Evidence of Subclinical Inflammation Relates to PAH Exposure in Overwintering Common Loons (Gavia immer)

Abstract

Common Loons (Gavia immer) are migratory, piscivorous waterbirds that exhibit high wintering site fidelity. Forty-three immature loons were captured in 2013, 2015–2017, in southwest coastal Louisiana, an area moderately to heavily exposed to oil from the Deepwater Horizon oil spill of 2010. We analyzed blood from loons to examine associations between exposure to polycyclic aromatic hydrocarbons (PAH) and 25 blood analytes. Overall, 60% (26/43) of the loons had detectable concentrations of PAHs, with an average concentration of 55.3 ± 10.3 ng/g. After controlling for body weight, loons with detectable blood PAHs had higher concentrations of absolute eosinophils, lymphocytes, or monocytes compared to loons without PAH exposure. This study provides evidence of subclinical inflammation in Common Loons wintering in coastal Louisiana and identifies exposure to PAHs as a stressor, raising concern for potential impaired fitness in this population resulting from low-level exposure to PAHs.