Electric organ discharge frequency and plasma sex steroid levels during gonadal recrudescence in a natural population of the weakly electric fish Sternopygus macrurus

1991 ◽  
Vol 169 (4) ◽  
Author(s):  
HaroldH. Zakon ◽  
Peter Thomas ◽  
Hong-Young Yan
Keyword(s):  
Natural Population ◽  
Electric Fish ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Discharge Frequency ◽  
Sex Steroid ◽  
Gonadal Recrudescence ◽  
Weakly Electric ◽  
Electric Organ Discharge Frequency

scholarly journals The weakly electric fish, Apteronotus albifrons, avoids hypoxia before it reaches critical levels

2020 ◽  
Author(s):  
Stefan Mucha ◽  
Lauren J. Chapman ◽  
Rüdiger Krahe
Keyword(s):  
Electric Fish ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
Swimming Activity ◽  
Weakly Electric Fish ◽  
Dissolved Oxygen Concentration ◽  
Freshwater Habitats ◽  
Electric Organ Discharges ◽  
Weakly Electric ◽  
Electric Organ Discharge Frequency

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. Below 22% air saturation, A. albifrons actively avoided the hypoxic compartment. 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.SummaryThe weakly electric knifefish, Apteronotus albifrons, avoids hypoxia below 22% air saturation. Avoidance correlates with increased swimming activity, but not with a change in electric organ discharge frequency.

scholarly journals Electrical signalling of dominance in a wild population of electric fish

2010 ◽  
Vol 7 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Vincent Fugère ◽  
Hernán Ortega ◽  
Rüdiger Krahe
Keyword(s):  
High Frequency ◽  
Electric Fish ◽  
Electric Organ Discharge ◽  
Low Frequency ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Dominance Status ◽  
Strong Positive Relationship ◽  
Electrical Signalling ◽  
Weakly Electric

Animals often use signals to communicate their dominance status and avoid the costs of combat. We investigated whether the frequency of the electric organ discharge (EOD) of the weakly electric fish, Sternarchorhynchus sp., signals the dominance status of individuals. We correlated EOD frequency with body size and found a strong positive relationship. We then performed a competition experiment in which we found that higher frequency individuals were dominant over lower frequency ones. Finally, we conducted an electrical playback experiment and found that subjects more readily approached and attacked the stimulus electrodes when they played low-frequency signals than high-frequency ones. We propose that EOD frequency communicates dominance status in this gymnotiform species.

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