Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4538810 | Deep Sea Research Part II: Topical Studies in Oceanography | 2005 | 31 Pages |
Abstract
The effective quantum yield for carbon assimilation, Ïc (mol CÂ Einsteinâ1), quantifies the efficiency by which phytoplankton use absorbed light energy to photochemically fix and store carbon. A five-year time series from the Sargasso Sea shows a high degree of variability in estimated values of Ïc. A significant seasonal cycle is found as Ïc values are reduced in summer. However, this seasonal cycle explains only a small fraction of the total variance in Ïc, and very few environmental parameters correlate with Ïc. Significant correlation is observed between Ïc and the flux of photosynthetically active radiation, QPAR, and between Ïc and the rate at which phytoplankton absorb quanta, AQPAR. Near-surface Ïc values also are correlated with concentrations of the photoprotectant pigment zeaxanthin, where Ïc values are depressed when zeaxanthin concentrations are elevated. Four previously published Ïc models are assessed using these data. The predictive skill for each of these Ïc models indicates that they behave as good data interpolators, but poor predictors of Ïc variability. The prognostic capability of these models does not improve when seasonal mean parameters are applied. The present results demonstrate the difficulties in modeling primary production, as we have yet to develop a predictive understanding of the important photophysiological, ecological and methodological processes regulating primary production.
Related Topics
Physical Sciences and Engineering
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Authors
Jens C Sorensen, David A Siegel,