Absolute light intensity vs. rate of relative change in light intensity: the role of light in the vertical migration of Chaoborus punctipennis larvae


Journal Article

Fourth-instar Chaoborus punctipennis larvae exhibited a light-induced positive geotaxis at high light intensity (>1.3.10-5.Wm-2) and a light-induced negative geotaxis at low light intensity (<3.10-6.Wm-2) when stimulated with light filtered to match their spectral sensitivity. Phototaxis was not observed under conditions which simulated the natural underwater angular light distribution. In the field, larvae ascended near the time of sunset and descended near sunrise. At dusk the population peak occurred at each sampling depth when the average light intensity there was 3.10-7.Wm-2. At dawn the population peak migrated down just ahead of the threshold intensity for positive geotaxis (1.3.10-5.Wm-2). The migration pattern can be explained as a simple response to absolute light intensity. Upward and downward movement of the population occurs at ambient light intensities just below the respective "threshold' intensities for negative and positive geotaxis. The initiating cue is absolute light intensity and the orienting cue is gravity. -from Authors

Duke Authors

Cited Authors

  • Swift, MC; Forward, RB

Published Date

  • January 1, 1988

Published In

Volume / Issue

  • 43 / 3

Start / End Page

  • 604 - 619

International Standard Serial Number (ISSN)

  • 0007-4977

Citation Source

  • Scopus