牡蛎常被用于水体富营养化治理，其生物沉积对沉积物碳氮循环有较大影响。微生物是生态系统中生源要素生物地球化学循环最主要的参与者，为全面了解牡蛎对富营养化控制机理及其在生态修复中的作用，需探究牡蛎驱动底栖环境中微生物群落组成变化的方式，即随机性和决定性过程的贡献比率。关于此目前尚无针对性研究。深圳湾是一个富营养化状况严重的海湾，湾内香港侧有近10平方公里超30年的牡蛎养殖区（Crassostrea rivularis），为研究提供了合适的生境。本研究以深圳湾牡蛎养殖区和非养殖区的底栖微生物为对象，采用过程分析方法，开展微生物群落组成定量分析，以明确牡蛎影响下的微生物生态过程及影响因素。丰度及多样性分析表明，牡蛎养殖增加了微生物群落的多样性及异质性，产生更多特异性物种。然后，我们从环境参数和微生物间相互作用两类因素分析了差异的可能原因。对于环境因素，我们确定铵态氮和微生物群落在养殖区和非养殖区间的差异相关，而其它环境因子更多在上下层差异中起作用。对于生物间相互作用，我们则发现关键物种在一定程度可以反映群落结构特征。过程分析的结果显示，上层两个区域微生物群落之间的扩散限制强于下层，但如果以关键物种进行过程分析则显示上层扩散限制弱于下层。接下来，我们通过模型选择确定了pH是影响微生物群落组成决定性过程的因素，但pH没有显示出受到牡蛎养殖的影响。含水率则则被确定为随机性因素，牡蛎养殖使其升高。最后，通过整合环境因子和关键物种的模型选择，我们发现，关键物种对微生物群落组成的影响也包括决定性和随机性过程，而牡蛎养殖则主要通过随机性过程影响关键物种。因此，我们将牡蛎对底栖微生物群落的影响途径归结为三个方面。首先，牡蛎剧烈改变其下方沉积物微生物群落组成，这些微生物无法及时地扩散，造成了表观上扩散限制的情况，增加了周边物种的组成乃至功能的异质性。其次，牡蛎养殖增加了含水率，促进了功能异质性的群落相互混合。最后，牡蛎还可能通过影响环境决定性地改变微生物群落。另外，由于牡蛎对关键物种的影响是间接的，关键物种不会发生突然变化而干扰微生物群落的网络结构和功能。这意味着，牡蛎养殖在不影响底栖微生物群落网络结构稳定的前提下，可能增加其功能的多样性。

Oyster culture, with its great influence on carbon and nitrogen cycle in sediments, is widely used as a biological means to deal with eutrophication of waters. In order to fully understand the role of oysters in ecological restoration, it is necessary to explore the ratio of stochastic and determinstic ways through which these animals drive the changes in benthic microbial community profile. However, process analysis method has not been adoped to evaluate the impact of oysters on the benthic microbial community. In the present study, we took Shenzhen Bay as the reserch site since it is under heavy eutrophication and nearly 10 km2 of the bay has been employed as oyster-cultruing (Crassostrea rivularis) area for more than 30 years. Benthic sediments from oyster culture zones and non-oyster culture zones in shenzhen bay were sampled and measured, and the process analysis method was employed to carry out quantitative analysis of microbial community composition, so as to clarify the microbial ecological process and mechanism under the influence of oysters.We confirmed that oyster culture increases the diversity and heterogeneity of the microbial community and produced more specific species. Then we measured the potential of both environmental factors and microbial interactions as possible pathways through which oyster culture impacts benthic microbe. We determined that ammonium nitrogen is related to the difference between microbial communities from the culture and non-culture area, while other environmental factors played a more important role in dividing communities from the upper and the deeper sediments. The keystone species, to some extent, profile the whole community, but are not strongly affected by oyster culture. The results of process analysis showed that dispersal limitation between the two regions in the upper layer is stronger than that in the lower layer; the according analysis based on key species showed that the diffusion restriction in the upper layer was weaker than that in the lower layer. Through model selection method, we identified pH as a factor related to the deterministic process of microbial community composition, and moisture a stochastic factor. Since pH has not been shown to be affected by oyster culture, we believe that although oyster culture affects microbial community composition through certain determining factors, these factor were not included in the parameters we measured. The moisture can be increased by oyster farming. By model selection based on both environmental factors and of keystone species, we found that keystone species also affect microbial community composition through both deterministic and stochastic way, which are related to environmental factors affected by oyster culture. Therefore, we proposed that oyster culture impacts on the benthic microbial community through three ways. Firstly, benthic microorganisms are continuously and rapidly changed by oysters and, thus, cannot spread quickly enough to conseal the varieties occuring in the upper layer, which increases the diversity and, in turn, function of the peripheral species. Also, oyster culture create higher moisture which assistants mixing of communities with various of function. And Oysters may also change the microbial community through some deterministic factors. Although oysters have impacts on keystone species which are critical in stablizing benthic microbial network, this process is indirect and non-suden and thus would not serve to destroy the microbial community structure and function. Furthermore, since oysters affect keystone species indirectly, the network depending on these important members will not go through sudden changes in structure and function.