New Zealand Journal of Marine and Freshwater Research abstracts

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Hydrology and near-surface nutrient distribution along the South Otago continental shelf, New Zealand, in summer and winter 1986

DAVID J. HAWKE

Department of Chemistry University of Otago P.O. Box 56, Dunedin, New Zealand

Abstract The 3 Otago coastal water masses (Neritic water, subtropical Southland Current water, and Subantarctic Surface Water) defined in the literature were identified on 1 cruise in early summer and 1 in mid winter. Winter results showed that Neritic water is derived from the Clutha River. During winter the Southland Current was characterised by temperatures between 9.0 and 10.6°C and a salinity range of 34.4 to 34.9 X 10"³. During summer a thermocline and pycnocline were observed at 30-50 m depth sloping down toward the coast. Low-salinity Neritic water was less apparent than in winter. Summer nutrient levels were depleted over all of the continental shelf, relative to winter. This is probably caused by the enclosure of coastal surface waters inshore of the pycnocline. Reactive Si was conservative in winter regardless of water mass. Reactive P was approximately constant in Neritic water and Southland Current water. In summer, neither nutrient was conservative.

Keywords subtropical convergence; continental shelves; Clutha River; South Island; phosphorus; silicon

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23:411-420 0028-8330/89/2303-041 l$2.50A) © Crown copyright 1989 Received 4 October 1988; accepted 23 November 1988

PDF file of entire paper: medium quality (680K); (scanned from paper original: notes about this process)

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