Antoine Stier
Biography
Antoine Stier is affiliated to the French National Centre for Scientific Research (CNRS), working as researcher at the Hubert Curien Pluridisciplinary Institute (IPHC) in Strasbourg (France) and adjunct professor at the University of Turku (Finland). His research is at the intersection between physiology and ecology; it explores the connections between physiological mechanisms and environmental conditions, and how such interactions shape an organism’s phenotype, performance, reproduction and survival.
His work combines field studies and experimental approaches to better understand how organisms respond to rapidly changing environments. He is currently the leader of a long-term project of the French Polar Institute dedicated to studying the physiology and ecology of king penguins, which was initiated in the 1970s (IPEV #119).
Antoine Stier obtained his PhD from the University of Strasbourg in 2013, and then worked as a research fellow at the University of Glasgow (2014-2017), the University of Turku (2018-2021) and Lyon 1 University (2021-2023). He obtained his Docent in physiological ecology from the University of Turku in 2021. He has led three scientific expeditions in the French Southern and Antarctic Lands to conduct fieldwork on king penguins in the Crozet archipelago. He now supervises the teams working on-site every year. He acted as an associate editor for the Journal of Thermal Biology (2021-2024) and is now an associate editor for Functional Ecology. One of his main motivations is the desire to support the development of early-career scientists; he is currently supervising or co-supervising seven PhD students and one postdoctoral researcher.
Fellowship 2026
Dates - 01/09/2026-30/09/2028
Project summary
THIRSTY AND DEHYDRATED AS A KING PENGUIN? MEASURING WATER BALANCE IN THE WILD USING OXYGEN ISOTOPES
Understanding how climate change affects animals is essential to predict ecosystem responses and guide effective conservation strategies. Although polar regions are warming three times faster than the global average, the impact of on-land warming on polar animals remains understudied. Previous research shows that king penguin often exhibit signs of heat stress while breeding on land. They use panting behaviour to cool down, an evaporative cooling mechanism that can lead to significant water loss.
King penguins cannot drink while breeding on land, and thus reproduce in what can be described as a ‘hydric desert’. Consequently, they have to rely on water produced by aerobic metabolism, which may be insufficient to maintain hydric balance in this era of global warming. If penguins suffer from significant dehydration during the breeding period, this could jeopardize their reproductive success and, ultimately, the viability of the species.
Water budgets are difficult to assess in wild animals. The aim of the project is to assess dehydration in king penguins via plasma osmolality, and to use a novel method based on oxygen isotopes (simultaneous measurements of δ17O and δ18O) to assess water inputs and outputs in the animals. To evaluate the strategies that the king penguin may use to limit body water loss, we will concomitantly measure body temperature and energy metabolism, to test the hypothesis that both hypometabolism and facultative hyperthermia may be used to conserve water during periods of hot weather.
By combining historical data (2010-2026) on king penguin reproduction and measures of dehydration from associated archived blood samples, we will be able to test the influence of hot weather conditions on reproductive success, as well as the relative contribution of body water imbalance to reproductive failure. This project will thus help to identify climatic thresholds beyond which breeding success declines, thereby establishing a predictive framework for conservation planning.
