CHEMICAL INDUCTION OF LARVAL SETTLEMENT BEHAVIOR IN FLOW

The ability of dissolved chemical cues to induce larval settlement fro m the water column has long been debated. Through computer-assisted vi deo motion analysis, we quantified the movements of individual oyster (Crassostrea virginica) larvae in a small racetrack flume at free-stre am flow speeds of 2.8, 6.2, and 10.4 cm/s, In response to waterborne c hemical cues, but not to seawater (control), oyster larvae moved downw ard in the water column and swam in slow curved paths before attaching to the flume bottom. Effective stimuli were adult-oyster-conditioned seawater (OCW) and a synthetic peptide analog (glycyl-glycyl-L-arginin e) for the natural cue. The chemically mediated behavioral responses o f oyster larvae in flow were essentially identical to those responses previously reported in still water. Our experimental results therefore demonstrate the capacity of waterborne cues to evoke settlement behav ior in oyster pediveligers under varying hydrodynamic conditions.