首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Nitrate and phosphate uptake kinetics of the harmful diatom Eucampia zodiacus Ehrenberg,a causative organism in the bleaching of aquacultured Porphyra thalli
Authors:Tetsuya Nishikawa  Kenji Tarutani  Tamiji Yamamoto
Institution:1. Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva s/n, 18071 Granada, Spain;2. Instituto Universitario de Investigación del Agua, Universidad de Granada, C/ Ramón y Cajal, 4, 18071 Granada, Spain;3. Estación de Fotobiología Playa Unión, Casilla de Correos 15, 9103 Rawson, Chubut, Argentina;4. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina;1. Institute of Marine Biology, National Taiwan Ocean University, Keelung 202, Taiwan, ROC;2. Institute of Marine Environmental Chemistry and Ecology, National Taiwan Ocean University, Keelung 202, Taiwan, ROC;3. Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 202, Taiwan, ROC
Abstract:The diatom Eucampia zodiacus Ehrenberg is a harmful diatom which indirectly causes bleaching of aquacultured Nori (Porphyra thalli) through competitive utilization of nutrients during bloom events. In the present study, we experimentally investigated the nitrate (N) and phosphate (P) uptake kinetics of E. zodiacus, Harima-Nada strain. Maximum uptake rates (ρmax), which were obtained by short-term experiments, were 0.777 and 0.916 pmol cell?1 h?1 for nitrate and 0.244 and 0.550 pmol cell?1 h?1 for phosphate at 9 and 20 °C, respectively. The half-saturation constants for uptake (Ks) were 2.59 and 2.92 μM N and 1.83 and 4.85 μM P at 9 and 20 °C, respectively. Although the maximum specific uptake rate (Vmax; Vmax = ρmax/Q0, Q0; minimum cell quota) and Vmax/Ks for nitrate at 9 °C are about 1/2 of those obtained at the optimum temperature (20 °C), they are still higher than those obtained for many other phytoplankton at their optimum temperature conditions for uptake. These results suggest that E. zodiacus utilizes nitrogen efficiently at low water temperature, and it is one of the important factors causing the serious damage to Porphyra thalli by bleaching due of this species. For phosphate, the Ks values of E. zodiacus were higher than those reported for other species; the Vmax and Vmax/Ks values were much lower than those of other diatoms such as Skeletonema costatum (Greville) Cleve. These results suggest that E. zodiacus is disadvantaged compared to other diatom species during competitive utilization of phosphate.
Keywords:
本文献已被 ScienceDirect 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号