https://dx.doi.org/10.1023/A:1021046431482">
 

Abstract

I describe a laboratory system for investigating the role of light as a proximate cue for diel changes in locomotor activity and vertical location on the substrate of stream macro-invertebrates. The system consisted of computer-controlled halogen lamps positioned over a laboratory stream in which video-recordings were made of Stenonema modestum mayfly nymphs located on the undersides of unglazed tile substrates. Locomotor activity of study organisms in response to light changes were quantified during computer-programmed and reproducible light/dark (LD) cycles. The system provided the flexibility to simulate a variety of light environments so that the separate influences of light intensity and light change on diel activities of individuals and populations could be examined, which is difficult under natural light conditions. As a group, nymphs responded similarly to simulated twilight (light decrease from 7.9 × 102 to 6.9 × 10−2 μW cm−2 at a constant –1.9 × 10−3 s−1 rate of relative light change) and to natural twilight, suggesting that proposed mechanisms of light control of diel activities in nature can be adequately tested in the simulated environment. However, locomotor activity and vertical movements among individual mayflies were highly variable under controlled conditions, suggesting that physiological differences influence their responses to environmental conditions.

Department

Earth Systems Research Center

Publication Date

7-1-2002

Journal Title

Hydrobiologia

Publisher

Springer

Digital Object Identifier (DOI)

https://dx.doi.org/10.1023/A:1021046431482

Document Type

Article

Rights

Copyright © 2002, Kluwer Academic Publishers

Comments

This is an Accepted Manuscript. The final publication is available at Springer via https://dx.doi.org/10.1023/A:1021046431482

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