Abstract
The effects of clay turbidity and light on the predatorprey interaction between planktivorous smelts (Osmerus eperlanus) and phantom midge (Chaoborus flavicans) larvae were studied by means of laboratory experiments. Irrespective of light intensity, fish-mediated mortality of chaoborid larvae was highest at intermediate turbidity (20 nephelometric turbidity units (NTU)). Increases in light intensity enhanced the feeding rate of smelts at very low light intensities. A regression model describing the dependence of smelt-mediated mortality of chaoborids on light intensity and turbidity was fitted to the data. The model suggested that turbidity exceeding 30 NTU combined with light intensity below 0.1 µE·m2·s1provides an efficient daytime refuge for chaoborids even in the presence of planktivorous smelts. In the field studies, the depth distribution of chaoborids followed the predictions of the model. The depth at which chaoborid density was highest depended on the existence and location of the thermocline, the densest swarms occurring beneath the turbidity maximum in the metalimnion. The smelts occupied water layers above the chaoborids, suggesting that the chaoborids used the steep turbidity gradient in the thermocline as a shelter against predation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: Canadian Journal of Fisheries and Aquatic Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.