Photoadaptive response during the development of a coastal Antarctic diatom bloom and relationship to water column stability

Moline, Mark A.

Limnol. Oceanogr., 43(1), 1998, 146-153 | DOI: 10.4319/lo.1998.43.1.0146

ABSTRACT: The raio of the xanthophylll pigments diadinoxanthin and diatoxanthin to chlorophyll a [(DD+DT}:Chl a] was used as a photoadaptive index during the development of a large Antarctic diatom bloom. This index was found to track fluctuations in the incident solar irradiance and the in situ light field over a 3 order magnitude change in the water column biomass. Depth profiles of the (DD+DT}:Chl a ratio showed that the upper mixed layer, assessed by physical data, was in fact stable over the course of the month. Diel experiments conducted over the same period showed a delayed (5-8 h) response of the DD+DT pool to the instantaneous Qpar (400-700 nm) irradiance. These time series results illustrate the potential use of xanthophyll pigmnents in assessing phytoplankton light histories and the degree of water column stability.

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