Light as a proximate cue for the vertical migration of the zooplankton Chaoborus flavicans in Lancaster Lake, Michigan.

Abstract

The purpose of this experiment was to study light as a proximate cue for the vertical migration of the zooplankton Chaoborus flavicans, in Lancaster Lake, Cheboygan County, Michigan (T37N, R3W, sections 5 and 8). We began the experiment on July 31 through August 1. We placed ten C. flavicans in six different 1000 ml Pyrex graduated cylinders. Three were placed in a continually dark room (treatment) and the other three were placed in a room with a 60 watts incandescent light bulb placed above them. The light simulated day and night, being turned on at sunrise (0600 h) and turned off at near sunset (1900 h). The cylinders were checked at noon and midnight. We counted the number of C. flavicans in five 7 cm sections. We found that the distributions between control and treatment were insignificant at midnight, but the distributions between control and treatment at noon and between noon and midnight for the control and treatment were significantly different. We found that C. flavicans exhibited positive phototaxis which is not consistent with other findings. Our results indicated that light may not be the sole cue for vertical migration.