What is MICROBE Main Page: Research: The MICROBE Project
The MICROBE (Microcosm Investigation of Carbonate Reef/Ocean microbial Biogeochemistry & Ecology) Project
What is MICROBE MICROBE started as a project funded by the National Science Foundation (NSF) Research in Biogeosciences Program between 2003 and 2005. Its first phase aimed at developing an experimental microcosm method suitable as a platform for answering questions pertaining to the microbial biogeochemistry of permeable sediments, and specifically carbonate coral reef sediments. Most of the development took place at the Department of Oceanography of the School of Ocean and Earth Science and Technology (SOEST) of the University of Hawai`i at Manoa. In 2005, the microcosm system was temporarily based at Kewalo Marine Laboratory (KML) of the Pacific Biomedical Research Center (PBRC) of the University of Hawai`i at Manoa. Various longer-time-scale measurements were conducted during this period, as well as the testing of added components. With the first phase complete, the next phase aims at answering specific questions about permeable sediments: their microbial communities, ecosystem function and biogeochemical cycling from local to planetary scales. For more details, see our presentations and publications below.
The MICROBE microcosm reproduces the hydraulic and geochemical character of permeable marine sediments. This is achieved by producing enhanced overlying-pore water exchange and redox gradients extending over several decimeters, while it also allows the non-destructive sampling of pore water for geochemical and biological analyses. The microcosm consists of a biogeochemically active sediment column (marked A in this schematic diagram of the microcosm) connected in parallel to a silica sand column (marked B). Overlying water is pumped between the two columns by Pump A to generate hydrostatic head changes similar to those induced by waves and tides over natural reef sediments. Pump B circulates water through the microcosm with the incoming water coming from a reservoir, where it can be manipulated to desirable conditions.
We have demonstrated with dye tracer experiments (Exp. 1, 5 and 6) that the oscillatory flow induced by changes in head enhances the transport of solutes by several times to orders of magnitude over molecular diffusion. In experiments with carbonate reef sediments (Exp. 2-4), we qualitatively reproduced the oxygen profiles observed in natural reef settings, and demonstrated non-destructive sampling of the microcosm pore waters for solutes and microbes. A detailed technical description of the microcosm and results of proof-of concept experiments are included in our presentations and publications (below). We are convinced that our microcosm system can be succesfully used to experimentally manipulate sediment columns to investigate the impact of local and global change on the biogeochemistry of permeable marine sediments.
Hannides, A.K., Gaidos, E.J., and Sansone, F.J. (2005) A Microcosm at Work: Preliminary Experiments from the MICROBE Project. ASLO 2005 Aquatic Sciences Meeting, Salt Lake City, Utah, USA, February 20th-25th, 2005. [ abstract ] [ talk pdf ]
Hannides, A.K., Gaidos, E.J., and Sansone, F.J. (2003) The MICROBE (Microcosm Investigation of Carbonate Reef/Ocean Microbial Biogeochemistry & Ecology) Project, Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract B12B-0779, December 8th-12th, 2003. [ abstract ] [ poster pdf ]
Hannides, A.K., Gaidos, E.J., and F.J. Sansone (submitted) A microcosm system for the experimental study of permeable sediment biogeochemistry. Limnology and Oceanography Methods.
Angelos K. Hannides, Department of Oceanography,
Last modified: February 2006
