New Zealand Journal of Marine and Freshwater Research abstracts

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Seasonal variation of heterotrophic potential in Lake Rotoroa

P. A. Gillespie

and

M. J. Spencer

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

Abstract A 20-fold seasonal variation in heterotrophic potential (V.,,) for glucose uptake was observed in Lake Rotoroa during a 3-year sampling programme. Peaks in activity coincided approximately with maximum surface water temperature, but the large variations suggest quantitative and/or qualitative changes in the heterotrophic microbial population. V.., values in subsurface samples taken from within dense beds of Elodea canadensis were on average nine times greater than those in surface samples from above the beds. Values for V_ma*, ATP, and chlorophyll a (Chi a) decreased and nitrogen and phosphorus concentrations increased slightly after a drastic decline in the extent of Elodea beds occurred in 1974. The seasonal ranges of the above parameters were similar to published values for oligotrophic lakes: V_ma*, less than 0.001-0.02 /tg.L-'Ji-¹; ATP, 0.01-0.09 ^g.L-¹; Chi a, 0.3-1.4 ^g.L"¹; total-N, 0.03-0.22 mg.L-¹; total-P, 0.001-0.013 mg.L-¹.

Keywords Heterotrophic potentials, Oligotrophic lakes, Seasonal variation, Elodea canadensis, Nutrients, Lake Rotoroa.

New Zealand journal of Marine & Freshwater Research, 1980, 14 (1): 15-21
Received 29 March 1979; revision received 8 November 1979

PDF file of entire paper: medium quality (465K); (scanned from paper original: notes about this process)

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