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Hadfield & Koehl - Larval settlement in response to soluble cues from the benthos

Larval settlement in response to soluble cues from the benthos

Michael G. Hadfield1 and Mimi A. R. Koehl2

1 Kewalo Marine Laboratory, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, hadfield@hawaii.edu

2 Department of Integrative Biology, University of California, Berkeley, CA 94270

In laboratory studies, larvae of many benthic marine animals settle and metamorphose in response to dissolved chemical cues released by benthic organisms. Veligers of the nudibranch Phestilla sibogaewere used to investigate whether such cues induce sufficiently rapid behavioral responses to bring about settlement near suitable recruitment sites, in this case their postmetamorphic prey, Porites compressa, an abundant coral on reefs in shallow, wave-dominated habitats in Hawaii. Video analyses of trajectories and speeds of larvae swimming mid-water in aquaria revealed that larvae tend to cease swimming and sink in water conditioned by P. compressa. As cue and larvae are mixed in the turbulent flow over a coral reef, the fine-scale filamentous structure of cue concentrations in the water column translate into rapid (seconds) on/off temporal patterns of cue encountered by microscopic larvae. Larvae tethered in a miniflume and exposed to water velocities mimicking flow past freely swimming larvae were videotaped while exposed to realistic temporal patterns of cue filaments. Larvae quickly retracted the velum and ceased swimming in filaments of cue and resumed swimming when they passed out of them, actions sufficient to bring rapid settlement onto the reef. Analyses of the data derived from these studies provided a model that predicts settlement over fore- and mid-reef areas. The prediction has been tested and found to be valid.


next up previous
Next: Leighton & Sawyer - Up: Special Symposium - From Previous: Goodwin - You Can
Peter Roopnarine 2005-04-12