The discovery in April , 1991 of newly-formed hydrothermal vents located in areas of recent and intense volcanic activity between 9o45' and 9o52'N along the East Pacific Rise (EPR) affords, for the first time, the opportunity to follow biological and geological changes over time from the apparent "birth" of a number of deep-sea hydrothermal vents. Observations and measurements made using the submersible Alvin in March, 1992, 11 months after an active eruptive event, have indicated dramatic changes in geological features, vent fluid geochemistry and biological community structure over the 11-month period since the eruptive events was observed on the seafloor in the region. During the March, 1992 cruise, 210 markers were deployed along a 1.4 km stretch of the axial summit caldera (ASC) of the EPR between 9o49.61' and 9o50.36'N. The resulting transect, which traversed numerous active vent areas, was extensively documented utilizing a variety of 35 mm, electronic still camera, and Hi-8 video capabilities. The primary objective of this study is to document over a 3-year period temporal changes in biological community structure and associated geological features observed along this active segment of the mid-oceanic ridge axis. The approach involves a combination of: (1) numerous 35 mm, Hi-8 video, and electronic still camera (ESC) imaging surveys along the recently marked 1.4 km stretch of the ASC; and (2) long term time-lapse photography (Hi-8 video) at three-designated "sanctuaries" within this hydrothermally active region of the ASC.
