Environmental radioactivity impacts bioenergetic in tree frog of Fukushima

The Fukushima Daiichi Nuclear Power Plant accident in 2011 resulted in the contamination in radionuclides of the surrounding environment and led to a chronic exposure of local wildlife to ionizing radiation for over a decade. This study investigates the long-term effects of radiocontamination on the tree frogs (Dryophytes leopardus) in Fukushima Prefecture, focusing on bioenergetics, a major process that governs survival and reproduction. Males tree frogs were collected along a gradient of radiocontamination during the breeding season and their energy metabolism was examined, particularly in trunk muscles, heavily involved in calling, and liver, a key organ for detoxification. Our results show that aerobic metabolism in trunk muscles increases with ionizing radiation dose rate, associated with an increase in mitochondrial oxidative capacity. In contrast, liver tissues exhibit a decrease in aerobic metabolism, compensated by an upregulation of anaerobic processes, likely due to tricarboxylic acid cycle impairment. Additionally, we observed an increase in both the hepatosomatic index and overall body condition with rising ionizing radiation levels, indicating physiological changes. These findings suggest that more than ten years after the initial radiocontamination, metabolic processes and physical condition of tree frogs in Fukushima are still modulated in radiocontaminated areas. This highlights the need for further investigations into the ecological and evolutionary consequences of long-term ionizing radiation exposure in affected wildlife populations.