New Zealand Journal of Marine and Freshwater Research abstracts

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Benthos associated with two New Zealand coastal outfalls

D. S. ROPER

D. G. SMITH

G. B. READ

Water Quality Centre
Division of Water Sciences
Department of Scientific and Industrial Research
P. O. Box 11-115, Hamilton, New Zealand

Abstract The benthic ecological impacts of 2 New Zealand ocean outfalls were studied. They are the country's largest (discharging 0.8 m³ s'¹) at Hastings, and longest-established (operating since 1965 and with a present discharge of 0.28 m³ s"¹) at Gisbome. Both discharge essentially biodegradable domestic and food-processing-industry wastes. Samples were collected about each outfall and analysed for particle size, oil and grease, readily oxidisable carbon (ROC), total Kjeldahl nitrogen (TKN), volatile solids, and macrofauna. Changes in the sediments indicated that the effluents contained inorganic paniculate material in the mud/very fine sand size range. Peaks in concentrations of oil and grease, ROC, TKN, and volatile solids occurred at the diffusers. Numbers of taxa were low near the outfalls, but increased with distance away. Numbers of individuals were also low at the outfalls, increasing within 100 m, before dropping to normal levels. No grossly polluted zone, devoid of macrofauna, was found; however, it appeared that a "polluted" zone occurred within 200 m of the diffusers and a "transitional" zone extended to between 800 and 1600 m from the Gisborne outfall, and 400 and 1600 m at Hastings. Multivariate classification and ordination indicated that over the area sampled, the discharges were the main factor shaping the patterns of community structure.

Keywords outfalls; sewage effluent; pollution; benthos; sediments; Hawke Bay; Poverty Bay

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23: 295-309 0O2&-S330/S9P302-O29 New Zealand Journal of Marine and Fresh water Research,1989,Vol.23: Received 18 April 1988; accepted 29 July 1988

PDF file of entire paper: medium quality (1036K); (scanned from paper original: notes about this process)

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