This project assesses the impact of dams on aquatic animal and plant communities in relation to water quality (zooplankton, macroinvertebrates, phytoplankton, periphyton, macrophytes).

The aim of this project is to understand the exchanges between the groundwater and the water in the Sélune river. This knowledge will help prevent the physical, chemical, and biological changes that restoring continuity will cause to the water quality of the Sélune.

This project establishes a baseline, including dams, for trophic interactions between aquatic biocoenoses present on the Sélune, ranging from microorganisms to fish, in tributaries and the river itself from its source to its entry into the estuary.

This project defines the initial state prior to the removal of dams with regard to diadromous fish and invasive crayfish. This will enable the (re)colonization of these species throughout the watershed to be monitored after removal.

This project assesses the impact of restoring connectivity between fish populations following the removal of dams on the Sélune River. It is based on the calculation of a genetic fragmentation index for five fish species.

This project aims to develop and apply a non-invasive method for monitoring migratory fish flows in the Sélune River. The development of this method is based on the analysis of images and videos taken by a hydroacoustic camera positioned in the watercourse.

The hydrographic sections, which make up the waterways, were extracted from the Topage database covering the study area.

Microbial communities play a major role in the functioning of ecosystems: they are at the base of the food chain (primary production) and participate in the degradation of organic matter. These communities are also known to respond rapidly to environmental changes. Like macro-invertebrates, they can be used as ecological indicators. Benthic diatoms are the main photosynthetic organisms in this biological community. The relative abundance of the different species is used to calculate an environmental quality index (EQI). Major differences in communities between the upstream and downstream zones were observed when the dams were in place. These differences will change once the dams are removed. As part of the Sélune observatory, pilot stations have been set up along the main course of the Sélune, distributed from upstream to downstream of the hydroelectric dams. Three stations are located in the former reservoirs of the dams, while the other two, known as the reference stations, are outside the area of influence of the former dams (one downstream and the other upstream). At these stations, aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. Since September 2014, the stations are ideally sampled every month from April to October (7 annual surveys) using artificial substrates (glass slides placed in the water). In addition to the diatom survey (floristic list, IBD calculation), the chlorophyll-a concentration is measured. During each campaign, an INRAe experimental sampling protocol is implemented. This protocol involves the immersion (1 month) of glass slides, an in situ measurement of the chlorophyll-a concentration via BentoTorch and then the collection of the biofilm on these glass slides. The biofilm is conditioned in (1) 99.9% ethanol to determine IBDs and floristic lists (outsourced service, based on standard NF T90-354) and (2) mineral water to measure chlorophyll-a concentration using a spectrometer. NB: the year 2023 is not covered in terms of measuring chlorophyll-a concentration via spectrometry due to a problem with the low-temperature storage of samples. This dataset provides measurements of the average daily concentration of chlorophyll-a and pheopigment in µg/cm2/day.