Aquatic Sciences Meeting, Albuquerque 2001

SS43 Biogeochemical Processes in Stromatolites: A 3 b.y.old ecosystem (Spatial and Temporal Connections)

Date: Monday, February 12, 2001, Time: 3:00:00 PM

Location: Cimarron

Des Marais, D, J, NASA Astrobiology Institute, Ames Research Center, Moffett Field, CA 94035, USA, ddesmarais@mail.arc.nasa.gov

Discipulo, M, , NASA Astrobiology Institute, Ames Research Center, Moffett Field, CA 94035, USA,

CARBON AND OXYGEN BUDGETS OF SUBTIDAL AND INTERTIDAL CYANOBACTERIAL MATS

Intertidal cyanobacterial mats (Lyngbya-dominated) are contrasted with mats (Microcoleus-dominated) that grow in subtidal (0.7m water depth) hypersaline (90-110 permil) environments. In benthic chamber experiments conducted in Oct., 1999, Lyngbya mats exhibited greater net uptake of dissolved inorganic carbon (DIC) from overlying water during the daylight period than Microcoleus mats (e.g., 200 vs 120 mmol C/m at 26 deg C, respectively). Net DIC release at night was similar for both mats (~80 mmol C/m). Daytime net O2 release by Lyngbya mats exceeded that by Microcoleus mats (150 vs 100 mmol O2/m), and O2 uptake at night was comparable for both mats (60-80 mmol O2/m). Nonphotosynthetic populations are more prominent within the subtidal versus intertidal mats, and accordingly exhibited greater internal O2 uptake and DIC production during the day. Over 24 hours, Lyngbya-dominated mats exhibited greater net uptake of DIC than subtidal Microcoleus mats, consistent with these intertidal mats being 'pioneer'; communities that constantly recover from periodic physical disruption in energetic environments. The Microcoleus-dominated mats achieve steady-state mat thicknesses by balancing primary production against diagenetic decomposition of cellular and extracellular organic constituents.

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Aquatic Sciences Meeting, Albuquerque 2001

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