New Zealand Journal of Marine and Freshwater Research abstracts

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Hypolimnetic oxygen consumption in Lake Taupo, New Zealand: a preliminary assessment

A. B. VINER

Taupo Research Laboratory
Division of Water Sciences
Department of Scientific and Industrial Research
P. O. Box 415, Taupo, New Zealand

Abstract The water quality of Lake Taupo is of great national importance to New Zealand, but development pressures in the catchment require attention to prevent organic enrichment of the water. Observations on the lake were made during 1986-87 to relate hypolimnetic oxygen consumption to organic carbon input from the phytoplankton (¹⁴C photosynthetic production) and to the amount of sedimenting phytoplankton determined in sediment traps. There is some degree of hypolimnetic oxygen deficit, even at least lake stability, and so no excess supply of oxygen by physical means exists to balance any enhanced organic input. Sedimentation rate varied greatly throughout the year. It was mainly controlled by the onset of stratification which radically affected the heavily frustuled diatoms dominant at this time. The species present also influenced sedimentation at other times but to a lesser extent. Both allochthonous input of organic material and nitrification are significant additions to phytoplanktonic production for oxygen consumption, but both amounts are uncertain at present and could be greater than estimated. Total organic input would probably have to approximately double to start deoxygenation of the sediment at maximum stability and so induce a radical change in the ecosystem.

Keywords Lake Taupo; organic carbon; oxygen consumption; primary production; water quality; sedimentation rates

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23: 381-391 0028-8330/89/2303-0381$2.50/0 © Crown copyright 1989 Received 19 September 1988; accepted 16 February 1989

PDF file of entire paper: medium quality (858K); (scanned from paper original: notes about this process)

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