The deep biosphere of the ocean crust: biomass, diversity, activity and biogeochemical cycles

Until recently it was generally believed that microbes could only thrive in the Earths surface regions. During the last years, observation of microbes in deep groundwater, oil wells and deep-sea hydrothermal vents, sub-seafloor sediments and oceanic igneo us crust has given increasing evidence for the existence of a deep and widespread subsurface biosphere. In this project we will study the deep biosphere of the ocean floor by sampling the ocean crust, using a small submersible drill rig. We will develop in situ growth experiments that will be deployed in the drill holes and later recovered from the ocean fl oor to give vital new information on the functioning of the deep biosphere ecosystems and the interactions between the deep biosphere, geosphere and hydrosphere. In cooperation with international network partners, these experimental packages will subsequently be improved and modified so that they can be developed in deep holes drilled by the Integrated Ocean Drilling Program (IODP) and function as deep biosphere o bservatories.