Periodic ammonium pulses: are they important for the uptake kinetics of Isochrysis galbana?
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117, more
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| Keywords |
Physics > Mechanics > Kinetics
Temporal variations > Periodic variations
Uptake
Isochrysis galbana Parke, 1949 [WoRMS]
ISE, French Polynesia, Society I., Tahiti [Marine Regions]
Marine/Coastal |
| Abstract |
In a megatidal coastal system, high tidal currents can lead to periodic reinjection of nutrients via the water/sediment interface. This study investigates the phytoplankton response to periodic ammonium pulses (every 5h20) in a nitrogen-limited culture of Isochrysis galbana. Results show that cells use additional ammonium. The cell response is not instantaneous and an adaptation period is observed in experiments. This period is characterized by (i) a decrease in latency stage during 10 mn after one pulse, (ii) an alternance of uptake/excretion processes decreasing throughout the experiment, (iii) an increasingly high and rapid surge-uptake phenomenon until pulse 6. We raise the question whether the Michaelis-Menten equation classically used to describe uptake processes is adequate in such an intermittent background. |
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