N-191. Endolithic Microbial Communities of Juan de Fuca Ridge Hydrothermal Vent Chimneys

E. E. Cordes¹, G. Wheat², D. Kelley³, P. Girguis¹;
¹Harvard Univ., Cambridge, MA, ²Monterey Bay Aquarium Res. Inst., Moss Landing, CA, ³Univ. of Washington, Seattle, WA.

Hydrothermal vents represent some of the most extreme environments on earth where hydrothermal fluids, often in excess of 300°C, rapidly mix with cold, deep-sea seawater. Although this mixing zone can be quite dynamic, more stable gradients of temperature and fluid chemistry are established within the porous walls of some chimney structures. To investigate the microbial ecology of these structures at the Endeavour segment of the Juan de Fuca Ridge system, a series of titanium sleeves packed with sterile substrates and lined with temperature and small-volume water samplers were incubated in chimney walls for days to over a year. Clone libraries include a number of sequences from poorly-known microbial groups, some of which (Epsilon-proteobacteria and Crenarchaeota phylotypes) appear to be early colonizers of hydrothermal environments. Quantitative-PCR and FISH data indicate changes in abundance across steep spatial gradients in geochemistry and temperature, as well as successional changes in the microbial communities inhabiting the time series of experimental deployments.