Uptake of 13C and 15N (ammonium, nitrate and urea) by Microcystis in Lake Kasumigaura
- 1 January 1987
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Plankton Research
- Vol. 9 (1) , 151-165
- https://doi.org/10.1093/plankt/9.1.151
Abstract
The uptake rate of carbon and nitrogen (ammonium, nitrate and urea) by the Microcystis predominating among phytoplankton was investigated in the summer of 1984 in Takahamaira Bay of Lake Kasumigaura. The Vmax values of Microcystis for nitrate (0.025–0.046 h −1 ) and ammonium (0.15–0.17 h −1 ) were considerably higher than other natural phytoplankton. The ammonium, nitrate and urea uptake by Microcystis was light dependent and was not inhibited with nigh light intensity. The K 1 values were far lower than the Ik values. The carbon uptake was not influenced by nitrogen enrichment. Microcystis accelerated the uptake rate by changing Vmax / Ks value when nitrogen versus carbon content in cells declined. Nitrate was scarcely existent in Takahamairi Bay during the summer, when Microcystis usually used ammonium as the nitrogen source. However, the standing stock of ammonium in the water was far lower than the daily ammonium uptake rates. Therefore, the ammonium in this water had to be supplied because of its rapid turn-over time (−0.7–2.6 h).Keywords
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