Pollutant Exposure Shapes Mitochondrial Bioenergetics in a Wild Seabird

Area of Science:

• Environmental toxicology
• Marine ecology
• Mitochondrial bioenergetics

Background:

• Mercury (Hg) and per- and polyfluoroalkyl substances (PFAS) are known to impair mitochondrial bioenergetics in laboratory settings.
• The effects of these contaminants on mitochondrial function in wild, free-living organisms are largely unknown.
• Scopoli's shearwaters (Calonectris diomedea) are apex marine predators in the Mediterranean Sea, making them suitable subjects for studying contaminant impacts.

Purpose of the Study:

• To investigate the association between foraging habits, contaminant exposure (Hg and PFAS), and mitochondrial bioenergetics in Scopoli's shearwaters.
• To understand how dietary patterns influence pollutant accumulation and subsequent effects on cellular energy production in a wild population.

Main Methods:

• Analysis of mercury and total PFAS concentrations in red blood cells of breeding Scopoli's shearwaters.
• Inference of foraging habits and trophic position using stable isotope analysis.
• Assessment of mitochondrial bioenergetics, specifically proton leakage (LEAK), in relation to contaminant levels.

Main Results:

• Higher mercury concentrations were found in older individuals and males, and were associated with a higher trophic position and coastal foraging.
• Total PFAS concentrations did not show significant associations with age, sex, or foraging habits.
• Increased mercury levels correlated with higher mitochondrial proton leakage, indicating reduced bioenergetic efficiency.
• Specific PFAS showed a negative association with proton leakage, suggesting potential alterations in mitochondrial membrane potential regulation.

Conclusions:

• Foraging ecology significantly influences mercury exposure and its detrimental effects on mitochondrial bioenergetics in this apex marine predator.
• Mercury exposure appears to reduce cellular energy production efficiency, while specific PFAS may affect protective mechanisms against oxidative stress.
• This study underscores the importance of considering foraging behavior when assessing the ecological risks of contaminants to wildlife populations of conservation concern.