New Zealand Journal of Marine and Freshwater Research abstracts

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Uptake of nitrate and ammonium, and distribution of related variables, in the upwelled plume of western Cook Strait / Taranaki Bight, New Zealand

ANTHONY B. VINER1 VAUGHAN H. WILKINSON2

1Taupo Research Laboratory
Division of Water Sciences
Department of Scientific and Industrial Research
P.O. Box 415, Taupo, New Zealand
2Ministry of Agriculture and Fisheries Private Bag, Auckland, New Zealand

Abstract To distinguish the manner of spread of upwelling effects in the Cook Strait/Taranaki Bight (New Zealand) region, nitrogen uptake and the distribution of nutrients and chlorophyll a are described. NO₃ concentrations were closely linked to upwelled water, but this was distributed irregularly and noi: necessarily with the upwelling focus. NH₄, SRP, aid chlorophyll a showed varying degrees of association with recycling processes, but linear correlations were not present. NO₃ uptake was strongly inhibited by ambient NH₄, but not completely. There was no evidence of either N or P limitation of total planktonic biomass, and there was indirect evidence from C/N uptake and cellular ratios that a high growth rate prevailed. N uptake increased with irradiance (= decreasing depth) similar to photosynthesis, but without high light inhibition, and could be related to light by a simple equation. The inegularity of distribution of features suggests that future modelling of the phytoplankton biomass in the region could benefit from analysis of event occurrence rather than of evenly progressive changes.

Keywords chlorophyll; nitrogen; nitrogen dynamics; marine upwelling; phosphorus; phytoplankton

New Zealand Journal of Marine and Freshwater Research, 1988, Vol. 22: 565-576 Crown copyright 1988Received 26 November 1987; accepted 26 January 1988

PDF file of entire paper: medium quality (967K); (scanned from paper original: notes about this process)

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