DeGrandpre, M. D.. University of Montana, mdegrand@selway.umt.edu
Olbu, G. D.. University of Montana, golbu@uswest.net
Wirick, C. D.. Brookhaven National Laboratory, wirick@bnl.gov

 
NET COMMUNITY PRODUCTION IN COASTAL WATERS: ESTIMATES FROM MOORING-BASED MEASUREMENTS OF PCO2 AND O2
 
Numerous methods exist for estimating rates of primary production in natural waters. Although many of these techniques have been adapted to perform in situ incubations of enclosed water volumes, few are amenable to long-term deployment on moorings. Moorable systems would provide long-term, high temporal resolution estimates of production rates which would greatly improve our ability to quantify and understand the controls of primary production. In recent years moorable CO2 and O2 gas sensors have become available - these sensors record the rates of change of CO2 and O2 inventories in the mixed-layer. The rates, after correction for physical contributions, represent the rate of net community production (the difference between net primary production and net community respiration). Our past field work has utilized our Submersible Autonomous Moored Instrument for CO2 (SAMI-CO2), which records the partial pressure of CO2 (pCO2), along with commercial pulsed polarographic O2 electrodes. Total CO2 is determined by calculation from the salinity-derived alkalinity and measured pCO2. Rates of change of mixed-layer CO2 and O2 inventories are intercompared by using a photosynthetic quotient of 1.4. Results using this approach are discussed for instrument deployments in California coastal and Middle Atlantic Bight waters. The mooring-based estimates of net community production are also compared to shipboard measurements and a discussion of future directions is presented.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: CS55TH0585S