Collaborative Research: Modeling Hyperthermophile Growth in Deep-Sea Hydrothermal Sulfide Deposits and Diffuse Fluids

University Of Washington, Seattle WA

Investigators

Abstract

Deep-sea hydrothermal fluids circulate through vast portions of the earth?s crust. Volcanically derived gases and products from water-rock reactions support chemolithoautotrophic microbial communities that might be pervasive within the subseafloor and contribute significantly to deep-ocean and subseafloor biomass production. Microorganisms in low-temperature terrestrial environments are commonly segregated by metabolism along chemical gradients. However, demonstration of a similar distribution pattern of organisms along geochemical gradients in deep-sea geothermal environments to date has been rare. The use of hyperthermophiles for such a study is ideal since these organisms are generally not found in contaminating background seawater and since their metabolisms likely reflect the chemistry and temperature of their environment. Understanding the distribution of different types of chemolithoautotrophic hyperthermophiles in sulfide deposits and diffuse hydrothermal fluids will provide insight into the distribution of much larger populations of autotrophic organisms that may be living in the deep subsurface biosphere. This study will take an important step towards quantitative modeling of microbes in surface and subsurface vent environments by combining metabolic rates from laboratory culture studies with detailed field measurements of fluid chemistry constraints on metabolic reactions. The data will be critical to advancing whole-system models of hydrothermal systems. This study will address 3 of the 7 fundamental goals in the RIDGE 2000 Science Plan: 1) determining how biological activity affects vent chemistry, 2) characterizing the forces and linkages that determine the structure and extent of the hydrothermal biosphere, and 3) examination of the nature and space/time extent of the deep subseafloor biosphere. This study will include educational benefits in five areas: 1) graduate student training, 2) undergraduate student training, 3) scientific involvement of underrepresented groups, 4) application of information in courses taught by the investigators, and 5) public education outreach.