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See detailVideo multitracking and study of the collective behaviour in tadpoles
Delcourt, Johann ULg

Conference (2013, February 21)

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See detailBehaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)
Longrie, Nicolas; Poncin, Pascal ULg; Denoël, Mathieu ULg et al

in PLoS ONE (2013), 8(4), 61467

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See detailINVENTAIRE MALACOLOGIQUE DU DOMAINE FORESTIER UNIVERSITAIRE DU SART TILMAN
Léonard, Lilian; Delcourt, Johann ULg; Vilvens, Claude et al

Report (2013)

The Sart Tilman is a vast wooded area of 754 ha located on the south of the city of Liege that hosts the campus of the University of Liege. It is the only large remaining peri-urban forest of this city ... [more ▼]

The Sart Tilman is a vast wooded area of 754 ha located on the south of the city of Liege that hosts the campus of the University of Liege. It is the only large remaining peri-urban forest of this city. The installation of the University in this place was planned in order to discard the threads of real estate business. The absence of major silvicultural treatments for over 50 years has allowed the forest gradually recovering some dynamics of a natural ecosystem although its composition remains largely influenced by past management. Its interest as multi-use area and particularly as a biodiversity reserve is recognized. Nevertheless, internal pressures similar to urbanization spread threaten the integrity of the area. The Scientific Council of the Sites of the Sart Tilman, which is in charge of maintaining the integrity, and promoting the scientific, educational, and aesthetic development of the area, would like to dispose of more biodiversity distribution data to carry on its missions. The present study is an analysis of the malacological diversity of Sart Tilman taking into account the diversity of forest stands. The work began with the design and evaluation of an effective protocol to allow a malacological inventory in the most comprehensive manner as possible. An inventory protocol combining three methods has been applied to the field with a stratified sample strategy taking into account forest type. The inventory reports a list of 43 species and estimates that 5 to 7 additional species are potentially present. The diversity was modelled as a function of environmental descriptors. Models show meaningful effects of drainage, soil pH, and forest type on the richness and species diversity. However, the predictive ability of these models is insufficient to directly predict malacological diversity and to establish scale mapping of the Sart Tilman. Otherwise, malacological diversity is correlated with an index of potential biodiversity resulting from the combination of 10 easily observable indicators like the number of native tree species or the stratification of the stands. [less ▲]

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See detailVideo multitracking of fish behaviour: a review and future perspectives
Delcourt, Johann ULg; Denoël, Mathieu ULg; Ylieff, Marc ULg et al

in Fish & Fisheries (2013), 14(2), 186-204

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns in fish (e.g. schooling behaviour) and to track a very large ... [more ▼]

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns in fish (e.g. schooling behaviour) and to track a very large number of individuals. These new technologies and methods provide valuable information to fundamental and applied science disciplines such as ethology, animal sociology, animal psychology, veterinary sciences, animal welfare sciences, statistical physics, pharmacology, as well as neuro- and ecotoxicology. This paper presents a review of fish video multitracking techniques. It describes the possibilities of tracking individuals and groups at different scales, but also outlines the advantages and limitations of the detection methods. The problem of occlusions, during which errors of individual identifications are very frequent, is underlined. This paper summarises different approaches to improving the quality of individual identification, notably by the development of three-dimensional tracking, image analysis and probabilistic applications. Finally, implications for fish research and future directions are presented. [less ▲]

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See detailIndividual – to – resource landscape interaction strength can explain different collective feeding behaviours
Bode, Nikolai WF; Delcourt, Johann ULg

in PLoS ONE (2013), 8(10), 75879

Taking in sufficient quantities of nutrients is vital for all living beings and in doing so, individuals interact with the local resource environment. Here, we focus explicitly on the interactions between ... [more ▼]

Taking in sufficient quantities of nutrients is vital for all living beings and in doing so, individuals interact with the local resource environment. Here, we focus explicitly on the interactions between feeding individuals and the resource landscape. In particular, we are interested in the emergent movement dynamics resulting from these interactions. We present an individual-based simulation model for the movement of populations in a resource landscape that allows us to vary the strength of the interactions mentioned above. The key assumption and novelty of our model is that individuals can cause the release of additional nutrients, as well as consuming them. Our model produces clear predictions. For example, we expect more tortuous individual movement paths and higher levels of aggregation in populations occupying homogeneous environments where individual movement makes more nutrients available. We also show how observed movement dynamics could change when local nutrient sources are depleted or when the population density increases. Our predictions are testable and qualitatively reproduce the different feeding behaviours observed in filter-feeding ducks, for example. We suggest that considering two-way interactions between feeding individuals and resource landscapes could help to explain fine-scale movement dynamics. [less ▲]

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See detailVideo multitracking to study the fish behaviour
Delcourt, Johann ULg; Ylieff, Marc ULg; Bolliet, Valérie et al

Conference (2012, July 07)

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and ... [more ▼]

With the development of digital imaging techniques over the last decade, there are now new opportunities to study complex behavioural patterns and rhythms in fish (from individual to collective group) and to track a very large number of individuals. These new technologies and methods provide valuable information to fundamental and applied science disciplines such as ethology, animal sociology, animal psychology, veterinary sciences, animal welfare sciences, statistical physics, pharmacology, as well as neuro- and ecotoxicology. Specifically in situations where a large number of individuals are involved, the use of video tracking data is essential, as manual analyses would be complicated, time-consuming and sometimes even impossible. Today, multitracking allows us to observe directly the behaviours of groups, and to determine the real interaction rules by sampling data collected in nature or in the laboratory, without any a posteriori rules as it was and is frequently the case in computer simulation of collective behaviours. With these technologies, the quantitative measures of collective behaviours is now easily accessible, and allow to define social behaviours with more accuracy than just qualitative criteria as is always the case for instance with the definition of shoaling and schooling behaviours. Firstly will be introduced a review of fish video multitracking techniques. This review describes the possibilities of tracking individuals and groups at different scales, but also outlines the advantages and limitations of the different detection methods. The problem of occlusions, during which errors of individual identifications are very frequent, will be discuss. Secondly, our recent contribution in colour-based multitracking will be introduced, notably the new application of fluorescent VIE (Visible Implant Elastomer) tags in automatic tracking technology to study the behaviour of transparent animals like glass eels (Anguilla anguilla) in dim light or in darkness. The method makes it possible to measure the activity (notably distance and speed) of four individuals as a function of tidal and nycthemeral rhythms in the same flume (circular aquarium simulating the river or estuarine conditions) across a wide time scale (from seconds to weeks) in the context of migration in estuary. [less ▲]

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See detailRadial arm maze as a new paradigm to study collective behaviours in fish
Delcourt, Johann ULg; Garnier, Simon; Miller, Noam Y. et al

Poster (2012, July)

Collective decision-making is based on both environmental information perceived by individuals and social interactions with other group members. Determining and analyzing separately both interactions is a ... [more ▼]

Collective decision-making is based on both environmental information perceived by individuals and social interactions with other group members. Determining and analyzing separately both interactions is a real challenge. If the environmental influences on group behaviours can be determined, new possibilities to collect information about processes inside the group become possible. To improve our knowledge of these processes, an experiment where collective decision-making can be measured easily and without any ambiguity is needed. For this perspective, a new paradigm in the study of collective behaviour is introduced here. The radial arm maze is a classical method used to study individual cognitive abilities. Its advantages are firstly to allow control of environmental information; secondly, to realize multi-way tests, and thirdly, to give the opportunity to collect categorical responses like presence/absence. We apply this paradigm for the first time to a whole animal group. We have also developed an image analysis system able to automatically count the number of individuals in every defined zone. Due to this counting, the degree of cohesion, the group stability, the activity and zone preferences can be described as function of factors such as the group size, the defined zones, or the experimental time. The degree of cohesion can be measured by a new index taking into account the number of sub-groups and the size of each ones. Group activity can be measured by the movement of the majority group between arms. This activity allows determining exploratory processes but also whether zone preferences or homing phenomena appear in the absence of any stimulus. To illustrate, our first results from the exploratory behaviour study of shoals of golden shiners (Notemigonus crysoleucas) are introduced. Using this new paradigm, it is now possible to quantify rapidly in a standardised way the collective responses of fish shoals according to the absence or presence of environmental stimuli, and to create experiments where environmental information is controlled. [less ▲]

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See detailShoals and schools: back to the heuristic definitions and quantitative references
Delcourt, Johann ULg; Poncin, Pascal ULg

in Reviews in Fish Biology & Fisheries (2012), 22

The terms 'shoal', 'swarm' and 'school' are very frequently used in research on collective behaviours in animals. Pitcher's definitions are accepted as the authority in the field but are based on a ... [more ▼]

The terms 'shoal', 'swarm' and 'school' are very frequently used in research on collective behaviours in animals. Pitcher's definitions are accepted as the authority in the field but are based on a conceptual criterion of sociability. Without call into question the basis of these definitions, they do not provide tools to determine these behaviours quantitatively. To compare studies between populations, species, taxa or different experimental treatments, and between different authors, quantitative references are necessary. Quantitative measurements of collective behaviours can also test and validate the predictive capacity of computer models by comparing real data from nature so that different models can be compared. The first part of this paper succinctly reviews the definitions and meanings of these behaviours, with particular attention paid to quantitative aspects. This review underlines a series of conceptual confusions concerning these behavioural terms observed in the scientific literature and oral scientific communications. The second part reviews the quantitative parameters developed by biologists studying collective fish behaviours, mainly fish shoals, and by theoretical biologists and physicists studying computer modelling of collective behaviours. The parameters reviewed herein make no attempt to explain the mechanisms and causes that create a shoal, a swarm or a school, but rather try to describe these collective behaviours, and to connect local and global properties with individual and collective behaviours. Recent development over the last decade in technology, data processing capacity, cameras, and video tracking tools have provided the opportunity to obtain quantitative measures of collective dynamic behaviours in animals both rapidly and precisely. [less ▲]

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See detailVideo tracking in the extreme: a new possibility for tracking nocturnal underwater transparent animals with fluorescent elastomer tags
Delcourt, Johann ULg; Ylieff, Marc ULg; Bolliet, Valérie et al

in Behavior Research Methods (2011), 43

Initially developed so that an individual could be recognised in mark-recapture studies of aquatic animals, fluorescent VIE (Visible Implant Elastomer) tags are used here for a new application in ... [more ▼]

Initially developed so that an individual could be recognised in mark-recapture studies of aquatic animals, fluorescent VIE (Visible Implant Elastomer) tags are used here for a new application in ethometry: the study of behavior of transparent animals in dim light or in darkness using automatic tracking technology. The application and validation of this multitracking method is tested in the context of research on the glass eel (Anguilla anguilla) estuarine migratory behavior, a crucial point to better understand the dynamics of this endangered species. The method makes it possible to measure the activity (notably distance and speed) of four individuals as a function of tidal and nycthemeral rhythms in the same flume (circular aquarium simulating the river or estuarine conditions) across a wide time scale (from seconds to weeks). [less ▲]

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See detailNos terrils : leur vraie nature
Delcourt, Johann ULg; Hauteclair, Pascal

Book published by Weyrich Editions (2011)

Yesterday considered as scars from a painful past, nowedays slag heaps are largely adopted in the heart of people. Being an accumutation of steriles in the past, they are become a stock of biodiversity in ... [more ▼]

Yesterday considered as scars from a painful past, nowedays slag heaps are largely adopted in the heart of people. Being an accumutation of steriles in the past, they are become a stock of biodiversity in an affected environment by the Man and global climate changes. However, slag heaps (or spoil tips) own a unknown richness for all a serie of point of view. This book is an invitation to discover the treasures of these mini mountains born from the Man's hands. [this book is written in French] [less ▲]

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See detailComputerized video multitracking of several small translucent fishes (glass eels) at night with fluorescent elastomer tags
Delcourt, Johann ULg; Bolliet, Valérie; Ylieff, Marc ULg et al

Poster (2010, July)

European eels (Anguilla Anguilla), an endangered species with high economic value, exhibit very unusual features in their multistage catadromous life cycle at different life stages. The reproduction of ... [more ▼]

European eels (Anguilla Anguilla), an endangered species with high economic value, exhibit very unusual features in their multistage catadromous life cycle at different life stages. The reproduction of eel takes place in the Sargasso Sea. Leptocephalus larvae use ocean currents (mainly the Gulf Stream) to migrate to European coastal areas, and then metamorphose into glass eels probably as they reach the continental shelf. Glass eel then, enter estuaries to join the fresh waters network. Knowledge about glass eel biology and migration has mainly increased in the eighties, and it is now well established that the activity during the estuary migration depends mainly on tidal cycle, even if lunar and circadian rhythms and/or direct influence of light and tidal coefficient may interact. Different migratory tactics are suspected on the basis of recent laboratory experiments (Bolliet & Labonne, 2008; Bureau du Colombier et al., 2009), notably the existence of individuals swimming only with the current, others swimming with and against the current, and others presenting a weak degree of activity. The propensity to migrate and glass eels energy content would be linked and may result in different migratory behaviours possibly leading to estuarine settlement (Bureau du Colombier et al., 2007; 2009). Unfortunately, few are known about the glass eel swimming behaviours in estuaries, a crucial point to better understand their estuarine migration: such knowledge would help to characterize the migratory tactics and to better understand the link with energy status. The videotracking system [EthoVision Color-Pro 3.1 (Noldus Information Technology)] which allows to measure automatically the movements of individuals represents an interesting tool to progress in this questioning. Nowadays, video tracking to measure fish behaviours is relatively frequent, but is rather rare in the ecological studies. Moreover, tracking a transparent animal, under water current conditions is a real challenge, particularly at night. To detect the individuals, several eels are marked by a fluorescent VIE tag (Visible Implant Elastomer, Northwest Marine Technology Inc.). VIE do no affect growth, survival and behaviour of tagged glass eels. Initially developed to improve the identification of individual tags in mark-recapture studies of aquatic animals, VIE tags are used here for a new extreme application in ethometry: the study of behaviours of transparent animals in weaker luminosity and in the dark by automatic tracking technology. The individual identification is based on the fluorescent color (red, blue, yellow and green) emitted by the VIE tag injected in the muscle mass on the basis of dorsal fin. The detection of the four marks is excellent. It allows measuring the activity (notably path and speed) of each tagged individuals as a function of tidal and nycthemeral rhythms in the same chronotron (circular aquarium simulating the estuarine conditions) and spatial use at a wide time scale from second to week. Another advantage is the possibility of tracked animals to go out the analysed arena without error of identification when it appears again in the analysed zone. This multitracking method by fluorescent VIE tags could be applied to a large number of species (crustaceans, fish, holothurians, amphibians, …). References: Bolliet & Labonne, 2008 Journal of Experimental Marine Biology and Ecology 362, 125-130; Bureau du Colombier et al., 2007 Physiology & Behavior 92, 684-690 ; Bureau du Colombier et al., 2009 Journal of Fish Biology 74, 2002-2013. Acknowledgements: This work was financially supported by FNRS-FRS (National fund of Research, Belgium) (project n°2.4617.08, n°2.4569.06, n°2.4569.10F), by Hubert Curien Tournesol project and by an EGIDE Grant. We thank J-C. Aymes for its help in testing the video tracking software and system. We are also highly grateful to Jacques Rives for its help in settling and monitoring the experiments. [less ▲]

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See detailGlass eel swimming behaviour during their estuarine migration: new insights from video tracking analysis
Delcourt, Johann ULg; bolliet, Valérie; Ylieff, Marc ULg et al

Conference (2010, July)

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See detailEnergie verte = énergie propre? Le cas de l'hydroélectricité
Delcourt, Johann ULg

Article for general public (2010)

Les énergies renouvelables n’émettent pas de gaz à effet de serre ; sont-elles pour autant respectueuses de la biodiversité ? Le cas de l’hydroélectricité, très développée sur nos cours d’eau, soulève ... [more ▼]

Les énergies renouvelables n’émettent pas de gaz à effet de serre ; sont-elles pour autant respectueuses de la biodiversité ? Le cas de l’hydroélectricité, très développée sur nos cours d’eau, soulève sérieusement la question. [less ▲]

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See detailComportements de prédation en faibles profondeurs d'eau chez le Harle bièvre Mergus merganser
Delcourt, Johann ULg

in Aves (2010), 47(4), 201-212

This article describe the predation behaviour of the Common Goosander, observed on the river Ourthe during periods of low water levels. even though it is catalogued as a dinving duck, the bird can ... [more ▼]

This article describe the predation behaviour of the Common Goosander, observed on the river Ourthe during periods of low water levels. even though it is catalogued as a dinving duck, the bird can, starting from the "head under water" posture typical of the species, adopt a mode of search and pursuit of its prey which does not require diving. The "head under water" posture has been noted previously in the specialist literature, but it has never before been so precisely described. The fishing behaviour in very low water levels was never mentioned. We report here observations carried out in September 2009 and June 2010 on the site of the Grosses-Battes in Basse-Ourthe (Angleur, Liège, Belgium). These observations show that some summering individuals prefer a riffle zone as feeding site at times of low water level, even though many depper zones are accessible in the vicinity. [less ▲]

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See detailCumulative effects of road de-icing salt on amphibian behavior
Denoël, Mathieu ULg; Bichot, Marion; Ficetola, G. Francesco et al

in Aquatic Toxicology (2010), 99(2), 275-280

Despite growing evidence of the detrimental effect of chemical substances on organisms, limited research has focused on changes in behavioral patterns, in part due to the difficulties to obtain detailed ... [more ▼]

Despite growing evidence of the detrimental effect of chemical substances on organisms, limited research has focused on changes in behavioral patterns, in part due to the difficulties to obtain detailed quantitative data. Recent developments in efficient computer-based video analyses have allowed testing pesticide effects on model species such as the zebrafish. However, these new techniques have not yet been applied to amphibians and directly to conservation issues, i.e. to assess toxicological risks on threatened species. We used video tracking analyses to test a quantitative effect of an environmental contaminant on the locomotion of amphibian tadpoles (Rana temporaria) by taking into account cumulative effects. Because recent research has demonstrated effects of de-icing salts on survival and community structure, we used sodium chloride in our experimental design (25 replicates, 4 concentrations, 4 times) to test for an effect at the scale of behavior at environmentally relevant concentrations. Analysis of 372 1-hr video-tracks (5 samples per sec) showed a complex action of salts on behavioral patterns with a dose and cumulative response over time. Although no effects were found on mortality or growth, the highest salt concentrations reduced the speed and movement of tadpoles in comparison with control treatments. The reduced locomotor performance could have detrimental consequences in terms of tadpoles’ responses to competition and predation and may be an indicator of the low concentration effect of the contaminant. On one hand, this study demonstrates the usefulness of examining behavior to address conservation issues and understand the complex action of environmental factors and, more particularly, pollutants on organisms. On the other hand, our results highlight the need of new computerized techniques to quantitatively analyze these patterns. [less ▲]

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See detailL'Île aux Corsaires et ses trésors naturels
Delcourt, Johann ULg; Destinay, Philippe; Dirick, Alain et al

Book published by Natagora (Liège et Basse-Meuse) - éditeur responsable: Pierre Tomasovic - natagora Liège et basse meuse (2010)

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See detailA video multitracking system for quantification of individual behavior in a large fish shoal: Advantages and limits
Delcourt, Johann ULg; Becco, Christophe ULg; Vandewalle, Nicolas ULg et al

in Behavior Research Methods (2009), 41(1), 228-235

The capability of a new multitracking system to track a large number of unmarked fish (up to 100) is evaluated. This system extrapolates a trajectory from each individual and analyzes recorded sequences ... [more ▼]

The capability of a new multitracking system to track a large number of unmarked fish (up to 100) is evaluated. This system extrapolates a trajectory from each individual and analyzes recorded sequences that are several minutes long. This system is very efficient in statistical individual tracking, where the individual’s identity is important for a short period of time in comparison with the duration of the track. Individual identification is typically greater than 99%. Identification is largely efficient (more than 99%) when the fish images do not cross the image of a neighbor fish. When the images of two fish merge (occlusion), we consider that the spot on the screen has a double identity. Consequently, there are no identification errors during occlusions, even though the measurement of the positions of each individual is imprecise. When the images of these two merged fish separate (separation), individual identification errors are more frequent, but their effect is very low in statistical individual tracking. On the other hand, in complete individual tracking, where individual fish identity is important for the entire trajectory, each identification error invalidates the results. In such cases, the experimenter must observe whether the program assigns the correct identification, and, when an error is made, must edit the results. This work is not too costly in time because it is limited to the separation events, accounting for fewer than 0.1% of individual identifications. Consequently, in both statistical and rigorous individual tracking, this system allows the experimenter to gain time by measuring the individual position automatically. It can also analyze the structural and dynamic properties of an animal group with a very large sample, with precision and sampling that are impossible to obtain with manual measures. [less ▲]

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