Journal of
Oceanography and Marine Science

  • Abbreviation: J. Oceanogr. Mar. Sci.
  • Language: English
  • ISSN: 2141-2294
  • DOI: 10.5897/JOMS
  • Start Year: 2010
  • Published Articles: 60

Full Length Research Paper

On the Nutrient distribution and phytoplankton biomass in the Gulf of Guinea equatorial band as inferred from In-situ measurements

Nubi O. A.
  • Nubi O. A.
  • Nigerian Institute for Oceanography and Marine Research, Lagos, Nigeria.
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Bourlès B.
  • Bourlès B.
  • Institut de Recherche pour le Développement (IRD) de Brest, Plouzané, France.
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Edokpayi C. A.
  • Edokpayi C. A.
  • Marine Sciences Department, University of Lagos, Nigeria.
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Hounkonnou M. N.
  • Hounkonnou M. N.
  • International Chair in Mathematical Physics and Applications (ICMPA), University of Abomey-Calavi, Republic of Benin.
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  •  Received: 22 January 2016
  •  Accepted: 28 June 2016
  •  Published: 31 July 2016

Abstract

Oceanographic in situ data collected in the Gulf of Guinea during six cruises carried out between 2005 and 2007 were analysed to study the influence of equatorial upwelling on the productivity of the region. At 10°W, observations during boreal summer and autumn cruises captured seasonal upwelling influences. In response to the shoaling pycnocline in June 2005, higher concentrations of nitrate and chlorophyll fluorescence were recorded at the ocean surface in June than in September. Our findings challenge the paradigm that westward advection from the nutrient-rich African coast is responsible for equatorial enrichment in the Gulf of Guinea. Vertical sections of the parameters under study in the summer of 2005 showed no westward advection from 3°E to 10°W within the equatorial band. This emphasizes the important role of vertical processes in equatorial enrichment at 10°W. An additional aspect of our study provides evidence of the impact on nutrient and chlorophyll distribution of off-equatorial westward recirculation of equatorial undercurrent waters (observed between 2°and 3°S).

 

Key words: Advection, equatorial undercurrent, equatorial upwelling, Gulf of Guinea, nutrients, phytoplankton biomass.