Environmental conditions measured at colonization surfaces or on seafloor.

Measurements recorded at 9, 11, 22 or 23 months after the eruption, during cruises in October 2006, December 2006, and November/December 2007 respectively, and pre-eruption (Pre) in December 1995. Sites were vents in the region of 9°50′N East Pacific Rise (Fig. 1), habitats were characterized as hot (H), warm (W) or cool (C) on initial visit. Temperature (T) was measured directly at colonization surfaces with Alvin probe. Temperature, pH and free sulfide (sul) were measured at the seafloor with electrochemical sensors in the vicinity of colonization surfaces and at other nearby vents (N = number of measurements in each habitat type).