2024 – Mathieu Hélias

I am a PhD student (currently in my second year) at the University of Caen Normandy, based at Cnam-Intechmer in Cherbourg-en-Cotentin. I am particularly interested in the diversity of algae and the communities they form on the foreshore. My thesis work focuses mainly on intertidal macroalgae communities in Normandy.

The aim of my thesis is to develop new tools for understanding these intertidal macroalgae communities at various scales. To this end, a range of techniques are used, from drones for acquiring aerial images of the site to PAM for acquiring data at the individual level. Ultimately, this project aims to improve our understanding of the ecology of Normandy’s foreshores, which will enable us to better understand their future in a context of ever-increasing global change

In the context of this thesis, intertidal macroalgae communities at 12 sites were monitored seasonally to study their structure and dynamics over time. At the same time, measurements of the zoning of various algal species were taken at more than 30 sites in order to understand the vertical structure of Normandy’s foreshores on a large scale. These measurements are made using a new index, THN (Tidal Height Normalization), which allows large-scale comparison of different types of foreshores subject to varying tidal ranges. These data, combined with remote sensing and modeling approaches, enable accurate mapping of Norman macroalgal habitats.

I would like to sincerely thank the French Phycological Society for awarding me a grant, which enabled me to participate in the 25th International Seaweed Symposium (ISS) in Victoria, Canada, in May 2025. This allowed me to present the progress of my research, but also to carry out field surveys in order to test the methods developed in my thesis