Flow impairs multisensory tracking and increases active sensing in weakly electric fish.

Area of Science:

• Neuroscience
• Animal Behavior
• Sensory Ecology

Background:

• Weakly electric fish use electrosensory, visual, and mechanosensory cues for navigation.
• The impact of water currents on multisensory integration and active sensing in these fish is not well understood.

Purpose of the Study:

• To investigate how ambient flow affects the tracking performance and active sensing of the weakly electric knifefish (Apteronotus albifrons).
• To determine the influence of flow speed, illumination, and refuge structure on tracking accuracy.

Main Methods:

• Knifefish were tested in a flow tunnel tracking a moving refuge under varying flow speeds (0-16 cm/s), light conditions, and refuge types.
• Tracking performance was measured using root-mean-square error (RMSE) and gain-phase analyses.
• Active sensing was quantified by measuring movement power outside stimulus frequencies (mean active sensing power, MASP).

Main Results:

• Increasing flow speed significantly degraded tracking performance, with RMSE increasing by approximately 46% at 16 cm/s.
• Tracking deficits were more pronounced in darkness and with a windowed refuge, particularly at low stimulus frequencies.
• Higher flows led to a trend of increased active sensing power (approximately 33%), suggesting compensatory behavior.

Conclusions:

• Ambient flow acts as hydrodynamic noise, impairing low-frequency tracking in weakly electric fish.
• Knifefish may dynamically reweight sensory inputs and employ compensatory active sensing to maintain navigation in currents.
• Findings highlight context-dependent sensory processing and control strategies in Apteronotus albifrons, linking rheotaxis with electrosensory behaviors.