and investigate if noninvasive samples (blood and scute) can be used to estimate muscle tissue concentrations for a subset of elements measured. We found significant correlations for Hg, Rb, Se, Zn and Pb between noninvasive samples and consumed tissue and also found that Hg was the only trace metal of concern for this population of alligators. This study fills a gap in trace elemental analysis for reptilian apex predators in contaminated environments. Additionally, comprehensive elemental analysis of routinely collected samples can inform biomonitoring efforts and consumption advisories.