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. At each of these stations, benthic macroinvertebrates (bmi) have been sampled regularly, in spring and autumn, since September 2014 and in accordance with standard NF T 90-333. The fauna inventories obtained after determination can thus be used to calculate biotic indices such as the IBG-DCE and the I2M2. In addition, samples were taken using artificial substrates immersed for 1 month, in order to focus on measuring the ‘dam effect’. The protocol is described in: Piscart C., Moreteau, J.C., Beisel J.N. (2006). Monitoring changes in freshwater macroinvertebrate communities along a salinity gradient using artificial substrates. Environmental Monitoring and Assessment 116: 529-542. This layer gives the results obtained for the IBG-DCE and I2M2 biotic indices with the associated parameters (diversity, variety, etc.), as well as the number of samples taken (‘effort’ column). Finally, the layer contains the output from the ‘ODInvertebres’ diagnostic tool for benthic invertebrates, which aims to identify the most likely anthropogenic pressures causing changes in ecological quality (6 probability values for physico-chemical water quality and 6 others relating to hydromorphology or land use in the catchment area). Reference on ‘ODInvertebres’ : Mondy, C. P., & Usseglio-Polatera P. Using conditional tree forests and life history traits to assess specific risks of stream degradation under multiple pressure scenario. Science of the Total Environment 461 (2013): 750-760. The genus Baetis cited in the fauna lists refers to the genus ‘Baetis lato sensu’ according to the SANDRE nomenclature (Sandre code: 9794). Taxa presenting all of the clearly visible and characteristic morphological criteria enabling them to be accurately identified and in an irreproachable state of conservation are included in the Observatoire Sélune's reference collection. This can be consulted on request (see point of contact).

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. 2 sampling campaigns (spring and autumn) for benthic macroinvertebrates (bmi) have been carried out since September 2014. During each campaign, 2 sampling protocols are implemented: - in accordance with standard NF T90-333, which enables the calculation of the IBG-DCE and I2M2 (‘SURBER’) - via artificial substrates immersed for 1 month (‘SUBART’), in order to focus on measuring the ‘effect of dams’. The protocol is described in: Piscart C., Moreteau, J.C., Beisel J.N. (2006). Monitoring changes in freshwater macroinvertebrate communities along a salinity gradient using artificial substrates. Environmental Monitoring and Assessment 116: 529-542. This layer details the benthic macroinvertebrate taxa and their abundance obtained after analysis (according to standard NF T90-388). These data are distributed by campaign and by sector. Taxa presenting all the morphological criteria clearly visible and characteristic allowing the exactitude of their determination and an irreproachable state of conservation are integrated into the reference collection of the Sélune Observatory. This collection can be consulted on request (see contact point). Taxon determination is based on version v17 of the TAXREF reference. The dataset is currently under embargo.

Stations for continuous measurement of hydrological, physical, chemical and sediment parameters have been installed on the Sélune river, as part of the scientific program to monitor the leveling of the Sélune dams. Measurements have been taken on at least an hourly basis since 2014 at the latest. Since 2019, these stations have been part of the Sélune Observatory, which is responsible for monitoring environmental parameters (biotic and abiotic). All stations measure turbidity, water level and conductivity. Some stations measure additional physico-chemical parameters such as pH, dissolved oxygen and chlorophyll concentration. Samples are also taken at upstream (Pont de Virey) and downstream (Pont de Signy) stations, for laboratory chemical analysis. This layer shows the location of flow measurement stations.

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 various 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. This layer shows the location of the study sectors used to monitor photosynthetic biofilms and the campaigns carried out.

Macrophytes are a group of aquatic plants. They are at the base of the food chain and can provide a habitat for many other species. The relative abundance of different species is used to calculate an environmental quality index (IBMR). 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 reference stations, are outside the area of influence of the former dams (one downstream, the other upstream). At these stations, aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. The parameters monitored are specific composition and cover, at 8 stations in the main course, located upstream, downstream and in neolotic areas of macrophyte communities. The monitoring frequency consists of one annual campaign for stations outside reservoirs (S0, S1 and S5) and two annual campaigns (spring/autumn) for neolotic stations (S2, S3.4, S4.1 and S6). The protocol used is the sampling protocol for macrophytes and bryophytes in accordance with standard NF T90-395 (October 2003), which defines the IBMR. Taxa are sampled for laboratory identification. This layer gives the value of the IBMR and EQR (normalized) index at a station for a campaign, as well as information concerning the robustness of this index, the quantities of taxa used to calculate these indices and also information in terms of the proportion of major floristic groups (heterotrophs, algae, bryophytes, pteridophytes, helophytes, phanerogrames, floating vegetation and submerged vegetation).

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.

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, in situ measurement of chlorophyll-a concentration via BentoTorch and then collection of the biofilm on these glass slides. The biofilm is conditioned in (1) 99.9% ethanol for determination of IBDs and floristic lists (outsourced service, based on standard NF T90-354) and (2) mineral water for measurement of chlorophyll-a concentration using a spectrometer. Taxon identification is based on version v17 of the TAXREF reference. The dataset is currently under embargo.

Macrophytes are a group of aquatic plants. They are at the base of the food chain and can provide a habitat for many other species. The relative abundance of different species is used to calculate an environmental quality index (IBMR). 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 reference stations, are outside the area of influence of the former dams (one downstream, the other upstream). At these stations, aquatic biocenoses (including benthic macroinvertebrates, biofilms, macrophytes, etc.) are monitored. The parameters monitored are specific composition and cover, at 8 stations in the main course, located upstream, downstream and in neolotic areas of macrophyte communities. The monitoring frequency consists of one annual campaign for stations outside reservoirs (S0, S1 and S5) and two annual campaigns (spring/autumn) for neolotic stations (S2, S3.4, S4.1 and S6). The protocol used is the sampling protocol for macrophytes and bryophytes in accordance with standard NF T90-395 (October 2003), which defines the IBMR. Taxa are sampled for laboratory identification. This layer gives Taxon identification is based on version v17 of the TAXREF reference. The dataset is currently under embargo.

The re-establishment of the river continuum on the Sélune after the dams have been levelled will enable colonization of the upper reaches of the basin, which were previously inaccessible to eels. Before the dams were levelled, two main tributaries were used by amphihaline fish for reproduction, in addition to the main river: the Beuvron and the Oir. The eel population of the Sélune was monitored in the pre-flushing phase by abundance index campaigns carried out in 2013, 2015, 2019 on a network of stations covering the entire Sélune hydrographic network. Since 2021, this network of stations has evolved to monitor changes in the part of the watershed accessible following the dismantling of the 2 dams. These data enable us to estimate changes in eel abundance along the Sélune and its tributaries, as well as their size structure before and after the removal of the dams. The inventory is carried out in early September, every other year between 2013 and 2019, then every year since, using an electric fishing device and dip nets. Thirty thirty-second fishing stations are set up. A fishing station comprises approximately 100 meters of river. All eels caught are anaesthetized and biometric measurements are taken (weight, length, horizontal and vertical eye diameter, determination of yellow or silver stage). All eels are released directly at the fishing site. This layer provides station abundances by fishing session.

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 various 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, the stations are 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. This layer gives the IBD and EQR (normalised) index value for a station during a campaign.