The hidden impact of an invasive predator: Chronic stress in common frog tadpoles

Abstract

The presence of non-native predators can induce chronic stress in native species, but the physiological responses of potential prey are not well understood. We investigated the effects of the presence of a non-native predator, the red-eared slider (Trachemys scripta elegans), on common frog (Rana temporaria) tadpoles. We measured the stress hormone corticosterone (CORT) in tadpoles under two predator treatments: permanent presence and short-term presence before metamorphosis. Tadpoles without predators served as controls. The presence of a slider significantly influenced the CORT levels in tadpoles. A slider's permanent and short-term presence led to lower CORT levels compared to the control group. In addition, tadpoles from the treatment with permanent slider presence metamorphosed smaller and in shorter time.These findings suggest that tadpoles experienced chronic stress in the presence of the predator, resulting in a downregulation of the hypothalamicpituitary–nterrenal axis. Our study highlights the importance of considering the indirect effects of non-native predators on prey species, as chronic stress can have long-term effects on population dynamics and fitness. Understanding stress responses in native species can aid in effective conservation management strategies for non-native predator control.