Diatom numbers and phosphorus levels in deepwater sediment from lake Taupo, New Zealand

Abstract

Diatom frustules were identified and counted in two cores from the Kuratau Basin, Lake Taupo. Melosira granulata (Ehr.) Ralfs, Cyclotella stelligera Cl. U. Grun., and Asterionella formosa Hassall were the only abundant diatoms. The first two were much more abundant than A. formosa. The latter increased markedly in the sediments of approximately the last 150 y. Phosphorus levels were determined in one of these cores and were found to fluctuate with no apparent trend. Taken together the diatom and phosphorus data suggest that Lake Taupo has been oligotrophic over about 14 centuries, with the likelihood that the more recent appearance of A. formosa in the sediments indicates a change to more enriched conditions. © 1976 Taylor & Francis Group, LLC.