Aquatic Sciences Meeting, Albuquerque 2001

CS41 Phytoplankton: Nutrient Dynamics and Physiology

Date: Friday, February 16, 2001, Time: 11:45:00 AM

Location: Galisteo

Laney, S, R, Darling Marine Center, University of Maine, Walpole Maine, USA, sam@hawkeye.dmc.maine.edu

Letelier, R, M, COAS Oregon State University, Corvallis Oregon, USA, letelier@oce.orst.edu

Abbott, M, A, COAS Oregon State University, Corvallis Oregon, USA, mark@oce.orst.edu

ELECTRON TRANSPORT MODELS OF PHOTOSYNTHESIS: HOW IMPORTANT IS REACTION CENTER CONNECTIVITY?

Indices of photosynthetic rate can be calculated using Fast Repetition Rate Fluorometers (FRRFs) or similar methods by modeling the kinetics of light-driven electron flow in Photosystem II (PSII). Analysis of FRRF measurements can retrieve a parameter describing the energetic connectivity between PSII reaction centers, yet the effect of this connectivity on total electron flow has not been closely examined. Numerical simulations exhibited connectivity-enhanced PSII electron flow when the fraction of nonfunctional reaction centers was increased or when the PSII population was densely packed. RCII connectivity was experimentally determined in continuous cultures of Thalassiosira weissflogii (Bacillariophyceae) using a commercial FRRF and an analysis program employing robust estimation algorithms. Substantial variability in connectivity was observed in the culture phytoplankton over diel and longer time scales and connectivity showed different characteristics as a function of nitrate availability. Estimates of connectivity and functional cross section differed between the custom and the commerically supplied FRRF software. Although not easily retrieved from raw FRRF measurements, connectivity appears to be an important parameter to more accurately model light driven electron flow rates.

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Aquatic Sciences Meeting, Albuquerque 2001

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