|Title:||Productivity in upwelling areas deduced from hydrographic and chemical fields||Authors:||Minas, Hans Joachim
Packard, Theodore Train
|UNESCO Clasification:||251001 Oceanografía biológica||Issue Date:||1986||Publisher:||0024-3590||Journal:||Limnology and Oceanography||Abstract:||A combination of Broenkow’s nutrient oxygen model and Bowden’s residence time evaluation of upwelled waters enabled us to calculate the “net community production” (NCP) in coastal upwelling areas (NW Africa, SW Africa, Peru) and in an open upwelling (Costa Rica Dome). Since NCP represents mainly new production in terms of phosphorus or nitrogen, and since it derives from integrated nutrient consumption over the main production area, a good picture of the average fertility of these zones is obtained. In terms of carbon, NCP averaged 0.6 g C m-2 d-l off Peru, 1.1 off SW Africa, and 2.3 off NW Africa. However, production budget per kilometer of coastline is greater for both Peru and SW Africa than it is for NW Africa. The lower activities off Peru and off SW Africa correspond to a relatively high nutrient-low chlorophyll (HNLC) situation, characterized by a slowly growing phytoplankton standing stock. Such HNLC situations are greatly pronounced in the Costa Rica Dome, with NCP values as low as 0.14 g C m-2 d-l. Herbivorous grazing in the freshly upwelled source water appears to be the most plausible explanation for the low chlorophyll. This mechanism for cropping phytoplankton and retarding nutrient uptake provides a way to spread nutrient input to the open ocean. Italso explains the prevalence of oxygen undersaturation (and CO, oversaturation) in the surface waters of the equatorial upwelling. By using the NW African data and NCP and ammonium excretion rates from the literature we could calculate an Eppley factor (pN0, - : pNO,- + pNH,+) of 0.64.||URI:||http://hdl.handle.net/10553/50877||ISSN:||0024-3590||DOI:||10.4319/lo.19184.108.40.2062||Source:||Limnology and Oceanography [ISSN 0024-3590], v. 31, p. 1182-1206|
|Appears in Collections:||Artículos|
checked on Sep 12, 2021
checked on Aug 28, 2021
Items in accedaCRIS are protected by copyright, with all rights reserved, unless otherwise indicated.