Carbon and Oxygen Budgets of Hypersaline Cyanobacterial Mats: Effects of Tidal Cycle and TemperatureThe hierarchical organization of microbial ecosystems determines the rates of processes that shape Earth#s environment, define the stage upon which major evolutionary events occurred, and create biosignatures in sediments and atmospheres. In cyanobacterial mats, oxygenic photosynthesis provides energy, organic substrates and oxygen to the ecosystem. Incident light changes with depth in the mat, both in intensity and spectral composition, and counteracting gradients of oxygen and sulfide shape the chemical microenvironment. A combination of benefits and hazards of light, oxygen and sulfide promotes the allocation of the various essential mat processes between light and dark periods and to various depths in the mat. Microbiota produce hydrogen, small organic acids, and nitrogen and sulfur species. Such compounds fuel a flow of energy and electrons in these ecosystems and thus shape interactions between groups of microorganisms. Coordinated observations of population distribution, abundance, and activity for an entire community are making fundamental questions in ecology accessible. These questions address those factors that sustain the remarkable diversity of microorganisms that are now being revealed by molecular techniques. These questions also target the processes that shape the various kinds of biosignatures that we will seek, both in ancient rocks from Earth and Mars, and in atmospheres of distant planets beyond our Solar System.
Document ID
20030023599
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
DesMarais, David J. (NASA Ames Research Center Moffett Field, CA, United States)
Bebout, Brad M. (NASA Ames Research Center Moffett Field, CA, United States)
Carpenter, Steven (Orbital Corp. Moffett Field, CA, United States)
Discipulo, Mykell (Search for Extraterrestrial Intelligence Inst. Mountain View, CA, United States)
Turk, Kendra (California Univ. Santa Cruz, CA, United States)