This project will advance the development of an in-situ sensor package designed to quantify the spatial and temporal variation of environmental parameters and associated microbial communities within submarine hydrothermal systems. The ultimate goals of this project are to determine under in-situ conditions the upper temperature limit of life, what environmental parameters may promote growth under these conditions and what consortia are present. This project builds on the successful field testing of three prototype sulfide microbial incubators within the Mothra and Main Endeavour vent fields on the Juan de Fuca Ridge. Questions to be addressed include: What thermal gradients are present within the walls of mature, diffusely venting edifices? What is the hydrogen fugacity and oxidation state of fluids within the chimney walls? What is the maximum growth and survival temperature of natural microbial communities and of representative isolated cultures of hyperthermophiles within active vents? What is the naturally occurring phylogenetic and physiological diversity of hyperthermophiles in mature, diffusely venting sulfide structures?
