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Special Session 3: Size matters or not, particles export in marine environments |
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Silicate dynamic during the degradation of cyanobacterium Synechococcus in the oligotrophic seawater
SS3-07
Yifan Zhu* , State key laboratory of marine environmental sciences, Xiamen University, PR China
Tiantian Tang, State key laboratory of marine environmental sciences, Xiamen University, PR China
Presenter Email: yfzhu@stu.xmu.edu.cn
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| Picoplankton has been considered to contribute more than half of the primary production in oligotrophic oceans. However, their role in biological pump which transports carbon from surface to deep ocean was thought to be of less importance due to their small size. Recently, silicate deposition during decomposition of cyanobacteria was found to enhance the export of picoplankton to the deep ocean by producing Si- organic matter (Si-OM) with relatively high BSi:POC ratio(biogenic silicon : particulate organic carbon), which potentially contributes to 43% of the POC flux in Sargasso Sea. To further evaluate the contribution of Si-OM to the POC export in an oligotrophic marginal sea, South China Sea (SCS), we studied the dynamic of Si-OM during the degradation of Cyanobacterium Synechococcus cells (WH7803) grown in the surface water of South China Sea without silicate amendment. The bacterial community was inoculated from the coastal seawater (Wuyuan Bay, XM, CN) with zooplankton and larger phytoplankton removed. Subsamples including BSi, POC, DOC, nutrients and bacterial abundance were collected over the 30-day incubation. The distribution of silicon and carbon in different reservoirs was primarily traced as a response to the degradation of synechococcus cells. The results were compared with controls without bacterial inoculation. The BSi:POC ratio derived from this incubation was applied to evaluate the relative abundance of POC flux due to the production of Si-OM in SCS. |
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