New Zealand Journal of Marine and Freshwater Research abstracts

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Plankton ecology and productivity, nutrient chemistry, and hydrography of Tasman Bay, New Zealand, 1982-1984

A. L. MACKENZIE P. A. GILLESPIE

Cawthron Institute P. O. Box 175, Nelson New Zealand

Abstract The water column at a single near-shore location in Tasman Bay was intensively sampled between April 1982 and March 1984 at 1-2 month intervals. Lowest salinities and highest dissolved nutrient concentrations occurred during the winter of both years. Nitrate-N was the most commonly measurable inorganic nitrogen species. Inorganic N:P:Si ratios suggest that among the major nutrients nitrogen was in the greatest demand. The phytoplankton community structure and phenology was typical of a temperate neritic environment, though considerable year to year variations occurred in the specific composition and the magnitude of production. Periods of relative abundance of some potential nuisance species were documented. Small nannoplanktonic species (< 10 urn) were always an important and frequently a dominant component of the photosynthetic community. The winter/spring diatom bloom re-occurred as the most productive event. In surface waters, phytoplankton biomass ranged from 19-208 mgC m ³. In situ rates of photosynthesis ranged from 202-1981 mgCnr²d-'. The magnitude of phytoplankton blooms appeared to be related to preceeding high rainfall events. Unusually large floods during the winter of 1983 lead to a major peak in productivity by a mixed diatom/Mesodinium rubrum bloom. Annual net productivities of 121 gC m² y-' and 171 gC rrr² y ' during 1982 and 1983 respectively, were estimated.

Keywords Tasman Bay; neritic; nutrients; hydrography; phytoplankton; primary production; phenology; biomass; zooplankton; new records; marine ecology Received 17 June 1985; accepted 17 December 1985

New Zealand Journal of Marine and Freshwater Research, 1986, Vol. 20 : 365-395 Received 17 June 1985; accepted 17 December 1985

PDF file of entire paper: medium quality (2181K); (scanned from paper original: notes about this process)

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