Dispersion of a tracer on the East Pacific Rise (9N to 10N), including the influence of hydrothermal plumes

P. R. Jackson, J. R. Ledwell, A. M. Thurnherr

Research output: Contribution to journalArticlepeer-review


On 12 November 2006, 3 kg of sulfur hexafluoride were released in a 1.2 km long streak in the axial summit trough of the East Pacific Rise at 9°30′N to study how circulation and mixing affect larval dispersion. The first half of a tracer survey performed approximately 40 days after the injection found a small percentage of the tracer on the ridge axis between 9°30′N and 10°10′N, with the main concentration near 9°50′N, a site of many active hydrothermal vents. These observations provide evidence of larval connectivity between vent sites on the ridge. The latter half of the survey detected the primary patch of tracer west of the ridge and just south of the Lamont Seamounts, as a majority of the tracer had been transported off the ridge. However, by the end of the survey, the eastern edge of this patch was transported back to within 10 km of the ridge crest at 9°50′N by a reversal in the subinertial flow, suggesting another pathway for larvae between points along the ridge. Both the horizontal and vertical distributions of the tracer were complex and were likely heavily influenced by topography and vents in the area. Elevated tracer concentrations within the axial summit trough and an adjacent depression on the upper ridge flank suggest that tracers may be detained in such depressions. Correlated tracer/turbidity profiles provide direct evidence of entrainment of the tracer into vent plumes from 9°30′N to 10°N. A comparison of the vertical tracer inventory with neutral density vent-plume observations suggests that on the order of 10% of the tracer injected was entrained into vent plumes near the injection site. The results imply that effluent from diffuse hydrothermal sources and larvae of hydrothermal vent fauna can be entrained in significant quantities into plumes from discrete sources and dispersed in the neutrally buoyant plumes.

Original languageEnglish (US)
Pages (from-to)37-52
Number of pages16
JournalDeep-Sea Research Part I: Oceanographic Research Papers
Issue number1
StatePublished - Jan 2010


  • ISWS
  • East Pacific Rise
  • Hydrothermal vent plume
  • Tracer experiment
  • Larval transport
  • Ocean mixing

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography


Dive into the research topics of 'Dispersion of a tracer on the East Pacific Rise (9N to 10N), including the influence of hydrothermal plumes'. Together they form a unique fingerprint.

Cite this