Exploring the impact of a perfluoroalkyl substance (PFAS) and interspecific variation in passerine metabolism

Abstract

A comprehensive understanding of physiology is essential for improving risk assessment and management as organisms face compounding stressors, such as environmental contaminants and climate change. Passerines are a diverse and abundant group of birds that are sometimes vulnerable to environmental stressors, making it important to study their physiological responses in greater detail. I approached this challenge by using field flow-through respirometry, a novel method in this context, to investigate the effects of a perfluoroalkyl substance (PFAS), perfluorooctane sulfonate (PFOS), on the metabolic regulation and thyroid function of Tree Swallows (Tachycineta bicolor). Additionally, interspecific differences were examined in metabolic rates and liver weights among three passerine species in northern Minnesota: Tree Swallows, Northern House Wrens (Troglodytes aedon), and Black-capped Chickadees (Poecile atricapillus). It was found that PFOS exposure impacts thyroid hormone concentrations in Tree Swallows but does not significantly impact metabolic rate or growth. Furthermore, interspecific differences in metabolic rates and liver weights were significant, and liver weight may be better at explaining differences in metabolic rate than whole animal mass alone. This integrative study contributes to both an understanding of ecotoxicological impacts of PFAS and a foundation for future comparative physiology studies in passerines.