营养盐和碳源对海洋激发效应影响和微生物响应机制探索研究

Labile organic carbon and nutrient inputs can increase in-situ recalcitrant organic matter decomposition rates, leading to more organic carbon consumption, which is defined in term of priming effect (PE) which is important to carbon cycling due to the impact on different carbon pool. PE is mainly studied in the soil and the north hemisphere fresh water. However few study focus on PE in the ocean despite the microbial process and mechanism are poorly understood. Based on our previous knowledge and understanding of PE, bioassay experiment is applied to explore priming effect within South China Sea surface water as well as the impact of nutrient and organic carbon availability and microbial process and mechanisms involved in by various chemical and biological parameters, such as total organic carbon concentration and inorganic nutrient availability, variation of ecto-enzymatic activity and microbial community structure and diversity and microbial response. It will give us some better and new understanding about PE in the ocean. Our project would like to figure out two key scientific questions: 1) the relationship between PE and inorganic nutrient and organic carbon availability; 2) build the bridge between microbial activity and community structure and diversity and PE in the ocean.

激发效应(Priming Effect，PE)是指外源营养盐和碳源的加入，导致更多原位惰性有机碳被降解的现象，它能够影响各碳库之间的平衡，对全球碳循环产生重要影响。PE在土壤圈和水圈（北半球的淡水环境）广泛存在，但在海洋中研究极少，且微生物在PE中的作用机制并不清楚，而这些是深入研究PE的关键。本项目申请人拟在南海各典型环境中利用经典培养实验，通过监测总有机碳和营养盐等指标的变化，分析微生物胞外酶活性和群落结构组成的时空差异，研究微生物生产力和丰度的响应策略，意在揭示营养盐和碳源对PE的影响及对应关系、深入探讨微生物在PE中发挥作用的机制，为海洋PE研究带来系统认识。本项目拟解决2个关键科学问题：1）各典型海洋环境PE的现状，及其与营养盐和碳源的对应关系；2）PE与微生物代谢活性和群落结构组成时空变化的内在联系和相互作用机制。

激发效应在土壤圈和水圈广泛存在，对全球碳循环具有重要影响。但海洋中激发效应和微生物群落的关系和作用机制不甚明了。本项目在南海陆架海和海盆区域开展了原位培养实验，研究了外源碳源和（或）营养盐输入对海洋激发效应的影响，系统分析了不同时间和空间的微生物群落和个体的细菌生产力、胞外酶活性等代谢过程参数，重点采集和研究了时间序列上的细菌群落结构差异。在未出现激发效应的陆架海区域，细菌生产力和胞外酶群落代谢活性与细菌单细胞代谢活性在时间序列上的变化趋势并不一致；而出现激发效应的海盆区细菌群落和个体代谢活性的变化趋势整体一致。微生物代谢多过程参数和细菌群落结构网络分析结果表明，碳源、营养盐输入引发的群落结构和代谢多样性将会导致更多惰性有机碳的降解，这可能是导致激发效应的关键微生物生态学机制。本项目研究链接了微型生物代谢过程参数与细菌群落结构，为认识激发效应微生物和环境调控机制提供了新的视角。