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Henninger J, Krahe R, Sinz F, Benda J. Tracking activity patterns of a multispecies community of gymnotiform weakly electric fish in their neotropical habitat without tagging. J Exp Biol 2020; 223:jeb206342. [PMID: 31937524 DOI: 10.1242/jeb.206342] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 01/06/2020] [Indexed: 01/06/2023]
Abstract
Field studies on freely behaving animals commonly require tagging and often are focused on single species. Weakly electric fish generate a species- and individual-specific electric organ discharge (EOD) and therefore provide a unique opportunity for individual tracking without tagging. Here, we present and test tracking algorithms based on recordings with submerged electrode arrays. Harmonic structures extracted from power spectra provide fish identity. Localization of fish based on weighted averages of their EOD amplitudes is found to be more robust than fitting a dipole model. We apply these techniques to monitor a community of three species, Apteronotus rostratus, Eigenmannia humboldtii and Sternopygus dariensis, in their natural habitat in Darién, Panama. We found consistent upstream movements after sunset followed by downstream movements in the second half of the night. Extrapolations of these movements and estimates of fish density obtained from additional transect data suggest that some fish cover at least several hundreds of meters of the stream per night. Most fish, including E. humboldtii, were traversing the electrode array solitarily. From in situ measurements of the decay of the EOD amplitude with distance of individual animals, we estimated that fish can detect conspecifics at distances of up to 2 m. Our recordings also emphasize the complexity of natural electrosensory scenes resulting from the interactions of the EODs of different species. Electrode arrays thus provide an unprecedented window into the so-far hidden nocturnal activities of multispecies communities of weakly electric fish at an unmatched level of detail.
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Affiliation(s)
- Jörg Henninger
- Institut für Neurobiologie, Eberhard Karls Universität, 72076 Tübingen, Germany
| | - Rüdiger Krahe
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany
- McGill University, Department of Biology, 1205 Ave. Docteur Penfield, Montreal, Quebec, Canada, H3A 1B1
| | - Fabian Sinz
- Bernstein Center for Computational Neuroscience, Eberhard Karls Universität, 72076 Tübingen, Germany
- Institut für Informatik, Eberhard Karls Univzersität, 72076 Tübingen, Germany
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Center for Neuroscience and Artificial Intelligence, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jan Benda
- Institut für Neurobiologie, Eberhard Karls Universität, 72076 Tübingen, Germany
- Bernstein Center for Computational Neuroscience, Eberhard Karls Universität, 72076 Tübingen, Germany
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Guariento RT, Mosqueiro TS, Matias P, Cesarino VB, Almeida LOB, Slaets JFW, Maia LP, Pinto RD. Automated pulse discrimination of two freely-swimming weakly electric fish and analysis of their electrical behavior during dominance contest. ACTA ACUST UNITED AC 2017; 110:216-223. [PMID: 28188835 DOI: 10.1016/j.jphysparis.2017.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 01/24/2017] [Accepted: 02/05/2017] [Indexed: 10/20/2022]
Abstract
Electric fishes modulate their electric organ discharges with a remarkable variability. Some patterns can be easily identified, such as pulse rate changes, offs and chirps, which are often associated with important behavioral contexts, including aggression, hiding and mating. However, these behaviors are only observed when at least two fish are freely interacting. Although their electrical pulses can be easily recorded by non-invasive techniques, discriminating the emitter of each pulse is challenging when physically similar fish are allowed to freely move and interact. Here we optimized a custom-made software recently designed to identify the emitter of pulses by using automated chirp detection, adaptive threshold for pulse detection and slightly changing how the recorded signals are integrated. With these optimizations, we performed a quantitative analysis of the statistical changes throughout the dominance contest with respect to Inter Pulse Intervals, Chirps and Offs dyads of freely moving Gymnotus carapo. In all dyads, chirps were signatures of subsequent submission, even when they occurred early in the contest. Although offs were observed in both dominant and submissive fish, they were substantially more frequent in submissive individuals, in agreement with the idea from previous studies that offs are electric cues of submission. In general, after the dominance is established the submissive fish significantly changes its average pulse rate, while the pulse rate of the dominant remained unchanged. Additionally, no chirps or offs were observed when two fish were manually kept in direct physical contact, suggesting that these electric behaviors are not automatic responses to physical contact.
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Affiliation(s)
- Rafael T Guariento
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil.
| | | | - Paulo Matias
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
| | - Vinicius B Cesarino
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
| | - Lirio O B Almeida
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
| | - Jan F W Slaets
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
| | - Leonardo P Maia
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
| | - Reynaldo D Pinto
- São Carlos Institute of Physics, University of São Paulo, PO Box 369, 13560-970 São Carlos, SP, Brazil
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