Most zooplankton undergo diel vertical migration (DVM) at some stage of development. The common pattern involves an ascent near sunset and descent near sunrise. The most pervasive functional explanations are the animals rise to feed at night and descend to avoid visually-oriented predators during the day. Recent studies indicate the presence and absence of planktivores can alter DVM through rapid behavioral changes. Since light is the most important cue for DVM, alterations in migration by cues from predators should involve changes in photoresponses. The research objectives in Dr. Forward's investigation are (1) to determine whether photoresponses involved in DVM are altered by the presence or absence of visually- and nonvisually-directed predators, and (2) to determine whether chemical, visual and/or mechanical cues from predators induce alterations in zooplankton photoresponses. These studies will make a significant contribution to our basic understanding of zooplankton sensory biology and interactions with predators.
