The oceanic crust, located often below a thick layer of sediment, is one of Earth’s most remote habitats. The permeable basement rock hosts a dynamic aquifer, where water isolated from the sea above can circulate. Microorganisms in this crustal biosphere are deprived of sunlight and the planet’s typical food web. Instead, the organisms depend on the minerals and nutrients of the subseafloor aquifer. There is much to learn from these organisms, including their contributions to global biogeochemical cycles and their strategies for surviving in their nutrient and energy-limited habitat. For 27 years, the international ocean drilling community has studied this environment—and the microorganisms living within—using subseafloor borehole observatories. Because the lifestyles of these microorganisms are different from those at the surface, cultivation has been mostly unsuccessful. Thus, much of what we know about these elusive organisms results from genomic analyses. This presentation is an introduction to the borehole observatories of the Juan de Fuca Ridge Flank and our genomic understanding of the unique but abundant microorganisms of the marine crust.
Ocean Discovery Lecture Series
For more than 20 years, the Ocean Discovery Lecture Series (formerly the Distinguished Lecturer Series) has brought the remarkable scientific results and discoveries of the International Ocean Discovery Program and its predecessor programs to academic research institutions, museums, and aquaria. Since 1991, more than 1,000 presentations to diverse audiences have been made through the Lecture Series.