High-stress rearing temperature in Acipenser fulvescens affects physiology, behaviour and predation rates

Abstract

Early life stress can lead to long-term behavioural and physiological phenotypic alterations that impact fitness. Understanding effects of environmental stressors on wildlife is important to predict individual and population-level responses to stressors associated with climate change. Lake sturgeon, Acipenser fulvescens, are a regionally threatened fish species that experience high predation rates during larval stages. To investigate effects of a high temperature stressor, we exposed lake sturgeon eggs from four families to 10 °C (low-stress) or 18 °C (high-stress) rearing temperatures. At egg, free embryo and larval stages, we quantified stress levels for individuals from each treatment using whole-body cortisol analysis at baseline and after an acute stressor. At the larval stage, we videorecorded behaviour trials to quantify swimming activity, and we conducted predation trials to quantify survival outcomes for individuals from high-stress and low-stress temperature treatments. Free embryos reared at 18 °C had a significantly smaller cortisol response after exposure to an acute stressor, indicating that chronic high temperature stress may reduce stress reactivity in lake sturgeon. In addition, larvae reared at 18 °C had significantly higher activity levels during behaviour trials and significantly higher survival rates when exposed to crayfish predation, indicating that behavioural alterations induced by early life stress may be adaptive in high-stress contexts such as predation. These findings illustrate the need to experimentally evaluate fitness effects of stressors within ecologically relevant contexts in order to predict population- and community-level outcomes of climate change.