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Underwater light field and phytoplankton distribution during a daily cycle in the Ría of Vigo (NW Spain)
F.L. Figueroa, F. Jiménez-Gómez, M.L. Villarino, J. Rodríguez and F.G. Figueiras

Changes in the air and underwater light fields were analyzed through a daily cycle in an estuarine system (Ria de Vigo, NW Spain). Underwater light quality changed with depth throughout the day, and the variation was related to phytoplankton distribution in the water column and to the angular distribution of the incident light. The contribution of light attenuation at different wavelengths (blue, green, yellow-orange, red and far-red) to changes in the attenuation coefficient of the total radiation (between 350 and 800 nm) was determined. The attenuation of blue (B) and red (R) light was greater than green and yellow-orange, as corresponds to waters with a high content of particles (tripton and phytoplankton). The highest values of vertical attenuation coefficient at B and R bands corresponded to maxima of phytoplankton biomass. The vertical profiles of fluorescence correlated with that of the spectral vertical attenuation coefficient.

Keywords: Daily cycle, flow cytometry, estuarine system, phytoplankton distribution, vertical attenuation coefficient, spectral photon flux, underwater light field.
Contents of this volume Sci. Mar. 58(1-2) : 119-130 Back PDF
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