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The Arabian Sea as a high-nutrient, low-chlorophyll region during the late southwest monsoon

DRS at CSIR-National Institute of Oceanography

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Title The Arabian Sea as a high-nutrient, low-chlorophyll region during the late southwest monsoon
 
Creator Naqvi, S.W.A.
Moffett, J.W.
Gauns, M.
Narvekar, P.V.
Pratihary, A.K.
Naik, H.
Shenoy, D.M.
Jayakumar, D.A.
Goepfert, T.J.
Patra, P.K.
Al-Azri, A.
Ahmed, S.I.
 
Subject southwest monsoon
high-nutrient
low chlorophyll
primary production
 
Description Extensive observations were made during the late southwest monsoon of 2004 over the Indian and Omani shelves, and along a transect that extended from the southern coast of Oman to the central west coast of India, tracking the southern leg of the US JGOFS expedition (1994-1995) in the west. The data are used, in conjunction with satellite-derived data, to investigate long-term trends in chlorophyll and sea surface temperature, indicators of upwelling intensity, and to understand factors that control primary production (PP) in the Arabian Sea, focussing on the role of iron. Our results do not support an intensification of upwelling in the western Arabian Sea, reported to have been caused by the decline in the winter/spring Eurasian snow cover since 1997. We also noticed, for the first time, an unexpected development of high-nutrient, low-chlorophyll condition off the southern Omani coast. This feature, coupled with other characteristics of the system, such as a narrow shelf and relatively low iron concentrations in surface waters, suggest a close similarity between the Omani upwelling system and the Peruvian and California upwelling systems, where PP is limited by iron. Iron limitation of PP may complicate simple relationship between upwelling and PP assumed by previous workers, and contribute to the anomalous offshore occurrence of the most severe oxygen (O sub(2)) depletion in the region. Over the much wider Indian shelf, which experiences large-scale bottom water O sub(2)-depletion in summer, adequate iron supply from ducing bottom-waters and sediments seems to support moderately high PP; however, such production is restricted to the thin, oxygenated surface layer, probably because of the unsuitability of the O sub(2)-depleted environment for the growth of oxygenic photosynthesizers
 
Date 2010-07-15T04:58:33Z
2010-07-15T04:58:33Z
2010
 
Type Journal Article
 
Identifier Biogeosciences, vol.7; 2091-2100
no
http://drs.nio.org/drs/handle/2264/3649
 
Language en
 
Relation Biogeosciences_7_2091.jpg
 
Rights © Author(s) 2010. CC Attribution 3.0 License.
 
Publisher European Geosciences Union