An unexpected nitrate distribution in the tropical North Atlantic at 18°N, 30°W—implications for new production.

Koeve, Wolfgang , Eppley, R. W., Podewski, S. and Zeitzschel, Bernt (1993) An unexpected nitrate distribution in the tropical North Atlantic at 18°N, 30°W—implications for new production. Deep Sea Research Part II: Topical Studies in Oceanography, 40 (1-2). pp. 521-536. DOI 10.1016/0967-0645(93)90030-Q.

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Abstract

During a R.V. Meteor JGOFS-NABE cruise to a tropical site in the northeast Atlantic in spring 1989, three different vertical regimes with respect to nitrate distribution and availability within the euphotic zone were observed. Besides dramatic variations in the depth of the nitracline, a previously undescribed nose-like nitrate maximum within the euphotic zone was the most prominent feature during this study. Both the vertical structure of phytoplankton biomass and the degree of absolute and relative new production were related to the depth of the nitracline, which in turn was dependent on the occurrence/non-occurrence of the subsurface subtropical salinity maximum (S(max)). The mesoscale variability of the nitracline depth, as indicated from a pre-survey grid, and published data on the frequent occurrence of the S(max) in tropical waters suggest higher variability of new production and F-ratio than usually expected for oligotrophic oceans. The importance of salt fingering and double diffusion for nitrate transport into the euphotic zone is discussed.

Document Type: Article
Keywords: Biological Oceanography; DEEP CHLOROPHYLL MAXIMUM; OLIGOTROPHIC OCEAN; SARGASSO SEA; SALT FINGERS; MIXED LAYER; PHYTOPLANKTON; OXYGEN; NITROGEN; WATER; VARIABILITY
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Expeditions/Models/Experiments:
Date Deposited: 07 Feb 2012 12:12
Last Modified: 21 Jan 2019 15:57
URI: https://oceanrep.geomar.de/id/eprint/13661

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