Active Positioning of Vent Larvae at a Mid-Ocean Ridge

The vertical position of larvae of vent species above a mid-ocean ridge potentially has a strong effect on their dispersal. We found evidence for active larval positioning in a comparison between field observations of larvae above vents near 9° 50’N on the East Pacific Rise, and distributions of non-swimming larvae in a two-dimensional bio-physical model. In the field, few vent larvae were collected at the level of the neutrally buoyant plume (~75 m above bottom); their relative abundances at that height were much lower than those of simulated larvae from a near-bottom release in the model. This discrepancy was observed for many vent species, particularly gastropods, suggesting that they may actively remain near bottom by sinking or swimming downward. Near the seafloor, larval abundance decreased from the ridge axis to 1000 m off axis much more strongly in the observations than in the simulations, again pointing to behavior as a potential regulator of larval transport. We suspect that transport off axis was reduced by downward-moving behavior, which positioned larvae into locations where they were isolated from cross-ridge currents by seafloor topography - such as the walls of the axial valley – which are not resolved in the model. Cross-ridge gradients in larval abundance varied between gastropods and polychaetes, indicating that behavior may vary between taxonomic groups, and possibly between species. These results suggest that behaviorally mediated retention of vent larvae may be common, even for species that have a long planktonic larval duration and are capable of long-distance dispersal.

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First Name: 
Lauren
Last Name: 
Mullineaux
Telephone: 
508 289 2898
Affiliation: 
Biology Department, Woods Hole Oceanographic Institution
First Name: 
Dennis J.
Last Name: 
McGillicuddy, Jr.
Affiliation: 
Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution
First Name: 
Susan W.
Last Name: 
Mills
Affiliation: 
Biology Department, Woods Hole Oceanographic Institution Woods Hole, MA 02543
First Name: 
Andreas M.
Last Name: 
Thurnherr
Affiliation: 
Division of Ocean and Climate Physics, Lamont-Doherty Earth Observatory,
First Name: 
Jim R.
Last Name: 
Ledwell
Affiliation: 
Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution
First Name: 
J. W.
Last Name: 
Lavelle
Affiliation: 
NOAA/Pacific Marine Environmental Laboratory
Choose keywords that are most applicable to your abstract. (Three maximum.): 
Distribution and abundance
Early life history (reproduction, dispersal, settlement, recruitment)
Abstract ID: 
CBE5-139