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General Session 3: Biological oceanography & global change |
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N2 fixation and it’s transportation in coral holobiont
GS3-46
Huaxia Sheng* , State Key Laboratory of Marine Environmental Science, Xiamen University
Xianhui Wan, State Key Laboratory of Marine Environmental Science, Xiamen University
Weidi Yang, College of Ocean and Earth Sciences, Xiamen University
Guanghe Shao, State Key Laboratory of Marine Environmental Science, Xiamen University
Shuh-ji Kao, State Key Laboratory of Marine Environmental Science, Xiamen University
Presenter Email: hxsheng@xmu.edu.cn
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| Coral reefs are the iconic ecological communities of tropical seas, providing extensive ecosystem goods and services to around 500 million people. It is one of the most productive ecosystems but living in oligotrophic ocean. This has given rise to the ecosystem conundrum, sometimes called “Darwin’s paradox”. One of the hypotheses was proposed that new bioavailable nitrogen produced from nitrogen fixation by cyanobacteria and heterotrophic bacteria, which provides the "new" N for the oligotrophic coral reef ecosystem and thus plays an important role in flourishing productivity. However, the transformation of the newly fixed nitrogen within the coral holobiont remains unclear. Here we use 15N-N2 tracer methods to measure N fixation rate of an artificial coral ecosystem, which is consist of Seriatopora hystrix holobiont and a species of crustose coralline algae(CCA). The result shows that, the symbiotic N fixation microbes in CCA and Seriatopora hystrix are showing the similar N fixation rate of 4 nmolN mgN-1 d-1. The "new" N fixation by symbiotic microbes in Seriatopora hystrix holobiont can be transferred to symbiodiniums (zooxanthellae) and coral host cells, implying the redistribution and reuse of "new" N in coral holobiont. |
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