The effect of container size on the feeding rate of Heterocope septentrionalis, a freshwater predaceous copepod

• Published in: Journal of Plankton Research
• Main Author: O'Brien, W.John
• Format: Text
• Language: English
• Published: Oxford University Press 1988
• Subjects: Articles; Arctic; Copepods
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/10/2/313; https://doi.org/10.1093/plankt/10.2.313

The feeding rates of freshwater predaceous copepods have been measured many times using enclosure experiments. Typically these experiments involve enclosing a known number of zooplanklon prey with a known number of predaceous copepods and determining the number of prey remaining after a set length of time. Various factors such as prey species and size have been shown to influence the feeding rate of copepods. However, little attention has been paid to the influence that container size may have on feeding rates. Using previously published data and some new data it was found that container size has a major impact on the feeding rate of Heterocope septentrionalis , a predaceous freshwater copepod common in North American arctic waters. In experiments with Daphnia puiex , where container size varied from 0.3 to 54 l (180 times), the measured feeding rate coefficient varied from −0.04 to −1.7 (42.5 times). Other prey species showed similar changes, but the vulnerability of particular prey species to Heterocope predation remained consistent across this range of expenmental containers. The reason for the container effect is not known, but it is postulated that edge avoidance by Heterocope may account for the observed change in feeding rate.