Video multitracking and study of the collective behaviour in tadpoles

Conference (2013, February 21)

Behaviours Associated with Acoustic Communication in Nile Tilapia (Oreochromis niloticus)

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

Radial arm maze as a new paradigm to study collective behaviours in fish

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 ▲]

Video tracking in the extreme: a new possibility for tracking nocturnal underwater transparent animals with fluorescent elastomer tags

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 ▲]

Computerized video multitracking of several small translucent fishes (glass eels) at night with fluorescent elastomer tags

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 ▲]

Etude des mouvements de bancs de poissons: aspects méthodologiques, fonctionnels et comportementaux: revue des techniques de vidéo-tracking appliquées aux poissons

Conference (2010, June 02)

Sound production and associated behaviour in the Nile Tilapia, oerochromis niloticus (Cichlidae)

Conference (2010)

Cumulative effects of road de-icing salt on amphibian behavior

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 ▲]

A video multitracking system for quantification of individual behavior in a large fish shoal: Advantages and limits

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 ▲]

Structure et ontogenèse des comportements de banc chez deux poissons Cichlidés: approche quantitative par l'utilisation du vidéotracking automatisé chez Oreochromis niloticus et Pelvicachromis pulcher.

Doctoral thesis (2008)

Structures and ontogeny of schools in two cichlid fishes: quantitative approach with computerized videotracking systems in Oreochromis niloticus and Pelvicachromis pulcher. by Johann DELCOURT (Behavioural ... [more ▼]

Structures and ontogeny of schools in two cichlid fishes: quantitative approach with computerized videotracking systems in Oreochromis niloticus and Pelvicachromis pulcher. by Johann DELCOURT (Behavioural Biology Unit, Ethology and Animal Psychology, University of Liège, Belgium) The research works presented in this thesis, using new ethometric techniques based on digital imaging analysis, concerns several questions relating to the study of shoaling and schooling behaviours in early stages of life in two Cichlid species. Our two model species, the Nile tilapia (Oreochromis niloticus L.) and Pelvicachromis pulcher, are respectively a mouthbreeder and a substrate breeder. These reproductive and parental strategies have a direct impact on the ontogeny of fry. In this study, we have worked at understanding the impact of these strategies on the ontogeny of shoaling and schooling behaviours. The characterization of these behaviours needed the elaboration of new videotracking systems able to track individually a large number of fish, and the analysis of the spatial and dynamical structure of the group. After an extensive general introduction devoted to the shoaling and schooling behaviours in regards of the ethological study plan, we present our works in three major goals. These three topics concern: 1. Lab works using some classical methods of direct observation and a technique of computerised vision systems (Ethovision®). Moreover, Laboratory studies of fish groups were conducted to develop a new multitracking system, in collaboration with the G.R.A.S.P. (ULg), able to track a large number of unmarked individuals (up to 100 fishes) during several minutes. Thanks these two tracking systems, we studied the fry behaviours at the individual and the groups levels. 2. The emergence conditions of these behaviours. Are the fry able to adopt these behaviours in absence of parents, in absence of external stimuli? In this context, we described the spatial and dynamical (local and global) structures of groups to understand the mechanisms allowing the existence of schools. 3. The ontogeny of shoaling and schooling behaviours in the two model parental species. The first part exposes research devoted to the application, development and validation of the use of two videotracking systems (presented in the material and methods section). The advantages, capacities and limits of these systems are presented. The work concerning the emergence (the mechanisms) and the ontogeny are presented in scientific paper format in the “Results” section. A large general discussion centred on the three major goals (development of new ethometric tools, the structures and mechanisms of schools and the ontogeny of shoaling and schooling behaviours) concludes this PhD dissertation. [less ▲]