Woods Hole Oceanographic Institution
2019-2020 Distinguished Lecturer

Life at the edge of what is possible: Microbial biosignatures in the lower oceanic crust

The lower oceanic crust represents one of the last frontiers for biological exploration on Earth. Even if life exists in only a fraction of the habitable volume where temperatures permit and fluid flow can deliver carbon and energy sources, an active lower oceanic crust biosphere would have implications for deep carbon budgets and may yield insights into microbiota that may have existed on early Earth. For subsurface microbiota, the major challenge is obtaining sufficient carbon and energy. Subsurface microbiota and the biogeochemical cycles they mediate are likely linked to deep ocean processes through faulting and subsurface fluid flow. IODP Expedition 360 to the Atlantis Bank Oceanic Core Complex on the SW Indian Ridge, Indian Ocean, presented a unique opportunity to explore the microbiology of the lower oceanic crust which is exposed at the seafloor in ~700m of water, providing unique drilling access to this otherwise largely inaccessible realm. Dr. Edgcomb uses isolation of microorganisms and culture-based studies coupled with molecular approaches and microscopy to reveal the identities, activities, and interactions of subsurface microbial communities.  She has a special interest in marine microbial eukaryotes, and in the role of Fungi in the deep biosphere.

Dr.  Edgcomb will present research from the Indian Ocean lower oceanic crust (IODP Expedition 360, Atlantis Bank) that provides evidence for living/viable microbiota in this challenging habitat from a range of analyses, and insights into metabolic strategies for coping with conditions in this challenging realm, including temporal and spatial heterogeneity in the supply of sources of nutrients and energy. She will touch on comparisons with studies of the marine sedimentary deep biosphere.

Dr. Edgcomb is an Associate Scientist in the Department of Geology and Geophysics at Woods Hole Oceanographic Institution. Her research focuses on the microbiology of oxygen-depleted and anoxic water columns and sediments, and the deep subsurface biosphere.  She received her Ph.D. in Biology from the University of Delaware, and undergraduate degree from University of Virginia. Ginny participated as a shipboard scientist on IODP Expedition 360 to Atlantis Bank, Indian Ocean, and is scheduled to sail on Expedition 385 to Guaymas Basin, Gulf of California, in 2019.

TBD – Montana Technological University; Butte, MT
TBD – University of Utah; Salt Lake City, UT
TBD – Northern Virginia Community College; Annandale, VA
TBD – University of South Carolina, Columbia; Columbia, SC
TBD – Lafayette College; Easton, PA
TBD – University of Texas, Arlington; Arlington, TX
TBD – Southwest Oregon Community College; Coos Bay, OR