Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean


Poulton, A.J., Holligan, P.M., Hickman, A., Kim, Y.N., Adey, T.R., Stinchcombe, M.C., Holeton, C., Root, S. and Woodward, E.M.S. (2006) Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean. Deep-Sea Research II, 53, (14-16), 1593-1610. (doi:10.1016/j.dsr2.2006.05.007).

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Description/Abstract

We have made daily measurements of phytoplankton pigments, size-fractionated (<2 and >2-μm) carbon fixation and chlorophyll-a concentration during four Atlantic Meridional Transect (AMT) cruises in 2003–04. Surface rates of carbon fixation ranged from <0.2-mmol C m−3 d−1 in the subtropical gyres to 0.2–0.5-mmol C m−3 d−1 in the tropical equatorial Atlantic. Significant intercruise variability was restricted to the subtropical gyres, with higher chlorophyll-a concentrations and carbon fixation in the subsurface chlorophyll maximum during spring in either hemisphere. In surface waters, although picoplankton (<2-μm) represented the dominant fraction in terms of both carbon fixation (50–70%) and chlorophyll-a (80–90%), nanoplankton (>2-μm) contributions to total carbon fixation (30–50%) were higher than to total chlorophyll-a (10–20%). However, in the subsurface chlorophyll maximum picoplankton dominated both carbon fixation (70–90%) and chlorophyll-a (70–90%). Thus, in surface waters chlorophyll-normalised carbon fixation was 2–3 times higher for nanoplankton and differences in picoplankton and nanoplankton carbon to chlorophyll-a ratios may lead to either higher or similar growth rates. These low chlorophyll-normalised carbon fixation rates for picoplankton may also reflect losses of fixed carbon (cell leakage or respiration), decreases in photosynthetic efficiency, grazing losses during the incubations, or some combination of all these. Comparison of nitrate concentrations in the subsurface chlorophyll maximum with estimates of those required to support the observed rates of carbon fixation (assuming Redfield stoichiometry) indicate that primary production in the chlorophyll maximum may be light rather than nutrient limited.

Item Type: Article
ISSNs: 0967-0645 (print)
Related URLs:
Keywords: phytoplankton; carbon fixation; picoplankton; nanoplankton; chlorophyll-a; Atlantic Meridional Transect
Subjects: G Geography. Anthropology. Recreation > GC Oceanography
Q Science > QH Natural history > QH301 Biology
Divisions: University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
University Structure - Pre August 2011 > National Oceanography Centre (NERC)
ePrint ID: 43985
Date Deposited: 06 Feb 2007
Last Modified: 27 Mar 2014 18:28
URI: http://eprints.soton.ac.uk/id/eprint/43985

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