Table of Contents

• Dataset Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

One decibar-averaged CTD profile data from cruise CB934

The project description is from the NSF award abstract.

The vast majority of sinking organic carbon formed within the surface layer of the ocean is degraded in transit through the water column, and heterotrophic bacteria on sinking particles are important agents of this process. Recent work suggests that these bacteria have the ability to regulate organic carbon degrading metabolisms by communicating with one another via quorum sensing (QS). QS is a process where bacteria use cell-cell signaling to gauge the density of related cells in their environment for the purpose of coordinating metabolic responses among these related cells.

In this study, researchers at the Woods Hole Oceanography Institution and the Marine Biological Laboratory will test the hypothesis that AHL-based QS systems are active in sinking marine particles by trapping sinking particles, and analyzing them for cell-cell signaling molecules that are diagnostic for active QS. Sinking marine particles contain abundant Proteobacteria. This group of bacteria utilizes a class of QS molecules called acylated homoserine lactones (AHL) for which the team has previously developed new pre-concentration and mass spectrometry methods for analyzing AHLs in sinking particles.

Additionally, the team will also test the hypothesis that that genes regulated by AHL-based QS in sinking particles encode enzymes for organic matter degradation by constructing libraries of genomic DNA from sinking particles and screening these libraries for AHL production. This should enable sections of genomic DNA that contain AHL-regulated genes to be singled out and analyzed further for genes encoding hydrolytic enzymes without relying on sequence database searches. Finally, they will apply a "functional gene expression" strategy to definitively constrain whether hydrolytic enzymes are indeed the products of these AHL-regulated genes. In previous work, the research team found that some marine bacteria also secrete enzymes to degrade AHLs; consequently, they will will examine whether this is occurring on sinking particles using both functional gene expression assays and incubation-based experiments.

This study of quorum sensing in sinking particles has the potential to reveal previously uncharacterized linkages between bacterial community composition and particle flux attenuation. The primary justification for the proposed study is that quorum sensing is one such connection. QS has been well-characterized in the biomedical literature, and, as such, is ripe for exploration in marine environments.

The Ocean Carbon and Biogeochemistry (OCB) program focuses on the ocean's role as a component of the global Earth system, bringing together research in geochemistry, ocean physics, and ecology that inform on and advance our understanding of ocean biogeochemistry. The overall program goals are to promote, plan, and coordinate collaborative, multidisciplinary research opportunities within the U.S. research community and with international partners. Important OCB-related activities currently include: the Ocean Carbon and Climate Change (OCCC) and the North American Carbon Program (NACP); U.S. contributions to IMBER, SOLAS, CARBOOCEAN; and numerous U.S. single-investigator and medium-size research projects funded by U.S. federal agencies including NASA, NOAA, and NSF.

The scientific mission of OCB is to study the evolving role of the ocean in the global carbon cycle, in the face of environmental variability and change through studies of marine biogeochemical cycles and associated ecosystems.

The overarching OCB science themes include improved understanding and prediction of: 1) oceanic uptake and release of atmospheric CO2 and other greenhouse gases and 2) environmental sensitivities of biogeochemical cycles, marine ecosystems, and interactions between the two.

The OCB Research Priorities (updated January 2012) include: ocean acidification; terrestrial/coastal carbon fluxes and exchanges; climate sensitivities of and change in ecosystem structure and associated impacts on biogeochemical cycles; mesopelagic ecological and biogeochemical interactions; benthic-pelagic feedbacks on biogeochemical cycles; ocean carbon uptake and storage; and expanding low-oxygen conditions in the coastal and open oceans.