TY - JOUR
T1 - Size-fractionated primary production and nitrogen assimilation in the northwestern Indian Ocean
AU - Owens, N. J.P.
AU - Burkill, P. H.
AU - Mantoura, R. F.C.
AU - Woodward, E. M.S.
AU - Bellan, I. E.
AU - Aiken, J.
AU - Howland, R. J.M.
AU - Llewellyn, C. A.
N1 - Copyright © 1993 Published by Elsevier Ltd.
The author was not affiliated to SAMS at the time of publication
PY - 1993
Y1 - 1993
N2 - Rates of phytoplankton production and nitrogen assimilation were measured at various stations along a transect in the northwestern Indian Ocean, from near the equator, northwards into the upwelling system off the Arabian peninsula, during September-October 1986. The measurements were made using in situ incubation techniques with the simultaneous use of 14C and 15N isotopes. Samples were fractionated after the incubations into three size classes: 0.2-0.8μm, 0.8-5.0 μm, and >5.0μm for the 14C incubations; and <5.0μm and >5μm for the 15N incubations. The assimilation of nitrate and ammonium was measured. These measurements were supported by a detailed description of the horizontal and vertical distributions of chlorophyll, temperature and underwater light field, by the deployment of a towed undulating oceanographic recorder. Rates of primary production ranged from approximately 0.5 g C m-2 day-1 at the equator, reducing to <0.3 in the oligotrophic gyre in the central northern Indian Ocean, and to >2.5 in the upwelling region off the coast of Oman; total nitrogen assimilation followed a similar pattern. Very significant variations in the size distribution of the activity of the plankton were observed. Over 75% of the carbon and nitrogen assimilation was in the <5 μm fraction at the south of the transect; this decreased to approximately 10% in the upwelling region. New production (φratios) varied between approximately 0.1 in the oligotrophic regions and 0.9 in the upwelling region.
AB - Rates of phytoplankton production and nitrogen assimilation were measured at various stations along a transect in the northwestern Indian Ocean, from near the equator, northwards into the upwelling system off the Arabian peninsula, during September-October 1986. The measurements were made using in situ incubation techniques with the simultaneous use of 14C and 15N isotopes. Samples were fractionated after the incubations into three size classes: 0.2-0.8μm, 0.8-5.0 μm, and >5.0μm for the 14C incubations; and <5.0μm and >5μm for the 15N incubations. The assimilation of nitrate and ammonium was measured. These measurements were supported by a detailed description of the horizontal and vertical distributions of chlorophyll, temperature and underwater light field, by the deployment of a towed undulating oceanographic recorder. Rates of primary production ranged from approximately 0.5 g C m-2 day-1 at the equator, reducing to <0.3 in the oligotrophic gyre in the central northern Indian Ocean, and to >2.5 in the upwelling region off the coast of Oman; total nitrogen assimilation followed a similar pattern. Very significant variations in the size distribution of the activity of the plankton were observed. Over 75% of the carbon and nitrogen assimilation was in the <5 μm fraction at the south of the transect; this decreased to approximately 10% in the upwelling region. New production (φratios) varied between approximately 0.1 in the oligotrophic regions and 0.9 in the upwelling region.
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U2 - 10.1016/0967-0645(93)90053-P
DO - 10.1016/0967-0645(93)90053-P
M3 - Article
AN - SCOPUS:0027511020
SN - 0967-0645
VL - 40
SP - 697
EP - 709
JO - Deep-Sea Research Part II
JF - Deep-Sea Research Part II
IS - 3
ER -