Thesis Defense // Lina Fabre

THESIS

Factors determining the structure of microbial communities in karst aquatic ecosystems. Prospects for assessing the health of these environments.

Abstract

In some regions, drinking water comes mainly from groundwater that flows through limestone rocks called ‘karsts’. These environments are particularly vulnerable, as pollutants that seep into them can quickly alter water quality and cause supply problems. In this context, this thesis seeks to develop new biological indicators based on microbial communities. The aim is to better detect pollution, but also to assess its persistence over time in order to improve water resource management. To this end, tools (artificial media) have been designed to support the growth of microorganisms. The study revealed that this growth varies according to the ecological state of the environment and that it is possible to identify certain bacteria associated with specific contaminants.
The automated infiltrometer has many advantages over the conventional method in terms of accuracy, reproducibility and ease of use. However, the manual method remains relevant in contexts where resources are limited. Furthermore, the size of the infiltrometer is a determining factor: a larger radius promotes the activation of macropore networks and thus allows for better consideration of preferential flows. Finally, deployment at numerous sites has validated the approach, with satisfactory results in the majority of cases. This study also highlights the need to continue developing alternative algorithms to better represent specific flows, particularly in the case of hydrophobic soils..

Thesis Directors

Florian MERMILLOD-BLONDIN (LEHNA)