Low-temperature (typically 5–75°C) fluid, commonly referred to as “diffuse” hydrothermal flow, emanates from fractures over a significant portion of the Juan de Fuca Ridge seafloor in the Northeast Pacific Ocean (Kelley et al., 2012, in this issue). Although some fraction of the diffuse effluent becomes entrained relatively quickly into nearby plumes from high-temperature sources, a number of studies suggest that a significant portion flows laterally as discrete low-level plumes that remain detectable downstream for considerable distances (Trivett and Williams, 1994; Kinoshita et al., 1998, Veirs et al., 2006). The seafloor near diffuse hydrothermal vents supports densely populated, localized biological communities in a bottom boundary layer (BBL) environment that is highly variable in both space and time. Currents, temperature, and turbulence in the BBL, in addition to a complex array of biological, chemical, geological, and other physical factors, influence community structure near diffuse vents. Tides strongly affect the flow direction of both high-temperature (Veirs et al., 2006) and diffuse (Kinoshita et al., 1998) plumes within the water column, and have been observed to affect temperature in the immediate vicinity of diffuse vents (Little et al., 1988; Tivey et al., 2002; Sheirer at al., 2006). Here, we describe recent measurements that reveal in greater detail the important role that tidal advection plays in modulating the BBL environment near diffuse hydrothermal plumes.

Hautala, S., H.P. Johnson, M. Pruis, I. García-Berdeal, and T. Bjorklund. 2012. Low-temperature hydrothermal plumes in the near-bottom boundary layer at Endeavour Segment, Juan de Fuca Ridge. Oceanography 25(1):192–195, https://doi.org/10.5670/oceanog.2012.17.

García-Berdeal, I. 2006. Hydrography and flow in the axial valley of the Endeavour Segment: Implications for larval dispersal. PhD Dissertation, University of Washington, Seattle.
1. Johnson, H.P., S.L. Hautala, M.A. Tivey, C.D. Jones, J. Voight, M. Pruis, I. García-Berdeal, L.A. Gilbert, T. Bjorklund, W. Fredericks, J. Howland, and the Thermal Grid Scientific Party. 2002. A systematic examination of hydrothermal circulation: Endeavour Segment, Juan de Fuca Ridge. Eos, Transactions, American Geophysical Union 83:73, 78.
2. Kelley, D.S., S.M. Carbotte, D.W. Caress, D.A. Clague, J.R. Delaney, J.B. Gill, H. Hadaway, J.F. Holden, E.E.E. Hooft, J.P. Kellogg, and others. 2012. Endeavour Segment of the Juan de Fuca Ridge: One of the most remarkable places on Earth. Oceanography 25(1):44–61, https://doi.org/10.5670/oceanog.2012.03.
3. Kinoshita, M., R.P. Von Herzen, O. Matsubayashi, and K. Fujioka. 1998. Tidally-driven effluent detected by long-term temperature monitoring at the TAG hydrothermal mound, Mid-Atlantic Ridge. Physics of the Earth and Planetary Interiors 108:143–154, https://doi.org/10.1016/S0031-9201(98)00092-2.
4. Little, S.A., K.D. Stolzenbach, and F.J. Grassle. 1988. Tidal current effects on temperature in diffuse hydrothermal flow: Guaymas Basin. Geophysical Research Letters 15:1,491–1,494, https://doi.org/10.1029/GL015i013p01491.
5. Pruis, M.J. 2004. Energy and volume flux into the deep ocean: Examining diffuse hydrothermal systems. PhD Dissertation, University of Washington, Seattle.
6. Scheirer, D.S., T.M. Shank, and D.J. Fornari. 2006. Temperature variations at diffuse and focused flow hydrothermal vent sites along the northern East Pacific Rise. Geochemistry Geophysics Geosystems 7, Q03002, https://doi.org/10.1029/2005GC001094.
7. Tivey, M.K., A.M. Bradley, T.M. Joyce, and D. Kadko. 2002. Insights into tide-related variability at seafloor hydrothermal vents from time-series temperature measurements. Earth and Planetary Science Letters 202:693–707, https://doi.org/10.1016/S0012-821X(02)00801-4.
8. Trivett, D.A., and A.J. Williams III. 1994. Effluent from diffuse hydrothermal venting: 2. Measurements of plumes from diffuse hydrothermal vents at the southern Juan de Fuca Ridge. Journal of Geophysical Research 99:18,417–18,432.
9. Veirs, S.R., R.E. McDuff, and F.R. Stahr. 2006. Magnitude and variance of near-bottom horizontal heat flux at the Main Endeavour hydrothermal vent field. Geochemistry Geophysics Geosystems 7, Q02004, https://doi.org/10.1029/2005GC000952.

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