Blanche Saint Béat (Takuvik, Québec) seminar

Blanche Saint Béat, a researcher at Takuvik, a joint CNRS/Université Laval international laboratory in Quebec that studies Arctic ecosystems, will present her work on Monday, June 24 at 11 am at IUEM in room A215.

Ecosystems passed to the revelator of network analysis.

Plankton, which is at the base of the pelagic food web, has an essential role in 1) the carbon cycle through biological, lipid and microbial pumps, and 2) as a buffer for environmental variability, necessary to maintain fish resources. In the context of climate change and increasingly high societal challenges, a detailed understanding of the processes structuring food webs and governing their functioning is essential. Over the past few decades, ecological network analysis (ENA) and associated indices have been developed to address these new issues. Indeed, these indices objectively qualify and quantify the emerging properties (not visible in situ) of the ecosystem. These properties, resulting from interactions between species, determine the distribution of carbon through the different flows of the network and characterize the functioning of ecosystems. The ENA indices thus make it possible to discriminate between the functioning of different ecosystems and/or different states within the same ecosystem. The performance of network analysis has made it a very popular tool in ecosystem management and monitoring. However, the robustness of these indices depends on the quality of the carbon flow estimation. Despite the increasing number and performance of instruments deployed in the field, it is almost impossible to measure all in situ flows. Modelling, and more particularly inverse linear modelling, is used to estimate the values of these flows. The performance of these models must be analyzed, verified and improved if necessary. In such studies, the ENA indices are relevant as a validation tool. By providing a global vision of ecosystems, they make it possible to validate ecosystem properties simulated by the models. Thus, whether through ecological or methodological applications, ENA indices are very useful. Examples from my thesis and post-doctoral work will illustrate and discuss the interest of this method and its wide range of applications, both in terms of the issues addressed (stability pattern, sensitivity to integrated information, discrimination of ecosystems, etc.) and the ecosystems studied (intertidal, pelagic, lacustrine, etc.).

Page de Blanche Saint Béat:

Takuvik Laboratory website: