STROTHER, James*; KOEHL, M.A.R.; REIDENBACH, Matthew; HADFIELD, Michael G.: Computer simulations of larval behavior in wave-driven flow predict settling usccess in resposne to soluble cues

Can chemical cues in the water affect the settlement of larvae of benthic marine invertebrates in habitats subjected to the wave-driven water flow that characterizes many coastal habitats? We addressed this question using larvae of the sea slug, Phestilla sibogae, which stop swimming and sink in response to a water-borne species-specific metabolite of their prey, Porites compressa. P. compressa are abundant corals that form reefs in shallow, wave-dominated habitats in Hawaii. We measured turbulent water flow above P. compressa reefs in the field and mimicked that flow over a reef constructed in a large flume/wave-tank. We used planar laser-induced fluorescence (PLIF) to visualize the patterns in the water of dye (an analog for cue) leaching from the corals and made video records of the complex patterns of fine filaments of cue swirling above the reef. We used a computer simulation of larvae placed in these PLIF videos to explore the effects of larval behavior on their settlement on the reef in such turbulent wave-driven flow. Our model shows that simply sinking when in a filament of cue can cause larvae to land on the reef, but the proportion of larve that land is affected by various behavioral parameters such as swimming and sinking velocities, sensitivity to cue concentration, and lag time to respond to cue.