Fluxes of Heat and Salt from Endeavour Segment Vent Fields: Discrete Measurements as a Test of the Sea Breeze “flux Meter” Hypothesis

Intellectual Merit . Measurement of the f luxes of heat and materials that t ie geological forcing to biological response is central to addressing the major questions posed in the Endeavour Integrated Study Site implementation plan. We propose to acquire two sets of complementary observations: the vert ical f luxes of f luid mass, heat and sal t r ising from Endeavour Segment vent fields and the lateral t ransport of f luid mass within the axial valley. Taking advantage of the topographic constraints of the Endeavour Segment, we will use these observations to evaluate whether the mean subinert ial component of the lateral fluid flux into the valley balances the upward, buoyancy-driven fluid f lux from the vent f ields–our "sea breeze" hypothesis. A strong correlat ion would provide a means of making continuous, remote proxy measurements of the integrated f luxes from the vent f ields, thereby serving as a “flux meter .” A variety of preliminary data indicate that lateral transport exists and is of the expected magnitude. In addit ion to test ing the sea breeze hypothesis, the data would help address a number of other significant questions concerning the how the flux of heat from Endeavour Segment evolves, the rates of change associated with phase separation and segregation, f luxes of substrates used as energy sources by plume microbiota, and characterist ics of the regional circulat ion relevant to larval dispersal .