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Introduction
Publications
Publications (70)
Understanding ecosystem responses to global change have long challenged scientists due to notoriously complex properties arising from the interplay between biological and environmental factors. We propose the concept of ecosystem synchrony – that is, similarity in the temporal fluctuations of an ecosystem function between multiple ecosystems – to o...
Mars, with its physicochemical conditions resembling Earth's environment 4.5 to 3.5 Ga ago, is a planet of interest in the search for past conditions adequate to life (Cabrol, 2018; Mangold et al., 2021). Sedimentary rocks, specifically their geomorphological properties, have been identified as a promising avenue for detecting bacterial activity in...
Terrestrial subsidies are important for freshwater ecosystems and, in lakes supporting recreational fisheries, angling baits can represent an important allochthonous input. This resource can directly contribute to fish diet but its consumption may be influenced by fish body size and the type of angling baits used in different fisheries. In this stu...
Effective (Ne) and census (Nc) population sizes are key eco-evolutionary parameters. Jointly estimating them have an important practical value for efficient conservation and wildlife monitoring and management. Assessing Ne and Nc remains however challenging for elusive, rare species or species inhabiting in complex habitats like large rivers. Genet...
In streams, phototrophic biofilms are considered to be a good‐quality resource for consumers and are essential to support secondary production. However, with the increasing occurrence of flow intermittency as a consequence of global climate change, limited information exists regarding the impact of drying and rewetting events on biofilm nutritional...
The need to mitigate the effects of climate change is accelerating the development of novel technologies such as floating photovoltaics (FPV). Despite FPV being identified as an emerging issue of concern for biodiversity conservation, it is fast spreading globally and our understanding of their potential ecological impacts is limited. We present an...
Habitat coupling, where consumers acquire resources from different habitats, plays an important role in ecosystem functioning. In this study, we provide a global investigation of lake habitat coupling by freshwater fishes between littoral (nearshore) and pelagic (open water) zones and elucidate the extent to which magnitude of coupling varies accor...
Biological invasions are a major component of global change worldwide. But paradoxically, an invasive species might also have threatened populations within its native range. Designing efficient management policies is needed to prevent and mitigate range expansions of invasive alien species (IAS) in non-native areas, while protecting them within the...
The increase in heatwave intensity and duration is challenging microalgal photosynthesis in shallow waters. In particular, the extent of photosynthesis impairment or limitation due to short extreme heat stress events occurring during a heatwave remains unknown.
In this study, we investigated the importance of microalgal diversity and thermal histor...
In intermittent rivers, which represent a prominent part of worldwide rivers, aquatic organisms are exposed to sequential disturbances including flow cessation, potentially associated with water warming, desiccation process and flow resumption. At flow resumption, pollutants stored in soil and washed by rainfalls can reach fresh waters. The interac...
Hypoxic events have always naturally occurred in freshwater ecosystems but are worsening due to anthropogenic activities. Hypoxia tolerance greatly varies among fish species and is difficult to quantify in nature in large fish species. We analysed the movements of 40 subadult and adult European catfish Silurus glanis [(727; 2150) mm] exposed to a n...
Recreational fishing, through groundbaiting, provides a potentially important trophic subsidy to freshwater ecosystems that could promote eutrophication. To date, our understanding of the role of bait properties on their fate when they are not consumed remains limited. The present study aimed to determine if the C:N:P composition of some of the mos...
High environmental microplastic pollution, and its largely unquantified impacts on organisms, are driving studies to assess their potential entry pathways into freshwaters. Recreational angling, where many anglers release manufactured baits into freshwater ecosystems, is a widespread activity with important socio-economic implications in Europe. It...
European catfish Silurus glanis is a large non-native opportunistic predator able to develop hunting strategy in response to newly available prey where it has been introduced. Migrating spawning anadromous prey such as allis shad Alosa alosa could represent this available and energy-rich food resource. Here, we report an impressive catfish hunting...
Aquatic ecosystems are exposed to multiple stressors such as agricultural run-off (ARO) and climate-change related increase of temperature. We aimed to determine how ARO and the frequency of its input can affect shallow lake ecosystems through direct and indirect effects on primary producers and primary consumers, and whether warming can mitigate o...
The effects of climate change on aquatic biofilm structure and function is difficult to predict mainly due to biofilms being complex and dynamic assemblages of microorganisms. We review observed patterns of the effects of warming and desiccation on biofilms. Commonly observed effects of warming on biofilms include changes in the autotrophic communi...
Sea lamprey (Petromyzon marinus) is a unique jawless vertebrate among the most primitive of all living vertebrates. This migratory fish is endangered in much of its native area due to dams, overfishing, pollution, and habitat loss. An introduced predator, the European catfish (Silurus glanis), is now widespread in Western and Southern European fres...
Intraspecific trait variability (ITV) maintains functional diversity in populations and communities, and plays a crucial role in ecological and evolutionary processes such as trophic cascades or speciation. Furthermore, functional variation within a species and its populations can help buffer against harmful environmental changes. Trait variability...
Teleost fishes interact with diverse microbial communities, playing crucial functions for host fitness. While gut microbiome has been extensively studied, skin microbiome has been overlooked. Specifically, there is no assessment of the relative impact of host and environmental factors on microbiome variability as well as neutral processes shaping f...
Water quality is strongly related to a river's ecosystem composition at landscape scale. Key water/sediment interfaces, referred to here as functional compartments (FCs), are the epilithic biofilm, the fine sediment at the bottom of the river and the macroporous medium or hyporheic zone, which is primarily located in the active channel where subsur...
Elasticity is a trait of biofilm physiognomy which relates to cell clustering and can be measured by means of an electrochemical assay based on rotating disc electrode (RDE). This study aimed at testing the hypothesis according to which exposure of phototrophic biofilm to toxicant could reduce its elasticity. We compared biofilms developed for 21 d...
The Atlantic salmon (Salmo salar) is one of the world’s most emblematic freshwater fish. Despite conservation and rehabilitation plans, populations of this species are dramatically declining due to human impacts such as habitat fragmentation, overfishing and water pollution. Owing to their large body size, anadromous adults were historically invuln...
Adult Atlantic salmon have a new freshwater predator.
(MP4)
The extreme body sizes of megafishes associated with their high commercial values and recreational interests have made them highly threatened in their native range worldwide by human-induced impacts such as overexploitation. Meanwhile, some megafishes have been introduced outside of their native range. A notable example is the European catfish (Sil...
Increases in both food availability and intraspecific competition downstream of dams have the potential to trigger the emergence of trophic specialisation among fish predators, with considerable implications for prey species populations. The aim of this study was to assess whether the presence of a dam located on the River Garonne (France) affected...
The non-native rainbow trout (Oncorhynchus mykiss) has been introduced worldwide for angling purposes and has established self-reproducing populations in many parts of the world. Introduced rainbow trout often have negative effects on the native salmonid species, ranging from decrease abundance, growth and survival, to their local extinction. Asses...
In this study, the results of conventional stomach-content analysis are compared with the recent DNA metabarcoding approach on faeces to identify fish species consumed by non-native European catfish Silurus glanis in the Garonne River (south-western France), with a special emphasis on anadromous prey. Fourteen prey species were identified in the st...
The European catfish Silurus glanis is the largest freshwater fish (excluding anadromous species) in Europe. Its measurements raise many concerns about its potential impact on recipient ecosystems and fish communities and also feed many rumors and fantasies. It is largely accepted that the largest individual ever caught was 5 m long and weighed 306...
Niche-based hypotheses have been proposed to explain processes and mechanisms of success in the establishment of non-native species into native communities. Competition due to niche overlap may lead to native species niche shift and to native species replacement. To understand the ecological consequences of trophic interactions between non-native r...
Despite significant progress in recent years, understanding the rules governing the assembly of natural communities is still challenging and knowledge of how the integration of nonnative species may disrupt community structure and function is needed. To address this challenge, we collated stable isotope data for 159 freshwater fish communities arou...
We filmed and analysed, in natural and field conditions, behaviours of large-bodied European catfish (Silurus glanis) individuals (body size ranging from 80 to 220 cm) exposed to a hook baited with 20 cm-long Carassius spp. Among a total of 95 individuals observed, 80 % of the catfish clearly demonstrated interest in the bait but attacks were perfo...
The distribution and function of microorganisms are of crucial importance for the flow of matter in the Earth's biogeochemical cycles. Effects of microbial communities on the carbon and nitrogen cycles are particularly important for producing climate gases such as CO(2), CH(4), or N(2)O. However, the biogeochemical cycles are reversely impacted by...
Dietary plasticity of populations can be associated to ontogenetic diet preferences and
depends on the size-structure of populations. Dietary niche characterizes the functional role of organisms
in a food web, as it reflects both resources’ diversity used by a consumer and trophic interactions in the
system. Dietary niches are controlled both by bi...
Aim
Despite a long‐standing research interest in the association between the biodiversity (i.e. taxonomic and functional composition) and trophic structure of communities, our understanding of the relationship remains limited. Community assembly theory predicts that niche partitioning will result in communities with a diverse array of functional tr...
Multiple anthropogenic pressures including the widespread introductions of non-native species threaten biodiversity and ecosystem functioning notably by modifying the trophic structure of communities. Here, we provided a global evaluation of the impacts of non-native species on the isotopic structure (δ13C and δ15N) of freshwater fish communities....
The European catfish, Silurus glanis , was widely introduced in western Europe, and it has now established self‐sustaining populations in numerous large rivers of western France. Using data collected from surveys conducted by the French National Agency for Water and Aquatic Environment (Onema) from 1989 to 2010 in more than 500 sites throughout the...
Invasive species may have strong negative impacts on ecosystems. Invasive crayfish are well known to cause ecological imbalances in freshwater systems and have become targets in eradication programmes.
The red swamp crayfish ( Procambarus clarkii ) is vulnerable to predation by several fish species. The European eel ( Anguilla anguilla ) appears to...
The behavioral strategies developed by predators to capture and kill their prey are fascinating, notably for predators that forage for prey at, or beyond, the boundaries of their ecosystem. We report here the occurrence of a beaching behavior used by an alien and large-bodied freshwater predatory fish (Silurus glanis) to capture birds on land (i.e....
Stable isotope values of the three potential prey sources (fish, crayfish and pigeon) used in the mixing models. Reported values are the number of sampled individuals (n) and mean (± SD) δ13C and δ15N (in ‰).
(DOC)
Movie showing European catfish displaying beaching behavior to capture land birds, with two successful and two unsuccessful attacks.
(WMV)
This study aims to identify large-scale environmental variables that explain the distribution of continental exotic fish across five bioclimatic regions in east Algeria (160,000 km²), North Africa. Fish communities were sampled at 39 sites from 2007 to 2010. Seven environmental variables were investigated: habitat type, altitude, latitude, longitud...
Habitat stability is an important driver of ecological community composition and development. River epilithic biofilms are particularly unstable habitats for the establishment of benthic communities because they are regularly disturbed by floods. Our aim was to determine the influence of habitat instability on meiobenthic organisms. We hypothesized...
Abstract Freshwater fish ecology has greatly benefited from the use of innovative tools such as stable isotope analysis to determine the ecological effects of non-native fishes. Stable isotope analyses are based on the predictable relationship between the isotope composition of a consumer and its prey, and have become increasingly popular amongst...
Denitrification is an ecosystem service of nitrogen load regulation along the terrestrial-freshwater-marine continuum. The present study documents the short-term temperature sensitivity of denitrification enzyme activity in phototrophic river biofilms as a typical microbial assemblage of this continuum. Denitrification measurements were performed u...
Movie showing the aggregations of Wels catfish (Silurus glanis).
(WMV)
The ubiquity and fascinating nature of animal aggregations are widely recognised. We report here consistent and previously undocumented occurences of aggregations of a giant alien freshwater fish, the Wels catfish (Silurus glanis). Aggregative groups were on average composed of 25 (± 10 SD, ranging from 15 to 44) adults with estimated average total...
Electroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons...
The biomass dynamics of epilithic biofilm, a collective term for a complex microorganism community that grows on gravel bed rivers, was investigated by coupling experimental and numerical approaches focusing on epilithic biofilm‐flow interactions. The experiment was conducted during 65 days in an artificial rough open‐channel flow, where filtered r...
The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing...
Chronic detachment of the 'Epilithic Biofilm' (EB) was investigated by coupling experimental and numerical approaches focusing on EB-flow interactions during 65 days in an artificial rough open-channel flow. Local hydrodynamic conditions were measured by Laser Doppler Anemometry and numerical simulations of the EB biomass dynamics were performed wi...
“Epilithic biofilm (EB)” is a collective term for a complex micro-organism community which grows on stream beds and includes algae, bacteria and microfauna, with algae usually the dominant component. This community plays a major role in fluvial ecosystems because it is an autochthonous source of organic matter, a transient storage zone for nutrient...
A 15-week experiment was performed in a riverside laboratory flume (with diverted river water) to check variations of river biofilm structure (biomass, algal and bacterial compositions) and function (community gross primary production GPP and respiration) under constant flow while water quality went through natural temporal variations. One major su...
Epilithic bacterial community viability was assessed on natural biofilm assemblages from environmentally contrasting locations
over a 17-months period to determine if it reflects environmental conditions or conditions within the biofilm assemblage.
Vital state was assessed by membrane integrity using LIVE/DEAD®
BacLight™ staining kit. Samples were...
Temporal patterns in biomass and in the production of inhibitory compounds were assessed for a diatomdominated epilithic biofilm of a shallow temperate river. Biomass showed a typical seasonal pattern with the development of two peaks of biomass parallel with species successions. Analysis with self-organizing maps (SOM), a non-supervised neural net...
The present study sought to identify a minimal adequate model to describe the biomass dynamics of river epilithon, a functional indicator of river health. Identification of minimal adequate models is particularly necessary in river management, given the reduced number of variables authorities are willing to measure routinely. A model previously dev...
L'identification et la description des processus qui contrôlent la dynamique du biofilm épilithique en milieu naturel ont été réalisées expérimentalement et à l'aide de l'outil numérique. Ce travail s'appuie sur diverses séries temporelles de biomasse épilithique : (i) 11 séries collectées dans 5 stations de l'Agüera (Espagne) pendant 3 années d'éc...
Trophic interactions among micro- and mesozooplankton were investigated in the Schelde estuary. Field populations of plankton
were separated by selective filtrations (30 and 200 μm). Predation was measured by comparing ciliate and rotifer abundance
in treatments with and without potential predators (cladocerans, cyclopids, the calanoid Eurytemora a...
1. Epilithic biofilm biomass was measured for 14 months in two sites, located up- and downstream of the city of Toulouse in the Garonne River (south-west France). Periodical sampling provided a biomass data set to compare with simulations from the model of Uehlinger, Bürher and Reichert (1996: Freshwater Biology, 36, 249–263.), in order to evaluate...
A compilation of available data in between 1967 and 2002 on spring zooplankton abundance was made for the brackish and the freshwater zone of the Schelde estuary. The general picture is a significant increase of 1–2 orders of magnitude in abundance for Rotifera, Copepoda and Branchiopoda (mainly Cladocera) in the freshwater zone, while zooplankton...
In fluvial ecosystems dominated by fixed biomass at the bottom, the epilithic biofilm imust be included in numerical modellings of biogeochemical fluxes. Among the external factors that control the growth of this biofilm, the hydrodynamics is essential since involved in many relevant processes (colonization, nutrients fluxes, sloughing). Retroactiv...
