Effects of fish predation on zooplankton distribution: a preliminary analysis.

Abstract

This study determined the effect of predation on the distributions of Chaoborus americanus and Leptodora kindtii. I put each zooplankton in a tank with one Perca flavescens, yellow perch. Reaction time for the fish to respond to and eat the zooplankton was recorded. A total of five of each zooplantkon was used for each of five fish. A significant difference was observed in the reaction time of the fish to eat Chaoborus versus Leptodora. The Chaoborus was eaten almost five times faster than the Leptodora. Six paired feedings of Chaoborus and Leptodora were also done for each fish. There was a significant difference in the number of times one zooplankton was chosen over the other. Ninety percent of the time Chaoborus was chosen over Leptodora. Paired feedings were also done with stained Chaoborus and Leptodora to determine if the color was a factor in the predation of fish. The zooplankton were stained with Rodamine B. The Chaoborus were totally stained but only the body of the Leptodora stained, leaving its feathery appendages transparent. The Chaoborus were still taken more often than the Leptodora but there were significantly more Leptodora taken when stained than when not stained. This supports the hypothesis that color is a factor in the predation of zooplankton by fish. I concluded that the predation of fish affects the distribution of zooplankton. A possible factor for this predation being the color of the zooplankton.