Jean Guillard

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Verified

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• PhD, HDR
• Research Engeenier - HDR at French National Institute for Agriculture, Food, and Environment (INRAE)

Au cours des dernières décennies, les activités humaines ont entraîné une augmentation de la pollution sonore modifiant les caractéristiques acoustiques des écosystèmes à l'échelle mondiale. Les effets de ces modifications acoustiques suscitent un intérêt croissant sur leurs impacts sur la biocénose et en particulier les poissons. Les effets potent...

Alterations in the acoustic environment owing to anthropogenic sound are recognised as global pollution and strengthening studies in freshwater. This study focuses on the impact of lake seismic surveys on fish. First, we measured individual stress responses, i.e. cortisol levels and oxidative stress, morphological parameters, and stomach contents o...

The response of invasive species to noise and how it can modulate their behavior and ecological impact have received scant attention. We conducted a two-phase laboratory experiment to investigate the effect of motorboat noise on the quagga mussel, Dreissena rostriformis bugensis. We first measured aggregation during a prolonged rearing phase under...

Peri-alpine lakes are vulnerable to climate warming. Water temperature in these lakes has increased and will likely continue in the coming decades, questioning the fate of inhabiting aquatic populations. Understanding how coregonine fishes respond to these changes is of great importance as these are economically and ecologically valuable population...

Inland fisheries play a crucial role in socio-economic activities and food production. However, these fisheries are often less intensively monitored and studied than marine fisheries. In the past two decades, important fluctuations in European whitefish ( Coregonus lavaretus ) landings have been observed in four peri-alpine lakes in France and Swit...

Lakes provide ecosystem services such as water resources, tourism, biodiversity, and fishing, and therefore their management represents important societal challenges. Since the early 1960s, significant anthropogenic pressures (human population growth and industrial and agricultural development) have accelerated the degradation of lake ecosystems, l...

Survival rate of the larval stage is an important driver of fish recruitment. To understand mechanisms regulating larval survival it is important to understand the relative importance of abiotic and biotic factors that shape larval spatial distributions. We studied larval Coregonus distributions in surface waters (surface to 1 m) by repeatedly samp...

Modern challenges in the increasing exploitation of aquatic ecosystems require efficient, reliable, and noninvasive technologies to acquire biomass information on a large scale. For the past 40 years, hydroacoustics has been an essential tool to analyse fish populations and their relationship with the environment. Currently, split-beam echo sounder...

Temperature variation is affecting fish biodiversity worldwide, causing changes in geographic distribution, phenotypic structure, and even species extinction. Incubation is a critical stage for stenothermic species, which are vulnerable to large temperature fluctuations, and its effects on the phenotype at later developmental stages are understudie...

Acoustic cameras are increasingly used for continuous, non-intrusive recording and counting of fish passage in natural environments and artificial structures such as fishways. However, analysing the large number of videos recorded is time consuming. Although automatic reading processes have been developed, the poor quality of acoustic images, inclu...

Salmonids are introduced in various ecosystems, including mountain lakes characterised by extreme environmental constraints. Although these constraints can affect salmonid body condition through direct and indirect pathways, they remain seldom explored despite their importance for understanding salmonid fitness and long‐term establishment. In order...

Tracking the behavior of invasive alien species (IAS) is challenging due to logistical constraints that hinder high frequency surveys. Real-time automated recorders offer a promising solution, but their feasibility needs testing and validation. The acoustic camera is an efficient method to obtain real-time records of the behavior of Hemimysis anoma...

Due to variations in water temperature, climate change impacts the phenology of lake fish population, especially their reproduction. In peri-alpine lakes, whitefish (Coregonus spp.) spawn in very shallow waters in late December and early January when surface water temperature reaches 7 - 8° C. To study spawning phenology, traditional sampling metho...

Species introductions can alter local food‐web structure by changing the vertical or horizontal diversity within communities, largely driven by their body size distributions. Increasing vertical and horizontal diversities is predicted to have opposing effects on stability. However, their interactive effects remain largely overlooked. We investigate...

Synchronic variations in abundance in populations of the same species are common phenomena encountered in various environments, including lakes, and different taxa of freshwater fishes. This phenomenon can be caused by similar environmental conditions across physically separated populations. In the context of the ongoing climate change, it is essen...

Research synthesis on salmonid's introduction in mountain lakes in Savoie (Savoie) led by FSPPMA73 and USMB

Nombre de grands lacs de la planète ne sont, en réalité, pas assez vastes pour faire face aux usages qui en sont faits par les activités humaines, telles qu’elles se déploient depuis plus d’un siècle. Les limites de ces macro-écosystèmes à dimension continentale se manifestent par toute une série de pathologies qui les affectent et qui s’accompagne...

Acoustic cameras are increasingly used in monitoring studies of diadromous fish populations, even though analyzing them is time-consuming. In complex in situ contexts, anguilliform fish may be especially difficult to identify automatically using acoustic camera data because the undulation of their body frequently results in fragmented targets. Our...

Long-term effects of climate change on lakes globally will include a substantial modification in the thermal regime and the oxygen solubility of lakes, resulting in the alteration of ecosystem processes, habitats, and concentrations of critical substances. Recent efforts have led to the development of long-term model projections of climate change e...

The end of the 20th century was characterized by rapid modifications of ecosystem functioning under different pressures (eutrophication, toxic pollution, etc). Rising temperatures in the context of global warming could have indirect consequences, such as increase bioavailability of Hydrophobic Organic Pollutants to aquatic species. These stressors...

L’hydro-acoustique est une méthode non intrusive d’échantillonnage des populations de poissons en écosystèmes lacustres qui permet d’estimer leur abondance et d’étudier leurs relations avec l’écosystème. Elle fait partie des procédures d’échantillonnage potentiellement utilisables pour les programmes de surveillance de la directive cadre sur l’eau...

Biological invasions and anthropogenic noise represent two major threats to fresh water ecosystems but the response of invasive species to noise and how it can modulate their behavior and ecological impact have received scant attention. In this study, we conducted a two-phase laboratory experiment to investigate the effect of motorboat noise on the...

Hemimysis anomala, an invasive alien species (IAS) of the Mysidae family native to the Ponto-Caspian region, has recently established in peri-alpine lakes. In one hand, the proliferation of this IAS is likely to significantly affect lake ecosystems through its competition with planktivorous species. In another hand, this species might have a positi...

The end of the XXth century is characterized by rapidly changing aquatic ecosystems due to the effect of human activities via the increase of multiple stresses. Among these stresses, polychlorinated biphenyls (PCBs) are bioaccumulated by aquatic fauna, and particularly fish, as a result of their lipophilic nature and their low degradation. In addit...

Acoustic cameras are increasingly used in monitoring studies of diadromous fish populations, even though analyzing them is time-consuming. In complex in situ contexts, anguilliform fish may be especially difficult to identify automatically using acoustic camera data because the undulation of their body frequently results in fragmented targets. Our...

We conducted a systematic evaluation of the correspondence in fish length data obtained from vertical hydroacoustics and gillnetting across seven European natural lakes differing in abiotic and biotic characteristics. Length data were analyzed as continuous size spectra characterized by their maximum-likelihood estimated exponents b. First, we exam...

The impacts of invasive species on resident communities are driven by a tangle of ecological interactions difficult to quantify empirically. Combining a niche model with a population dynamic model, both allometrically parametrized, may represent a consistent framework to investigate invasive species impacts on resident communities in a food web con...

The whitefish (Coregonus lavaretus) is a core exploited species in numerous fisheries and the invasion of the European catfish (Silurus glanis) in peri-Alpine lakes may represent an emergent threat to this salmonid. We aimed to assess the whitefish vulnerability to catfish in a French peri-Alpine lake (Lake Bourget) by combining diet analyses (meta...

Climate change modifies the thermal regime and the oxygen solubility of lakes globally, resulting in the alteration of ecosystem processes, lake habitats and concentrations of key parameters. The use of one-dimensional (1D) lake model for global scale studies has become the standard in lake research to evaluate the effects of climate change. Howeve...

Identifying the trophic attributes of co-occurring invaders is a prerequisite to anticipate and mitigate their simultaneous impacts. We used an allometric niche model (aNM) to infer the trophic attributes of a mysid (Hemimysis anomala) and a catfish (Silurus glanis) that recently colonized the largest natural lake in France (Lake Bourget) and we ra...

There is an urgent need to evaluate the effects of anthropogenic pressures and climatic change on fish populations’ dynamics. When monitored in lakes, the spawning of fish is generally assessed using traditional, mostly destructive or damaging, methods as gillnetting and collection of fertilized eggs. Over the last decade, environmental DNA (eDNA)...

High-resolution multibeam sonar allows estimating movements of pelagic fish schools at short range. Taking advantage of this methodology, we calculated a Straightness Index (SI) to quantify the proportion of schools migrating actively from those residents in lagoon channels. This information enhances our knowledge of both fish school displacements...

Used for several decades and recognized today as a reliable method, fishery acoustics is commonly used in scientific studies and monitoring surveys. In Europe, during the last decades, the most frequently used scientific echo-sounder has been the EK60 from the Simrad company (Simrad Kongsberg Maritime AS, Horten, Norway). A new echo-sounder model,...

The European catfish (Silurus glanis) recently colonised large peri‐alpine lakes where its exploitation of the different lake habitats (i.e. littoral, pelagic and deep benthic) may be supported by interindividual trophic variations fostering its establishment. We investigated the prey and lake habitats supporting S. glanis diet in the largest Frenc...

Dans de nombreux écosystème aquatiques, l’abondance des poissons de l’année fluctue fortement. Comme ces individus se nourrissent généralement de zooplancton et sont prédatés par les poissons piscivores, ces fortes fluctuations peuvent avoir un impact fort sur le fonctionnement du réseau trophique ainsi que sur les quantités de poissons capturées p...

La fin du xxe siècle se caractérise par des modifications rapides des écosystèmes aquatiques sous l’effet des activités humaines via l’accroissement de stress multiples. Parmi ces stress, les polluants organiques persistants (POP) sont caractérisés par leurs toxicités reconnues. Parmi ces POP, les polychlorobiphényles (PCB), sont bioaccumulés par l...

Cartoon strips on whitefish spawning phenology and the use of the acoustic camera. A way to explain to the younger generation the impact of climate change on the spawning period of fish in lakes and how to monitor it. To be distributed to school children during the laboratory's open day.

With a growing demand for hydroelectric energy, the number of reservoirs is dramatically increasing worldwide. These new water bodies also present an opportunity for the development of fishing activities. However, these reservoirs are commonly impounded on uncut forests, resulting in many immersed trees. These trees hinder fish assessments by disru...

Starting from a framework defining a fishery as a combination of environmental, biological, social, economic and policy components, we review the development process and current status of the reservoir fishery of Nam Theun 2 Dam in Lao PDR. The aquatic environment was extensively studied and fishing monitored ; the reservoir features a low producti...

The acoustic camera is a non-intrusive method increasingly used to monitor fish populations. Acoustic camera data are video-like, providing information on fish behaviour and morphology helpful to discriminate fish species. However, acoustic cameras used in long-term monitoring studies generate a large amount of data, making one of the technical lim...

A dramatic slowing down of acoustic wave transport in dense fish shoals is observed in open-sea fish cages. By employing a multi-beam ultrasonic antenna, we observe the coherent backscattering phenomenon. We extract key parameters of wave transport such as the transport mean free path and the energy transport velocity of diffusive waves from diffus...

The greatest known global response of lakes to climate change has been an increase in water temperatures. The responses of many lake fishes to warming water temperatures are projected to be inadequate to counter the speed and magnitude of climate change. We experimentally evaluated the responses of embryos from a group of cold, stenothermic fishes...

Environmental sciences depend heavily on observational data. Successful studies of ecological processes in lakes require in‐situ data that cover the relevant temporal scales from milliseconds to entire seasons. Temporal and spatial coverage requirements represent a non‐trivial challenge in lake sciences, which have traditionally used sampling campa...

La fin du XX ème siècle se caractérise par des modification srapides des écosystèmes aquatiques sous l’effet des activités humaines via l’accroissement de stress multiples. Dans ces stress, les polluants organiques persistants (POP) sont caractérisés par leurs toxicités reconnues. Parmi ces POP, les polychlorobiphényles (PCB), sont bioaccumulés par...

Trophic interactions are central in understanding ecosystem processes and the management of natural ecosystems but are frequently complex to estimate. To address this issue, body size has been shown to be a useful trait to reconstruct species interactions, particularly in aquatic ecosystems. An allometric niche model (aNM) considering body size as...

Anthropogenic pressures and more recently climatic change have increased the interest to study the impact of environmental changes on the key stages of fish life cycle. In lake Geneva, a deep peri-alpine lake, climate change and phosphorous level are known to have consequences on salmonid and percid populations, including key species for recreation...

A dramatic slowing down of acoustic wave transport in dense fish shoals is observed in open-sea fish cages. By employing a multi-beam ultrasonic antenna, we observe the coherent backscattering (CBS) phenomenon. We extract key parameters of wave transport such as the transport mean free path and the energy transport velocity of diffusive waves from...

Sediment trapping within reservoirs is a worldwide phenomenon which impairs the ecological functioning of upstream and downstream ecosystems. It also reduces reservoir water storage volume, which lessens the services dams provide such as hydropower production or flood control and questions their sustainability. Hydraulic flushing is a widely used o...

To evaluate the aquatic ecosystem's quality and ensure the sustainable management of fisheries, it is important to monitor fish populations. Hydroacoustics uses sound waves to noninvasively scan and gather information on waterbodies including fish abundance and distribution. Unmanned surface vehicles (USV) have been increasingly used in marine and...

The greatest response of lakes to climate change has been the increase in water temperatures on a global scale. The responses of many lake fishes to warming water temperatures are projected to be inadequate to counter the speed and magnitude of climate change, leaving some species vulnerable to decline and extinction. We experimentally evaluated th...

The combination of global warming and local stressors can have dramatic consequences on freshwater biota. Sediment deposition is an important pressure that can affect benthic species and benthic ontogenetic stages (eggs and larvae) habitat quality. However, knowledge on the effects of sediment in a warming context is lacking. We used a common garde...

For the last two decades, a rapid eutrophication process impacts Lake Titicaca, the largest tropical freshwater lake in South America and the main highest Great Lake. This is especially notorious in the Bolivian sector of its shallow Lago Menor sub-basin. Lago Menor is deteriorated by the combination of multiple contaminations (domestic, industrial...

As the global climate warms, the fate of lacustrine fish is of huge concern, especially given their sensitivity as ectotherms to changes in water temperature. The Arctic charr (Salvelinus alpinus L.) is a salmonid with a Holarctic distribution, with peripheral populations persisting at temperate latitudes, where it is found only in sufficiently col...

Limnothrissa miodon is a small pelagic clupeid that was introduced into Lake Kivu in the late 1950s to fill an empty niche. Since then, it has become the main fishery in the lake. The fish stocks were estimated by hydroacoustics between 2012 and 2018 to provide information on the fishery in the current context of changing environmental factors. The...

Freshwater hydroacoustic surveys are frequently performed with small research boats. Thus, the transducer, usually fixed on a pole on the side of the boat, could be misaligned with the horizontal axis (i.e. the lake surface). Given that fish acoustic responses are strongly directional, the transducer angle could induce attenuation of their backscat...

Multiple scattering of acoustic waves offers a noninvasive method for density estimation of a dense shoal of fish where traditional techniques such as echo-counting or echo-integration fail. Through acoustic experiments with a multi-beam sonar system in open sea cages, multiple scattering of sound in a fish shoal, and, in particular, the coherent b...

Multiple scattering of acoustic waves offers a noninvasive method for density estimation of a dense shoal of fish where traditional techniques such as echo-counting or echo-integration fail. Through acoustic experiments with a multi-beam sonar system in open sea cages, multiple scattering of sound in a fish shoal, and in particular the coherent bac...

Ultrasound scattered by a dense shoal of fish undergoes mesoscopic interference, as is typical of low-temperature electrical transport in metals or light scattering in colloidal suspensions. Through large-scale measurements in open sea, we show a set of striking deviations from classical wave diffusion, making fish shoals good candidates to study m...

In aquatic ecosystems, young of the year (YOY) fish often exhibit strong interannual fluctuations. Because these fish prey on zooplankton and are preyed upon by piscivorous fish, strong fluctuations in their abundance may have important impacts on food web functioning. The static Ecopath model was used to assess potential impacts of strong fluctuat...

Large lakes of the world are habitats for diverse species, including endemic taxa, and are valuable resources that provide humanity with many ecosystem services. They are also sentinels of global and local change, and recent studies in limnology and paleolimnology have demonstrated disturbing evidence of their collective degradation in terms of dep...

The Nile tilapia ( Oreochromis niloticus ) was introduced in Southeast Asia, such as in Thailand, in the mid-1960s for aquaculture purposes (Pullin et al. , 1997; De Silva et al. , 2004). The species was later promoted for aquaculture development in the early 1990s in Lao PDR (Garaway et al. , 2000). In Lao People’s Democratic Republic (PDR), like...

Lakes are essential ecosystems that provide a large number of ecosystem services whose quality is strongly impacted by human pressures. Optimal uses of lakes require adapted management practices which in turn rely on physico-chemical and biological monitoring. Long-term ecological monitoring provides large sets of environmental data. When such data...

Le Carrtel, une UMR d’écologie lacustre face au concept de service écosystémique. Enjeux et interrogations, démarches et prospective

In recent years, due to an increased need for non-intrusive sampling techniques, hydroacoustics has attracted attention in fishery science and management. Efforts to promote standardisation are increasing the accuracy, efficiency, and comparability of this method. The European Water Framework Directive and the Standard Operating Procedures for Fish...

Ultrasound scattered by a dense shoal of fish undergoes mesoscopic interference, as is typical of low-temperature electrical transport in metals or light scattering in colloidal suspensions. Through large-scale measurements in open sea, we show a set of striking deviations from classical wave diffusion making fish shoals good candidates to study me...

The life history traits of Hampala macrolepidota, a common freshwater fish species in Southeast Asia that is of interest for fisheries and sport fishing, were estimated for a population from Nam Theun 2 Reservoir in Lao. The exploitation status of this species was also characterized using data from landing. Toluidine-stained transverse section of o...

Nam Theun 2 is the largest neo-reservoir in Lao PDR that was impounded to produce electricity. The objective of this study was to assess the input of the offshore zone to the total fish production. Hydroacoustics in areas > 5 m deep were sampled during the cold-dry season for 2 consecutive years. Results showed low fish densities (200–300 ind. ha⁻¹...

Total lengths (LT) of 50 free‐swimming fish in a tank, silver carp Hypophthalmichthys molitrix and rainbow trout Oncorhynchus mykiss, were measured using a DIDSON (Dual‐frequency IDentification SONar) camera. Using Sound Metrics software, multiple measurements of each fish (LT, side aspect angle and distance from the camera) at different times were...

Résumé Les peuplements piscicoles introduits représentent une empreinte anthropique majeure de l’histoire biologique des lacs d’altitude. Basé sur un état de l’art, notre travail s’interroge sur la façon dont la production scientifique intègre cette composante ichtyologique introduite. L’étude limnologique de ces milieux se révèle profondément infl...

The avoidance reaction by fish in front of an approaching vessel is a major source of bias in direct biomass assessment and ecological studies based on fisheries acoustics data. An experiment was carried out to compare echosounder data obtained using a small speedboat and a research fisheries vessel generating significant higher noise above convent...

Biological traits of Oreochromis niloticus were studied in order to identify potential differences between the population of the Nam Theun 2 Reservoir and other populations in Asia and in Africa. The study also aimed to characterize the demographic structure of the exploited population by fisheries in the reservoir. Toluidine-stained transverse sec...

Table ronde animée par M. Vidard : « Quelles avancées scientifiques pour répondre aux enjeux sociétaux autour des lacs ? » organisée à la suite du congrès « Big Lakes – Small world » (Evian, septembre 2018). version courte 15 minutes environ : https://www.youtube.com/watch?v=edJ51QFE00U&feature=youtu.be

Hydroacoustics has become a requisite method to assess fish populations and allows to describe the relationships of fish with other elements of the aquatic ecosystem. This nonintrusive method is currently an integral part of the sampling procedures recommended for fish stock assessment by the Water Framework Directive and has been standardized by t...

Biological traits of Oreochromis niloticus were studied in order to identify potential differences between the population of the Nam Theun 2 Reservoir and other populations in Asia and in Africa. The study also aimed to characterize the demographic structure of the exploited population by fisheries in the reservoir. Toluidine-stained transverse sec...

Les peuplements piscicoles introduits représentent une empreinte anthropique majeure de l’histoire biologique des lacs d’altitude. Basé sur un état de l’art, notre travail s’interroge sur la façon dont la production scientifique intègre cette composante ichtyologique introduite. L’étude limnologique de ces milieux se révèle profondément influencée...

The Nam Theun 2 Reservoir, impounded in 2008 on a tributary of the Mekong (Lao PDR), is one of the largest hydroelectric project in Southeast Asia of the last ten years (lake surface between 86 km² at low level and 489 km² at the highest). Many environmental and social programs were developed in collaboration of local institutions and population si...

• Although parasites are expected to affect their host's fitness, quantitative proof for impacts of parasitism on wild populations is hampered by confounding environmental factors, including dietary resource. • Herein, we evaluate whether the physiological conditions of European perch (Perca fluviatilis) in three large peri‐alpine lakes (Geneva, An...