In situ Growth and Photosynthetic Characteristics of Oscillatoria mougeotii in the Metalimnetic Layer of the Small Eutrophic Lake Nakanuma

Abstract

In situ growth and photosynthetic characteristics of Oscillatoria mougeotii were studied in the metalimnetic layer of a small eutrophic lake. Population growth of O.maugeotii showed a logistic curve and the mean increase rate of population was 0.086 (day^-1). Photosynthesis of individual species in the natural phytoplankton community was measured by grain density autoradiography. The photosynthetic nature of O.mougeotii represented by the light-photosynthesis curve was a shade type with a steeper initial slope and a low maximum photosynthetic rate.The growth curve of O. mougeotii estimated by a model using the light-photosynthesis curve and light conditions coincided fairly well with the observed curve. Thus it was concluded that the population development of O. mougeotii in the metalimnion would be mainly due to the in situ photosynthetic growth.