MEPS 543:73-87 (2016)  -  DOI: https://doi.org/10.3354/meps11580

Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay)

Eva Álvarez1,*, Xosé Anxelu G. Morán1,2, Ángel López-Urrutia1, Enrique Nogueira

1Instituto Español de Oceanografía, Centro Oceanográfico de Gijón/Xixón, Asturias, Spain
2Present address: Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
*Corresponding author:

ABSTRACT: Shelf waters of the Cantabrian Sea (southern Bay of Biscay) are productive ecosystems with a marked seasonality. We present the results from 1 yr of monthly monitoring of the phytoplankton community together with an intensive sampling carried out in 2 contrasting scenarios during the summer and autumn in a mid-shelf area. Stratification was apparent on the shelf in summer, while the water column was comparatively well mixed in autumn. The size structure of the photoautotrophic community, from pico- to micro-phytoplankton, was tightly coupled with the meteo-climatic and hydrographical conditions. Over the short term, variations in the size structure and chlorophyll content of phytoplankton cells were related to changes in the physico-chemical environment, through changes in the availability of nutrients and light. Uncoupling between the dynamics of carbon biomass and chlorophyll resulted in chlorophyll to carbon ratios dependent on body size. The slope of the size dependence of chlorophyll content increased with increasing irradiance, reflecting different photoacclimation plasticity from pico- to micro-phytoplankton. The results have important implications for the productivity and the fate of biogenic carbon in this region, since the size dependence of photosynthetic rates is directly related to the size scaling of chlorophyll content.


KEY WORDS: Phytoplankton · Hydrography · Chlorophyll:carbon ratio · Size spectra · Size scaling · Continental shelf · Cantabrian Sea


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Cite this article as: Álvarez E, Morán XAG, López-Urrutia Á, Nogueira E (2016) Size-dependent photoacclimation of the phytoplankton community in temperate shelf waters (southern Bay of Biscay). Mar Ecol Prog Ser 543:73-87. https://doi.org/10.3354/meps11580

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