Mechanosensory based orienting behaviors in fluvial and lacustrine populations of mottled sculpin (Cottus bairdi)

Abstract

We compared prey-orienting and rheotactic behaviors in a fluvial (Coweeta Creek) and lacustrine (Lake Michigan) population of mottled sculpin. Blinded sculpin from both populations exhibited unconditioned, mechanosensory based rheotaxis to low velocity flows. Whereas Lake Michigan sculpin generally showed increasing levels of positive rheotaxis to increasing velocities, Coweeta Creek sculpin show varying levels of positive rheotaxis at low to intermediate velocities and often reduced positive rheotaxis or even negative rheotaxis at the highest velocities (12 cm s⁻¹). Blinded Lake Michigan, but not Coweeta Creek mottled sculpin exhibited an orienting response to a small (3 mm diameter) artificial prey (50 Hz vibrating sphere). In conclusion, the two populations differed in the strength and polarity of the rheotactic response at higher velocities and in their responsiveness to mechanosensory cues from epibenthic prey sources. These behavioral differences have most likely arisen from different learning experiences in different habitats and from the greater importance of visual cues to the Coweeta Creek mottled sculpin and mechanosensory cues to Lake Michigan mottled sculpin in the sensory guidance of orienting behaviors.

Keywords:

• Rheotaxis
• prey orientation
• lateral line
• habitat selection
• stream fish
• lake fish

Acknowledgments

The authors thank Jennifer Wasik and Robert Ratajczak for their assistance in collecting animals, conducting behavioral experiments, analyzing data, and maintaining animals. The long-term site access and the logistical support to GG were provided by James Vose, and the staff of the U.S.D.A. Forest Service Coweeta Hydrologic Laboratory. This work was supported by grants from NIH to SC and the U.S.D.A. Forest Service McIntire-Stennis program (GEO-0086-MS) and National Science Foundation (DEB-2018001) to GG. Additional support was provided by the Daniel B. Warnell School of Forest Resources (University of Georgia) and the Parmly Hearing Institute (Loyola University of Chicago). The authors would also like to thank the two anonymous referees for their helpful and constructive comments.