Given the lack of knowledge about the distribution of species and communities in high-altitude ponds, it is urgent to characterize the effects of climate change on these species and to understand how communities are structured, in order to define research priorities and conservation actions that need to be urgently implemented.

Human activities, through environmental alterations, have triggered the sixth biodiversity extinction crisis: in addition to habitat destruction, the fastest climate change the Earth has experienced since the end of the last Ice Age 18,000 years ago is currently underway (Vitousek et al., 1997). Wetlands are ecosystems that support the greatest biodiversity (Ferrier & Jenkins, 2009; Maltby & Barker, 2009). In times of major global changes, they allow the survival of specialized species (Maltby & Barker, 2009). High-altitude ponds are "small (1m² to a few hectares) wetlands, with a permanent or temporary surface water extent, shallow, located between the limit of natural forests and permanently snow-covered areas" (Wissinger et al., 2016). Due to their location, they are most affected by climate change. At higher altitudes, they remain the least impacted by anthropogenic pressures. These ponds may allow us to better understand the effects of climate change on biodiversity.

The objective of my PhD is to quantify the biodiversity of high-altitude ponds and understand the factors that determine it, predict its evolution in a climate change context, and guide their management, whether in terms of conservation, restoration, or bio-indication.

The PhD work consists of 3 research axes:
Axis 1: What are the known effects of climate change globally on the aquatic communities of high-altitude ponds?
Axis 2: What are the responses of aquatic communities (odonates, amphibians, macrophytes) to the current variation in hydroperiod, water temperature in high-altitude ponds, and the connectivity between ponds or wetland networks across 73 ponds in the French Northern Alps?
Axis 3: Are species assembled based on environmental variable gradients describing high-altitude ponds? Are there differences between groups and across different geographical areas within the same biogeographical region?

References

• Ferrier, R. C., & Jenkins, A. (2009). Handbook of Catchment Management. John Wiley & Sons.
• Maltby, E., & Barker, T. (2009). The Wetlands Handbook, 2 Volume Set. John Wiley & Sons.
• Vitousek, P. M., Aber, J. D., Howarth, R. W., Likens, G. E., Matson, P. A., Schindler, D. W., Schlesinger, W. H., & Tilman, D. G. (1997). Human Alteration of the Global Nitrogen Cycle : Sources and Consequences. Ecological Applications, 7(3), Article 3. https://doi.org/10.1890/1051-0761(1997)007[0737:HAOTGN]2.0.CO;2
• Wissinger, S. A., Oertli, B., & Rosset, V. (2016). Invertebrate Communities of Alpine Ponds. In D. Batzer & D. Boix (Éds.), Invertebrates in Freshwater Wetlands (p. 55‑103). Springer International Publishing. https://doi.org/10.1007/978-3-319-24978-0_3