Bergmann, T. I. IMCS, Rutgers University, bergmann@arctic.rutgers.edu
Schofield, O. IMCS, Rutgers University, oscar@ahab.rutgers.edu
Kirkpatrick, G. Mote Marine Laboratory, gkirkpat@mote.org
Millie, D. Southern Regional Research Center, Agricultural Research Service - USDA, dmillie@nola.srrc.usda.gov
Paerl, H. Institute of Marine Sciences, University of North Carolina at Chapel Hill, hpaerl@email.unc.edu

 
IMPACT OF LIGHT AND NUTRIENTS ON THE MAXIMUM QUANTUM YIELD OF PHOTOSYSTEM II FOR NATURAL PHYTOPLANKTON POPULATIONS FROM THE NEUSE RIVER, NC
 
A mesocosm experiment was conducted to determine the synergistic interactions of light and nutrients on the maximum quantum yield of stable charge separation at photosystem II (Fv/Fm) for natural phytoplankton communitites collected from the Neuse River Estuary. The mesocosm treatments included control, + ammonium, + nitrate, + nitrate and ammonium, and + nitrate, ammonium, and phosphorus (3-4 replicates per treatment) for both static and aerated tanks. A full suite of pigmentation, absorption, total carbon fixation, and Fv/Fm data were collected every 2-3 hours over the 4 day experiment. The addition of nitrogen resulted in close to a 40% increase in Fv/Fm values within 24 hours, but no significant differences were observed between the different nitrogen treatments. This supports previous work suggesting that the Neuse river is nitrogen limited. Diurnal trends in Fv/Fm exhibited an inverse relationship to instantaneous light. Mixed mesocosm treatments rapidly recovered when light levels declined. The decreases in Fv/Fm were largely due to midday decreases in the maximum fluorescence level suggesting the large diurnal variability reflected physiological responses to bright light. Many of the responses observed in Fv/Fm mirrored bulk productivity measurements.
 
Day: Thursday, Feb. 4
Time: 04:45 - 05:00pm
Location: Hilton of Santa Fe
 
Code: SS51TH0445E