HR: 13:55h
AN: B23G-02    [Abstracts]
TI: Spatial and Temporal Variability in Microbial Communities from Pre- and Post-Eruption Microbial Mats Collected from Loihi Seamount, Hawaii: An Update
AU: * Moyer, C L
EM: cmoyer@hydro.biol.wwu.edu
AF: Western Washington University, Biology Department MS# 9160, Bellingham, WA 98225, United States
AU: Davis, R E
EM: davisr@ebs.ogi.edu
AF: Western Washington University, Biology Department MS# 9160, Bellingham, WA 98225, United States
AU: Curtis, A C
EM: andrea@estrus.com
AF: Western Washington University, Biology Department MS# 9160, Bellingham, WA 98225, United States
AU: Rassa, A C
EM: cyrus64@gmail.com
AF: Western Washington University, Biology Department MS# 9160, Bellingham, WA 98225, United States
AB: Loihi Seamount is an active submarine volcano that marks the southernmost extent of the Hawaiian hotspot. Loihi rises over 3000 meters from the seafloor and summits nearly 1000 meters below sea level. Hydrothermal activity was discovered at Loihi in 1987, yielding diffuse vent effluent (Tmax 37°C) with associated high CO₂ and Fe(II) concentrations and luxuriant microbial mats located near the summit of the volcano. Loihi erupted most recently in 1996 forming a new 300 meter deep caldera (Pele's Pit) with hydrothermal venting up to 200°C. Pele's Pit has cooled and now contains multiple hydrothermal vents with hydrothermal fluids ranging from 8-58°C with concentrations of Fe(II) remaining between 50 and 750 μM. Community fingerprints from over 75 microbial mat samples have now been collected from Loihi Seamount from 1993 to 2006, with temperatures ranging from ambient (~4°C) up to nearly ~200°C. These samples were analyzed using Pearson product-moment coupled with UPGMA cluster analysis of terminal- restriction fragment length polymorphisms (T-RFLP) coupled with traditional clone library and sequence analysis to identify the primary populations within each community. These mat samples form two distinct community clusters (Loihi Cluster Group 1 and Group 2) representing a combined 90% of all mat samples collected. Loihi Cluster Group 1 is by far the largest group (n = 45) and contains the most mat samples collected over time. Group 1 is dominated by phylotypes closely related to the recently described zeta- Proteobacteria that includes the type strain Mariprofundus ferrooxydans, an obligately lithotrophic, Fe-oxidizing bacterium. Loihi Cluster Group 2 is comprised of only post-eruption communities (n = 18) that generally contain greater diversity (in terms of richness) than Group 1 communities. Group 2 communities are primarily dominated by a unique array of phylotypes belonging to the Nitrospira division and by the class epsilon- Proteobacteria, including many putative sulphur-oxidizing bacteria. Interestingly, we have recently witnessed a shift away from the Group 2 communities back to the Group 1 communities. Only 2 of 11 microbial mat samples collected in 2004 exhibited the Group 2 community structure. All 10 of the mat samples collected in 2006 from multiple locations exhibited the Group 1 community structure, indicating a reduced overall diversity within Pele's Pit and a return to the microbial mats being dominated by Fe-oxidizing bacteria.
UR: http://fire.biol.wwu.edu/cmoyer/research.html
DE: 4803 Analytical chemistry
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
DE: 4832 Hydrothermal systems (0450, 1034, 3017, 3616, 8135, 8424)
DE: 4840 Microbiology and microbial ecology (0465)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting