Tsuneo TanakaCorrespondence: Laboratoire d’Océanographie physique et Biogéochimique (LOPB) UMR 6535-CNRS, Centre d’Océanologie de Marseille (COM), Université de la Méditerranée |
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Application of specific affinity of bacteria to understand organic C dynamics in pelagic system |
| The mechanism that phytoplankton convert inorganic carbon into organic carbon that is transferred from the surface to the deep sea via sinking particles, mixing of dissolved organic matter, and active transport by animals - known as the biological C pump - plays an important role in global C cycle. One can assume that an efficient biological C pump requires a condition which reduces mineralization of organic C (i.e. back to CO2) within euphotic layer. In the lower part of the pelagic plankton food web, both phytoplankton and bacteria use nutrients such as inorganic N and P. That is, consumption of degradable DOC by bacteria can be controlled by availability of inorganic nutrients: competition for nutrients with phytoplankton. Measuring nutrient availability or limitation for phytoplankton and bacteria is therefore important to better understand organic C cycle in pelagic system. However the extent of nutrient limitation is not necessarily easy to measure for natural plankton communities. The specific affinity for substrate uptake is theoretically the best parameter to determine the substrate uptake ability by osmotrophs under low substrate concentrations, and is analogous to a specific clearance rate by filter feeding zooplankton: the volume cleared for food (substrate) per unit biomass and time. Results from two mesocosm studies will be presented to argue how specific affinities for substrate (glucose as labile DOC, and phosphate) can be used to understand organic C dynamics in the pelagic system. |
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Ort |
| 09.07.2009 15:00 Uhr Großer Hörsaal |
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