Meeting Abstract

89.4  Thursday, Jan. 7  Effects of wall compliance on swimbladder function in zebrafish CROLL, R.P.*; STOYEK, M.R.; SMITH, F.M.; Dalhousie Univ; Dalhousie Univ; Dalhousie Univ roger.croll@dal.ca

Zebrafish use gas-filled swimbladders to attain nearly neutral buoyancy, contribute to three-dimensional orientation (pitch and roll), and facilitate hearing (via the Weberian apparatus). However, swimbladder volume varies with depth-related pressure according to Boyle’s Law and also depends on the viscoelastic properties of its wall. In this study the effects of pressure on swimbladder volume, both in vivo and in situ, were observed along with the behaviour of the whole animal, using pressure chambers to simulation vertical movements to and from a depth of 300 cm within the water column. The anterior chamber was found to be highly compliant with large volume changes accomplished in part through a series of regular pleating of its wall. In contrast, the posterior chamber was found to be minimally compliant. These regional differences in compliance caused significant changes in the distribution of gas within the swimbladder system, but the whole-body pitch angle changed only ±2o over the tested range of pressure tested. Ongoing experiments on zebrafish hearing have shown repeatable increases in swimming activity (arousal) in adult zebrafish during exposure to sound stimuli. Comparison of the results of these tests to zebrafish tested after simulated depth changes will elucidate any effects that changes in swimbladder volume may have on audition. It is assumed that our observations on swimbladder compliance and its effects on function are similar to what zebrafish would experience in their natural environment thereby adding a much needed link to existing experimental knowledge of the zebrafish.