References of "Bergé, Julien"
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See detailFish responses to artificial flow and water temperature variability in a large river (Rhône, France)
Capra, Hervé; Ovidio, Michaël ULg; Pella, Hervé et al

in Proceedings of the 9th International Conference on Ecohydraulics (2012, September)

Understanding fine scale behavioural responses of fish to changes in abiotic characteristics of habitat, such as flow variability, is an interesting innovative issue to improve river management in highly ... [more ▼]

Understanding fine scale behavioural responses of fish to changes in abiotic characteristics of habitat, such as flow variability, is an interesting innovative issue to improve river management in highly disturbed aquatic environments. For example, in the Rhône River (France), important hydrology and thermal contrasts are mainly explicated by the succession of dams and nuclear power plants. The main aim of our study was to describe fish behaviour in term of movements and habitat use as responses to habitat variability due to the production of peaking electricity and temperature heterogeneity (natural or due to a nuclear power plant release). Fixed telemetry system (accuracy of few square meters; Hydroacoustic Technology Inc.) enabled to define individual fish behavior during different short habitat variability configuration (flow increase, flow decrease, temperature increase....). We then recorded at a local scale continuous movements of n=61 fish during short term (lower than day) habitat variability. The study was conducted in a 2 km long river stretch, from July to September 2009. Abiotic conditions (temperature, depth, velocity or substrate) were simulated (with an accuracy comparable with fish positioning accuracy) every where at any time (i.e. for any discharge) using a hydraulic 2D model calibrated and validated for the whole discharge range observed during the experiment. Three main species were represented : two native cyprinids, chub (Squalius cephalus) and barbel (Barbus barbus), and an invasive species, wels catfish (Silurus glanis). Fish mobility and habitat use were studied to describe changes in behavior associated with changes of abiotic conditions. The separate effects of each environmental factors (discharge, temperature, photoperiod) and their interactions on fish behavioral responses were studied. Finally, variability of fish habitat preferences were estimated to refine understanding of observed behaviors. The different results highlighted the advantages and limitations of the telemetry acoustic system in a large river to address fish displacement in response to discharge and temperature variability. They also emphasized the necessity of a 2D hydrodynamic model to understand fish behaviour. [less ▲]

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See detailModélisation hydrodynamique et télémétrie : vers de nouvelles connaissances pour l'écologie des poissons du Rhône
Capra, Hervé; Ovidio, Michaël ULg; McNeil, Eric et al

in IS Rivers Extended Abstract book (2012, June)

The article presented herein aims to demonstrate how a two-dimensional hydrodynamic model representing abiotic conditions can be used to study the behaviour of fish affected by large fluctuations of ... [more ▼]

The article presented herein aims to demonstrate how a two-dimensional hydrodynamic model representing abiotic conditions can be used to study the behaviour of fish affected by large fluctuations of environmental conditions in the Rhône River. This represents a major advancement in the understanding of aquatic community structures and in particular, for the structure of fish communities that are rarely used in France. For the first time, the environmental conditions affecting fish and their spatial localization will be simultaneously known. The model can also simulate habitat conditions and water temperatures over longer time frame. For example, this methodology is compatible with the monitoring of fish communities of the Rhône River, which was initiated in 1979. The interest in modeling precise habitat and temperature conditions with hydrodynamic models for a large array of flows allows one to consider the role that these two key environmental factors play on fish behaviour. [less ▲]

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See detailProbability of detection and positioning error of a hydro acoustic telemetry system in a fast-flowing river: intrinsic and environmental determinants
Bergé, Julien; Capra, Hervé; Pella, Hervé et al

in Fisheries Research (2012), 125-126

In situ fixed acoustic telemetry methods make it possible to study simultaneously the detailed movements of individual fish and their relationship to the environment, but the properties of these methods ... [more ▼]

In situ fixed acoustic telemetry methods make it possible to study simultaneously the detailed movements of individual fish and their relationship to the environment, but the properties of these methods is little known in harsh physical conditions. We examined the probability of tag detection by the system and the positioning error for detected tags of an existing telemetry system installed with 32 fixed hydrophones in a reach of the fast-flowing Rhône River in France. The reach was 1.8 km long and had heterogeneous thermal and hydraulic conditions described by a two-dimensional hydraulic model. We compared positions detected by the system with true positions estimated using a tachometer or a differential GPS, for various sets of experimental tag emissions. We analyzed how the probability of detection and the positioning error were affected by user-defined variables and three groups of environmental variables describing the configuration of the hydrophones around tag position, the physical environment at tag position and the reception quality. Tag emissions from the center channel had an average probability of detection (40-50%) higher than emissions originating from positions close to the banks, and were positioned with smaller average errors (3-5 m). The probability of detection of emissions typically varied between near 0% and 80% with configuration variables (density of surrounding hydrophones and location of tag relative to the hydrophones) and also decreased in the presence of coarse substrate. The positioning error was mainly reduced when user-defined variables of the triangulation software were set by an expert user. Configuration variables also influenced the positioning error with weaker effects than those observed for detection probability. [less ▲]

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See detailDescription of Fish Mobility and Habitat Use in a Large Regulated Fast Flowing River (the Rhône River, France) Using Fine Scale Acoustic Tracking
Bergé, Julien; Capra, Hervé; Pella, Hervé et al

Conference (2011, September)

Understanding fine scale behavioral responses of fish to changes in abiotic characteristics of streams (in term of flow and water temperature) is an interesting innovative issue to improve river ... [more ▼]

Understanding fine scale behavioral responses of fish to changes in abiotic characteristics of streams (in term of flow and water temperature) is an interesting innovative issue to improve river management of highly disturbed large rivers. Acoustic telemetry system have become an essential technology for such studies involving continuous (per second) and accurate tracking of fish movements. In the Rhône River (France), important hydrology and thermal contrasts are mainly explicated by the succession of dams and nuclear power plant from the Leman Lake (Switzerland). In this context, it is likely that fish are compelled to adapt their behaviour and their habitat selection in this changing environment. In order to test this hypothesis, a fixed acoustic telemetry survey was performed in the Rhône River during summer 2009 in front of the Bugey nuclear power plant which released warmed water within the river. A study site of 1.8 km long and 140 m wide was monitored using 32 hydrophones developed by HTI® (Hydroacoustic Technology Inc.). Sixty two fish mainly belonging to three species barbel (Barbus barbus), chub (Leuciscus cephalus) and wels catfish (Silurus glanis) were marked with acoustic tags (307 KHz; pulse rate ~ 3 sec.) and followed continuously during 89 days. Fish positions were coupled with a 2D hydraulic model to obtain main physical characteristics encountered by fish such as flow velocity, water depth, water temperature and substrate. The accuracy of the telemetry system was checked and a positional error less than 4 m was found in the channel (detection efficiency of 50 %) and less than 8 meters along the banks (detection efficiency of 20 %). Behavioral responses of fish were investigated through the individual mobility and activity during selected phases of flow (increase, decrease and stability) and water temperature changes (imposed by both warm water plumes and the rapid transition of deep cold waters from the Leman Lake discharged within the river). Mobility and activity of fish were particularly studied to determine the amount of movement associated with a change of abiotic conditions. The separate effects of each environmental factors on behavioral responses of fish were studied and interactions between factors were analyzed to highlight potential synergistic or antagonistic effects. Finally, movement rules (i.e. individual movement decisions in a particular surrounding environment) were analyzed to determine the role of perception of the environment by fish (i.e. how the fish feel the changes in physical habitat) in the use of space. [less ▲]

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See detailUse of Fixed and Mobile Acoustic Telemetry Systems to Understand Fish Responses to Habitat Variability in a Large River (Rhône, France)
Capra, Hervé; Pella, Hervé; Ovidio, Michaël ULg et al

Conference (2011, September)

The presentation would summarize the advantages and limitations of both fixed and mobile acoustic telemetry equipment deployed in a fast flowing large river : the Rhône river (France). The objectives were ... [more ▼]

The presentation would summarize the advantages and limitations of both fixed and mobile acoustic telemetry equipment deployed in a fast flowing large river : the Rhône river (France). The objectives were to describe fish behavior in term of fish movements as responses to habitat variability due to the production of peaking electricity and temperature heterogeneity (natural or due to a nuclear power plant release). At a local scale we used a fixed automatic acoustic telemetry system to record continuous movements of n=62 fish during short term (lower than day) habitat variability. The study was conducted in a 2 km long river stretch, from July to September 2009. In a 35 km long study site, we used a mobile acoustic telemetry system to record weekly position of n=108 fish over different seasons and different habitat conditions (low or high flows; low or high temperature...), from March to December 2010. Discharge and abiotic conditions (temperature, depth, velocity or substrate) were known (with an accuracy comparable with fish positioning accuracy) every where at any time (i.e. any discharge) using hydraulic 2D model calibrated and validated for the whole discharge range observed during telemetry studies. Fixed telemetry system (accuracy of few square meters) enabled to define individual habitat use during different short habitat variability configuration (flow increase, flow decrease, temperature increase....). Three main species were represented : two native cyprinids, chub (Leuciscus cephalus) and barbel (Barbus barbus), and an invasive species, wels catfish (Silurus glanis). We analyzed habitat used, habitat preference, fish movement patterns versus habitat variability. Mobile telemetry system (accuracy of few hundred square meters) enabled to evaluate space and time utilisation of fish (mainly the same species than for fixed telemetry study) at a larger scale and during different seasons encompassing the reproduction period, the summer or the winter periods. The different results obtained by both telemetry systems will be presented to illustrate the advantages and limitations of those systems in a large river to address fish displacement in response to discharge and temperature variability. This comparison also emphasized the contribution of a 2D hydrodynamic model to understand fish behaviour. [less ▲]

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