TY - JOUR
T1 - Primary production and nitrogen assimilation in the North sea during July 1987
AU - Owens, N. J.P.
AU - Woodward, E. M.S.
AU - Aiken, J.
AU - Bellan, I. E.
AU - Rees, A. P.
N1 - Copyright © 1990 Published by Elsevier B.V.
The author was not affiliated to SAMS at the time of publication
Funding Information:
Acknowledgements.--We gratefully acknowledge the Master, officers and crew of the RRS Challenger. We thank R.J.M. Howland for assistance with nutrient analyses, A.J. Bale and D.B. Robins for assistance with sampling and E. Drury for assistance with the 15N measurements. We thank Europa Scientific Ltd. for the loan of the 15N analysis apparatus and A. Park and T. Preston for assistance in commissioning the instrument prior to sailing. This work forms part of Laboratory Programme II of the Plymouth Marine of Laboratory Programme II of the Plymouth Marine Laboratory, a component body of the UK Natural Environment Research Council, and was funded, in
Funding Information:
part, by the UK Department of the Environment under contract number PECD 7/7/195.
PY - 1990/5/1
Y1 - 1990/5/1
N2 - An extensive survey of the whole of the North Sea, carried out in July 1987, is described. The study concentrated on the measurement of surface water inorganic nutrient concentrations and concomitant rates of primary production (14C) and nitrogen assimilation (15N). Primary production was investigated using size fractionation techniques. Three vertical profiles of primary production and nitrogen assimilation were also investigated. Much of the North Sea exhibed thermal stratification. Surface nutrient concentrations were low and chlorophyll concentrations typically <1 mg m-3. More than 75% of the primary production was attributable to cells <5 μm in diameter. Ammonium assimilation accounted for most of the nitrogen assimilation. The water column was vertically well mixed in the coastal zones. Here, inorganic nitrogen concentrations were high (e.g. up to 25 μmol NO3- with chlorophyll concentrations up to 10 mg-3, and organisms >5 μm diameter accounted for most of the primary production. As in offshore regions ammonium accounted for the major part of the nitrogen assimilated. A 115 km section obtained using an undulating oceanographic recorder showed that in certain regions of the North Sea physical features acted to increase the dependence of the phytoplankton on nitrate.
AB - An extensive survey of the whole of the North Sea, carried out in July 1987, is described. The study concentrated on the measurement of surface water inorganic nutrient concentrations and concomitant rates of primary production (14C) and nitrogen assimilation (15N). Primary production was investigated using size fractionation techniques. Three vertical profiles of primary production and nitrogen assimilation were also investigated. Much of the North Sea exhibed thermal stratification. Surface nutrient concentrations were low and chlorophyll concentrations typically <1 mg m-3. More than 75% of the primary production was attributable to cells <5 μm in diameter. Ammonium assimilation accounted for most of the nitrogen assimilation. The water column was vertically well mixed in the coastal zones. Here, inorganic nitrogen concentrations were high (e.g. up to 25 μmol NO3- with chlorophyll concentrations up to 10 mg-3, and organisms >5 μm diameter accounted for most of the primary production. As in offshore regions ammonium accounted for the major part of the nitrogen assimilated. A 115 km section obtained using an undulating oceanographic recorder showed that in certain regions of the North Sea physical features acted to increase the dependence of the phytoplankton on nitrate.
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U2 - 10.1016/0077-7579(90)90015-9
DO - 10.1016/0077-7579(90)90015-9
M3 - Article
AN - SCOPUS:0025669499
VL - 25
SP - 143
EP - 154
IS - 1-2
ER -