New Zealand Journal of Marine and Freshwater Research abstracts

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Seasonal hydrology of Port Fitzroy, Great Barrier Island, New Zealand

R. W. Hickman

Fisheries Research Division, Ministry of Agriculture and Fisheries, P.O. Box 19062, Wellington, New Zealand

Abstract At 2-monthly intervals between March 1974 and January 1975 seawater temperature and salinity (at 0 m and 5 m depths) and turbidity (as Secchi disc visibility) were measured in Port Fitzroy and adjacent bays on Great Barrier Island (36°11'S, 175°21'E). A seasonal pattern was evident in all three parameters. Variation between depths and between high and low tides was generally only slight, although differences of up to 3.6°c and 12.58%₀ were recorded occasionally. Maximum temperatures (22—23°e) occurred in January, with minima (13-14°c) in July. Salinities were generally between 35.0 and 35.6%_O, but values as low as 22.25%o at the surface were recorded after heavy rainfall. Secehi disc visibility measurements of turbidity varied between 2.0 and 12.5 m, but were usually 5-9 m.

A graded series of four generalised areas was distinguished, ranging from sheltered, almost estuarine inner bays, to exposed open water with properties similar to outer Hauraki Gulf water.

The circulation through Port Fitzroy comprises the main exchange of water through the northern entrance channel, causing a southerly movement of water on the flood tide and a northerly movement on the ebb, together with a small compensatory exchange through the narrow southern entrance.

New Zealand Journal of Marine & Freshwater Research, 1979, 13(2): 231 - 240.
Received 26 June 1978; revision received 26 September 1978 Fisheries Research Division Publication 339

PDF file of entire paper: medium quality (880K); (scanned from paper original: notes about this process)

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