Productivity in upwelling areas deduced from hydrographic and chemical fields1

Minas, H. J.; Minas, M.; Packard, Theodore T.

doi:10.4319/lo.1986.31.6.1182

Cited by 177 publications

(86 citation statements)

References 42 publications

(39 reference statements)

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“…However, these areas, first designated as high nutrient, low chlorophyll (HNLC) areas by Minas et al (1986), although exhibiting unused NO 3 , often were even lower in Si(OH) 4 , suggesting these areas were Si(OH) 4 limited for diatoms. Some of these areas were re-designated as low silicate-HNLC (Dugdale and Wilkerson, 1998) and included the Southern Ocean in the region of the polar front, the region between the Peru/Ecuador coast and the Galapagos Islands, and the Eastern Equatorial Pacific (EEP) (Dugdale et al, 1995).…”

Section: Low Si(oh) 4 -High No 3 Low Chlorophyll Areasmentioning

confidence: 99%

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Dugdale

Wilkerson

2001

Sci. Mar.

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INTRODUCTIONThe biogeochemistry of silicon (Si) is the focus of considerable contemporary attention by geochemists, paleoceanographers and paleoclimatologists. Biologists are showing revived interest in the Si cycle in relation to diatom productivity as it's very strong role in marine productivity (e.g. Smetacek, 1999) and effect on ocean-atmosphere processes becomes apparent, following a period in which the focus was almost exclusively on smaller and smaller planktonic organisms. The objective of this communication is to review the role of biological processes in the formation of the ocean Si environment first at the broad scale and then in more detail in two special settings, the equatorial Pacific and the Southern Ocean. In doing so, we will follow the evolution of a set of nitrogen (N) based models, that conclude with inclusion of Si and it's impact on global carbon cycles and paleoclimatology. We will examine the differences between the oceanic Si and N cycle, the existence of areas of unusually low silicate relative to nitrate concentrations and how we think they are formed. The concept of the Pacific equatorial upwelling area as a Si limited chemostatlike system and the model complexity necessary to describe its functioning will be presented. SUMMARY: Diatoms with their fast growth rates and obligate requirement for Si have a unique relationship to the oceanic Si cycle with the potential for controlling the nutrient and CO 2 environment of large important areas of the ocean. The new production of diatoms based on both new nitrogen and Si sources is described using a Si-pump based upon the differential regeneration of the two elements. This approach, applied to the eastern equatorial Pacific, showed diatoms to respond as in a Si-limited chemostat, to the low source Si(OH) 4 in the Equatorial UnderCurrent. Increased Si(OH) 4 results in increased diatom productivity, suppression of non-diatom populations and decreased surface pCO 2 . The deficiency in source concentrations of Si(OH) 4 results from low Si(OH) 4 :NO 3 water originating in the vicinity of the Antarctic Polar Front, a consequence of the extraordinary trapping of Si by the Southern Ocean. In glacial periods this trapping is reduced several fold and likely results in increased Si(OH) 4 export to the north, and increased Si(OH) 4 production and deposition at the equatorial Pacific which can be expected to reduce surface pCO 2 . The connections between the eastern equatorial Pacific export production and Southern Ocean Si trapping may provide a major biogeochemical feedback system with implications for contemporary and paleoclimatology.

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Section: Low Si(oh) 4 -High No 3 Low Chlorophyll Areasmentioning

confidence: 99%

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Dugdale

Wilkerson

2001

Sci. Mar.

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“…These eastern boundary waters merge to supply the westwardflowing South Equatorial Current (SEC), which is subject to the divergence, north and south of the equator, and generates upwelling of subsurface waters having high salinity, C T , and nutrient concentrations to the surface (Kessler, 2006). Since chlorophyll concentrations remain low and the macronutrients are not depleted, this region is a HNLC (highnutrient/low-chlorophyll) area (Minas et al, 1986).…”

Section: Hydrographymentioning

confidence: 99%

Anthropogenic carbon distribution in the eastern South Pacific Ocean

Goyet

Gonçalves²,

Touratier

2009

Biogeosciences

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“…Net production is sometimes measured by oxygen production (Minas et al 1986), but as has been indicated, the oxygen loss makes this method unsuitable in red tides. Furthermore, neither carbon dioxide nor phosphate and nitrate can be used because their uptake mechanisms vary with depth.…”

Section: Net Productionmentioning

confidence: 99%

Stoichiometric variations of N P, C and O during a Gymnodinium catenation rod tide and their Interpretation

Fraga¹,

Pérez²,

Figueiras³

et al. 1992

Mar. Ecol. Prog. Ser.

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The chemical parameters 'NO', 'PO' and 'CO' are constants that remain invariable during photosynthesis or remineralization of organic matter. Nevertheless, exceptionally, during a red tide these parameters are no longer constant. Their vertical variation during a Gymnodinium catenatum red tide in the Ria de Vigo, Spain, in October 1986 is described. Stoichiometric equations are obtained for biomass synthesis in the superficial water layer and in the nutricline which are adjusted to the experimental data. From these chemical parameters a new parameter 'NCO' is calculated which remains constant in both normal phytoplankton populations and dinoflagellates endowed with vertical migration and differential synthesis of cellular compounds. With this parameter, the oxygen loss to the atmosphere during the red tide was estimated and a good fit was found with that calculated from the diffusion. This permits the calculation of net accumulated production. From the same parameters, the vertical transport of nutrients produced by the migration of the dinoflagellates is quantified. A good agreement with the spatial distribution of total nitrogen (organic and inorganic) is obtained, if the carbohydrate consumption in respiration is taken into account.

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Productivity in upwelling areas deduced from hydrographic and chemical fields1

Cited by 177 publications

References 42 publications

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Sources and fates of silicon in the ocean: the role of diatoms in the climate and glacial cycles

Anthropogenic carbon distribution in the eastern South Pacific Ocean

Stoichiometric variations of N P, C and O during a Gymnodinium catenation rod tide and their Interpretation

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