Habitability of ultrabasic, serpentinite-associated waters from coast range and Philippines ophiolites
The deep biosphere in cold, dark sub-seafloor ultramafic rocks ( i.e., those rocks rich in Fe and Mg) is stressed by exceedingly high pH, transient, if any, inorganic carbon availability, and little known organic carbon inventories. As a test of heterotrophic carbon use, serpentinite-associated waters (from groundwater sampling wells and associated surface seepages in tectonically uplifted mantle units in ophiolites) were tested for differences with respect to aqueous geochemistry and performance in EcoPlates™ - BioLog Inc. This work focuses on two field locations for water sampling: the Coast Range Ophiolite, CA, USA, and the Zambales Ophiolite, Philippines. Characteristics of each sampling site are presented (pH, ORP, Conductivity, temperature, lithology, %DO, depth, and Ca2+/Mg2+ ratios). Complementary EcoPlate ™ results [prefabricated 96-well plates, seeded with triplicate experiments for determining microbiological community response to difference organic carbon sources; a triplicate control experiment with no carbon source is built in to the plate] are also presented. We found that waters from selected California [groundwater wells (7 discrete wells) and related surface seeps (5 hydrologically connected sites)] and Philippines [4 Zambales Ophiolite springs/seepages] sourced in serpentinites were analyzed. EcoPlate ™ average well-color development (AWCD), which demonstrates microbial activities averaged per plate (as in Garland and Mills, 1991), differs across sites. Correlations of AWCD with environmental data are evaluated. Clarifying the geochemical-biological relationships that bear out in these analyses informs discourse on the energetic limits of life in serpentinizing systems, with relevance to ultramafic-hosted life on continents and in the seabed.
Tabetha Juliann Scott,
"Habitability of ultrabasic, serpentinite-associated waters from coast range and Philippines ophiolites"
Dissertations and Master's Theses (Campus Access).