Vertical migration in Chaoborus flavicans in the absence and presence of diel light cycles.

Abstract

Diel vertical migration in zooplankton communities has been extensively studied for well over a century, yet factors affecting this phenomenon are not well understood. Light as a cue for vertical migration in the dipteran Chaoborus flavicans was examined under laboratory conditions. Our results indicate that Chaoborus experiencing a diel light cycle exhibit reverse vertical migration, and Chaoborus kept continually in the dark exhibit a reduced normal vertical migration pattern. Previous studies have shown that Chaoborus in the field follow a normal diel vertical migration pattern. Our results can be explained by many factors, such a light quality, hunger, predation pressures and endogenous rhythms. We concluded that light does induce vertical migration, however, that cue is modified by many factors.