Photosynthetic parameters in the Beaufort Sea in relation to the phytoplankton community structure

[摘要] To model phytoplankton primary production from remotely sensed data, a methodto estimate photosynthetic parameters describing the photosynthetic ratesper unit biomass is required. Variability in these parameters must berelated to environmental variables that are measurable remotely. In theArctic, a limited number of measurements of photosynthetic parameters havebeen carried out with the concurrent environmental variables needed. Suchmeasurements and their relationship to environmental variables will berequired to improve the accuracy of remotely sensed estimates ofphytoplankton primary production and our ability to predict future changes.During the MALINA cruise, a large dataset of these parameters was obtained.Together with previously published datasets, we use environmental andtrophic variables to provide functional relationships for these parameters.In particular, we describe several specific aspects: the maximum rate ofphotosynthesis (P_max^chl) normalized to chlorophylldecreases with depth and is higher for communities composed of large cells;the saturation parameter (E_k) decreases with depth but is independent ofthe community structure; and the initial slope of the photosynthesis versusirradiance curve (α^chl) normalized to chlorophyll is independentof depth but is higher for communities composed of larger cells. Thephotosynthetic parameters were not influenced by temperature over the rangeencountered during the cruise (−2 to 8 °C).

[学科分类] 地球化学与岩石