Abstract
The effects of larval density and age on pre-settlement swimming behaviour of Balanus amphitrite cyprid larvae were studied with the aid of computer-assisted motion analysis. Swimming behaviour was monitored in individual, in groups of 10–15 and in groups of 50–100 cyprids. There was a small, but significant effect of larval density on swimming speed and no effect on two other quantitative measures: rate of change of direction and net-to-gross displacement ratio. There was also small but significant variation in swimming speed between different batches of cyprids over the course of 2 years. Swimming behaviour of individual cyprid larvae was also monitored daily for 7 days, with the larvae maintained in the cold and dark between measurements to prevent settlement and metamorphosis. There were no significant behavioural differences observed over time indicating that larvae may be held in this manner experimentally without affecting these parameters.
Acknowledgments
The authors are grateful to Stephen Greer for his assistance with the statistical analyses and to two anonymous reviewers for constructive comments on an earlier version of the manuscript. This work was funded in part by J.B.M.'s Polar and Marine Biology Endowed Professorship and by the National Oceanic and Atmospheric Administration (NOAA), the US Department of Commerce under grant no. R/MT-40 to C.D.A. and J.B.M., the Mississippi–Alabama Sea Grant Consortium, and the University of Alabama at Birmingham. The US Government is authorized to produce and distribute reprints notwithstanding any copyright notation that may appear hereon. The views expressed herein are those of the authors and do not necessarily reflect the views of NOAA or its subagencies.