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Biogeochemistry in oligotrophic ocean gyres
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A Modelling Study on a Ciliate, Synechococcus and heterotrophic bacterial System
P-M2-06-S
Lice Wang* , State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
Wenxin Lin,
Qiang Zheng,
Ya-Wei Luo,
Presenter Email: 22320161151344@stu.xmu.edu.cn |
| Synechococcus is one of main species of marine primary producers. The grazing on Synechococcus by zooplankton such as ciliates contribute to the base of the marine foodweb. The heterotrophic bacteria decompose debris and dissolved organic matter (DOM) and can also be predated by cilites, forming the microbial loop. Ciliate thus acts as an important link between the microbial loop and the food chain. Therefore, studying the food preference of ciliate on Synechococcus and heterotrophic bacteria is important for understanding the energy flows and material cycles in marine ecosystems. In this study, we cultivated with four levels of initial abundance of Synechoccus and heterotrophic bacteria together, and added one ciliate to each incubation system. They were cultured for 11 days and the daily abundance of these microorganisms was measured. We then constructed a numerical model to simulate this system, and optimization method was used to minimize the difference between the model and the observations. The results show that, contrary to traditional opinions, the ciliates preferred to predate on Synechococcus than heterotrophic bacteria, and the relative preference varied with abundance of the prey. The production of DOM and its usage by heterotrophic bacteria appeared to be the key processes for a successful simulation of the system, indicating that the recycle of DOM played an important role in this system. |
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