Hot vent fluid enters the ocean at high-temperature hydrothermal vents, also known as black smokers. Because of the large temperature difference between the vent fluid and oceanic near-bottom waters, the hydrothermal effluent initially rises as a buoyant plume through the water column. During its rise, the plume engulfs and mixes with background ocean water. This process, called entrainment, gradually reduces the density of the rising plume until it reaches its level of neutral buoyancy, where the plume density equals that of the background water, and it begins to spread along a surface of constant density. (For a much more detailed discussion of buoyant hydrothermal plumes, see Di Iorio et al., 2012, in this issue.)

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Jackson, P.R., J.R. Ledwell, and A.M. Thurnherr. 2010. Dispersion of a tracer on the East Pacific Rise (9°N to 10°N), including the influence of hydrothermal plumes. Deep Sea Research Part I 57:37–52, https://doi.org/10.1016/j.dsr.2009.10.011.

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McGillicuddy, D.J., J.W. Lavelle, A.M. Thurnherr, V.K. Kosnyrev, and L.S. Mullineaux. 2010. Larval dispersion along an axially symmetric mid-ocean ridge. Deep Sea Research Part I 57:880–892, https://doi.org/10.1016/j.dsr.2010.04.003.

Thurnherr, A.M., and L.C. St. Laurent. 2011. Turbulence and diapycnal mixing over the East Pacific Rise crest near 10°N. Geophysical Research Letters 38, L15613, https://doi.org/10.1029/2011GL048207.

Thurnherr, A.M., J.R. Ledwell, J.W. Lavelle, and L.S. Mullineaux. 2011. Hydrography and circulation near the crest of the East Pacific Rise between 9° and 10°N. Deep Sea Research Part I 58:365–376, https://doi.org/10.1016/j.dsr.2011.01.009.

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