scholarly journals Seasonal and social factors associated with spacing in a wild territorial electric fish

2020 ◽  
Author(s):  
Lucía Zubizarreta ◽  
Laura Quintana ◽  
Daniel Hernández ◽  
Franco Teixeira de Mello ◽  
Mariana Meerhoff ◽  
...  
Keyword(s):  
Body Size ◽  
Dissolved Oxygen ◽  
Breeding Season ◽  
Electric Fish ◽  
Behavioral Plasticity ◽  
Gonadal Hormones ◽  
Social Contexts ◽  
Weakly Electric Fish ◽  
Territory Size ◽  
Wide Range

AbstractThe expression of territorial behavior in wild species is especially suited to explore how animals integrate individual traits with dynamic environmental and social contexts. In this study, we focused on the seasonal variation of the determinants of territory size in the weakly electric fish Gymnotus omarorum. This species is a seasonal breeder that displays year-long territorial aggression, in which female and male dyads exhibit indistinguishable non-breeding territorial agonistic behavior and the only significant predictor of contest outcome is body size. We carried out field surveys across seasons that included the identification of individual location, measurements of water physico-chemical variables, characterization of individual morphometric and physiological traits, and their correlation to spatial distribution. Although Gymnotus omarorum tolerates a wide range of dissolved oxygen concentration, territory size correlated with dissolved oxygen in both seasons. In the non-breeding season, we show that territory size is sexually monomorphic and explained only by body size. In the breeding season, while body size no longer correlated with territory size, evidence of sexual differences in territory size determinants emerged. First, the overall spatial arrangement adopted a sexual bias. Second, territory size depended on gonadal hormones in both sexes, which was expected for males, but not previously reported in females. Third, females’ territory size correlated with gonadal size and females showed relatively larger territories than males, probably to meet sexually dimorphic energetic requirements. This study provides evidence of seasonal changes in factors correlated with territory size and contributes to the understanding of the mechanisms underlying behavioral plasticity.

scholarly journals Electric signal synchronization as a behavioural strategy to generate social attention in small groups of mormyrid weakly electric fish and a mobile fish robot

2021 ◽  
Author(s):  
Martin Worm ◽  
Tim Landgraf ◽  
Gerhard von der Emde
Keyword(s):  
Small Groups ◽  
Electric Fish ◽  
Social Attention ◽  
Weakly Electric Fish ◽  
Electric Signal ◽  
Fish Robot ◽  
Wide Range ◽  
Signal Synchronization ◽  
Weakly Electric ◽  
Attention Hypothesis

AbstractAfrican weakly electric fish communicate at night by constantly emitting and perceiving brief electrical signals (electric organ discharges, EOD) at variable inter-discharge intervals (IDI). While the waveform of single EODs contains information about the sender’s identity, the variable IDI patterns convey information about its current motivational and behavioural state. Pairs of fish can synchronize their EODs to each other via echo responses, and we have previously formulated a ‘social attention hypothesis’ stating that fish use echo responses to address specific individuals and establish brief dyadic communication frameworks within a group. Here, we employed a mobile fish robot to investigate the behaviour of small groups of up to four Mormyrus rume and characterized the social situations during which synchronizations occurred. An EOD-emitting robot reliably evoked social following behaviour, which was strongest in smaller groups and declined with increasing group size. We did not find significant differences in motor behaviour of M. rume with either an interactive playback (echo response) or a random control playback by the robot. Still, the robot reliably elicited mutual synchronizations with other fish. Synchronizations mostly occurred during relatively close social interactions, usually when the fish that initiated synchronization approached either the robot or another fish from a distance. The results support our social attention hypothesis and suggest that electric signal synchronization might facilitate the exchange of social information during a wide range of social behaviours from aggressive territorial displays to shoaling and even cooperative hunting in some mormyrids.

Non-breeding territoriality and the effect of territory size on aggression in the weakly electric fish, Gymnotus omarorum

2019 ◽  
Vol 22 (2) ◽  
pp. 79-89 ◽  
Author(s):  
Rossana Perrone ◽  
Federico Pedraja ◽  
Guillermo Valiño ◽  
Bettina Tassino ◽  
Ana Silva
Keyword(s):  
Electric Fish ◽  
Weakly Electric Fish ◽  
Territory Size ◽  
Weakly Electric

scholarly journals Calcium Dynamics Encode the Magnitude of a Graded Memory Underlying Sensorimotor Adaptation

2010 ◽  
Vol 103 (5) ◽  
pp. 2372-2381 ◽  
Author(s):  
Nikolai C. Dembrow ◽  
Diana L. Pettit ◽  
Harold H. Zakon
Keyword(s):  
Electric Fish ◽  
Neural Correlates ◽  
Weakly Electric Fish ◽  
Intrinsic Excitability ◽  
Sensorimotor Adaptation ◽  
Neural Correlate ◽  
Wide Range ◽  
Excitability Of Neurons ◽  
Weakly Electric

The role of Ca2+ in the induction of neural correlates of memory has frequently been described in binary terms despite the fact that many forms of memory are graded in their strength and/or persistence. We find that Ca2+ dynamics encode the magnitude of sensorimotor adaptation of the electromotor output in a weakly electric fish. The neural correlate of this memory is a synaptically induced Ca2+-dependent enhancement of intrinsic excitability of neurons responsible for setting the electromotor output. Changes in Ca2+ during induction accurately predict the magnitude of this graded memory over a wide range of stimuli. Thus despite operating over a range from seconds to tens of minutes, the encoding of graded memory can be mediated by a relatively simple cellular mechanism.

Allometric and environmental correlates of territory size in juvenile Atlantic salmon (Salmo salar)

1995 ◽  
Vol 52 (1) ◽  
pp. 186-196 ◽  
Author(s):  
Ernest R. Keeley ◽  
James W. A. Grant
Keyword(s):  
Body Size ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Territory Size ◽  
Environmental Correlates ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Wide Range ◽  
Body Sizes ◽  
Young Of The Year

We observed juvenile Atlantic salmon (Salmo salar) over a wide range of stream conditions and body sizes to determine the relative importance of environmental factors and body size as predictors of territory size. Defended and foraging areas were virtually identical in size. Eighty-eight percent of the variation in territory size was explained by differences in body size and age; territory size increased with body size, but young-of-the-year salmon had relatively larger territories for their body size than older fish. Territory size was inversely related to food abundance, the only significant environmental correlate of territory size, but food only explained an additional 2% of the variation in territory size. Intruder pressure, visual isolation, and current velocity were not significantly related to territory size. The allometric scaling of territory size was consistent with the hypothesis that Atlantic salmon maintain a maximum daily ration of drift flowing over their territory. Atlantic salmon in Catamaran Brook have larger territories than is reported in the literature for other stream-dwelling salmonids of a similar size.

scholarly journals The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia

2021 ◽  
Author(s):  
Stefan Mucha ◽  
Lauren J. Chapman ◽  
Rüdiger Krahe
Keyword(s):  
Active Avoidance ◽  
Electric Fish ◽  
Electric Organ ◽  
The Other ◽  
Weakly Electric Fish ◽  
Dissolved Oxygen Concentration ◽  
Shuttle Box ◽  
Freshwater Habitats ◽  
Electric Organ Discharges ◽  
Weakly Electric

AbstractAnthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.

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