New Zealand Journal of Marine and Freshwater Research abstracts

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Variations of upwelling and associated nutrient nitrogen dynamics off the north-west coast of South Island, New Zealand

A. B. VINER¹

V. H. WILKINSON²

^1.Taupo Research Laboratory
Department of Scientific and Industrial Research
P. O. Box 415
Taupo, New Zealand

²Ministry of Agriculture and Fisheries Private Bag Auckland, New Zealand

Abstract The surface distribution and metabolic uptake of nitrate and ammonium were investigated as they related to the movements of water in the upwelling zone off the north-west coast of South Island, New Zealand. Analyses were also made of chlorophyll a and paniculate nitrogen as indicators of phytoplankton biomass. The movement of water and resulting dispersion from the upwelling focus were shown to differ greatly from day to day; this could confound simple correlations between nutrient nitrate and phytoplankton. A suitable model to investigate metabolic processes due to influx of fertile upwelled water which could avoid this problem can be based upon assays of NO₃ and NH₄ uptake by the plankton. These assays, done with ¹⁵NH₄ and ^I5NO₃, could provide an operational index for identifying the zone of nett production due to nutrient upwelling.

Keywords nitrogen distribution; nitrogen uptake; ¹⁵N utilisation; coastal upwelling; production; South Island; New Zealand

New Zealand Journal of Marine and Freshwater Research, 1987, Vol. 21: 253-266 0028-8330/87/2102-0253$2.50/0 © Crown copyright 1987 Received 30 June 1986; accepted 3 November 1986

PDF file of entire paper: medium quality (1347K); (scanned from paper original: notes about this process)

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