2010-2014 Research Theme Team Workshops

In the initial phase of C-DEBI, the following four themes were the focus of C-DEBI research, providing a conceptual framework for scientific investigation supported by C-DEBI across a broad scientific community: Activity, Extent of Life, Limits to Life, and Evolution and Survival. For each of these themes, Theme Team Leaders regularly brought together experts within and outside of C-DEBI to identify new research directions within each theme. Based on these “think tank” conversations, the Theme Team Leaders developed Requests for Proposals for the initial phase of C-DEBI small grants and fellowship programs.

Research Theme I. Activity in the Deep Subseafloor Biosphere: function & rates of global biogeochemical processes

Theme Team Leaders: Wiebke Ziebis (USC, 2010) & Beth Orcutt (Bigelow, 2012-2014)

Representative ranges of microbial activity in the marine deep biosphere (Orcutt et al. 2013)

What is the global consequence of microbial activity in the marine deep sediment and crustal biospheres? How quickly, or slowly, do processes occur, and what factors regulate these rates? What types of microbial processes are dominant in different environments, and why? What are cell specific rates of activity in the marine deep biosphere? Through targeted support of research aiming to quantify geographic distributions of subseafloor sedimentary respiration, rates and magnitude of microbial crustal alteration, energy sources and carbon flow, C-DEBI enables robust analyses linking subseafloor processes to global scales and biogeochemical cycles.

Download the 2013 Activity Theme Team Workshop Report
Read the 2013 Activity Theme Review [Orcutt et al.] in Frontiers in Microbiology
Read the 2012 Activity Theme Team Workshop Report

Research Theme II. Extent of Life: biomes and the degree of connectivity (biogeography and dispersal)

Theme Team Leader: Andreas Teske (UNC, 2010-2014)

The microbial gauntlet modifies fluxes of deep carbon and gases towards the sediment surface (2013 Extent-Guaymas Workshop)

Over time, the interplay of microbial dispersal and environmental selection creates a distinct biogeography of microbes in the subseafloor. What microbes take seed where and why? What are the most significant physical and chemical controls of these colonization processes? How similar or different are the resulting microbial ecosystems in the ocean crust and in deep sediment from each other and from the overlying deep ocean? By studying multiple sites and subseafloor habitats, C-DEBI research aims to develop a global model for biogeography of microbes below the seafloor.

Download the 2013 joint Extent Theme Team and Guaymas Drilling Proposal Workshop Report
Download the Guaymas Basin IODP Pre-proposal
Download the 2011 Sediment Microbiology DEBI RCN Meeting Report

Research Theme III. Limits to Life: extremes and norms of carbon, energy, nutrient, temperature, pressure, pH

Theme Team Leader: Tom McCollom (UC Boulder, 2010-2014)

Conceptual diagram of the relationship between the metabolic demands of an organism for a potentially limiting factor and the environmental supply of that factor (2011 Limits Workshop)

Numerous studies by C-DEBI participants and others continue to show that microbial life is widespread in the subseafloor. At the same time, however, life is not everywhere, and where it does occur it appears to operate at very slow metabolic rates. How do environmental variables such as temperature, pressure, nutrient availability, fluid flow, pore space, etc. limit the distribution and metabolism of microorganisms in the deep subsurface? What defines the boundary where life can no longer exist in the deep subsurface? C-DEBI promotes investigations into the factors that limit the extent and activity of life in the deep subseafloor, including field, laboratory, and theoretical studies.

Download the 2014 Limits To Life Theme Team Workshop Report
Download the 2011 Limits To Life Theme Team Workshop Report

Research Theme IV. Evolution and Survival: adaptation, enrichment, and repair

Theme Team Leaders: Bill Nelson (USC, 2010-2013) & Julie Huber (2013-2014)

Overview of the phylogenetic relationship of 16S rRNA genes sequences for (A) Bacteria and (B) Archaea (Biddle et al. 2012)

Reproduction, change, and selection are necessary elements of any evolutionary trajectory, but we know very little about evolution and adaptation in subseafloor habitats. What are the metabolic drivers that might lead to selection in the subseafloor? In an environment where biomass turnover may occur on a timescale of hundreds to thousands of years, can you actually detect evolutionary changes? How does lateral gene transfer impact evolutionary trajectories in the subseafloor? Through a combination of field and laboratory based measurements, C-DEBI research aims to examine these key questions about microbial evolutionary processes in the subseafloor.

Download the 2013 Evolution Theme Team Workshop Report
Read the 2012 Evolution Theme Review [Biddle et al.] in Frontiers in Microbiology
Download the 2011 Evolution Theme Team Workshop Report