微生物驱动的虾-蟹-贝-鱼多营养层次综合养殖池塘沉积物氮迁出机制

Microorganisms are the key biome driving nitrogen cycle in aquaculture ecosystem and they also play very important role in improving water quality and maintaining the aquaculture system stable. An integrated multi-trophic aquaculture mode of “shrimp-crab-shellfish-fish” has been established by our team in recent years, and it is effective to improve the bottom condition of pond and increase the utilization of feed nitrogen. However, the detailed ecological mechanism involved are still unclear. The accumulation of inorganic nitrogen compounds and anoxic environment in the sediment-water interface could favor the occurrence and proliferation of anammox bacteria. Therefore, we hypothesized that the coupling of nitrification with denitrification and anammox is an important mechanism to remove nitrogen from the sediment of such aquaculture system. In order to clarify the process of nitrogen removal in sediment and its microbiological driving mechanism, several studies have been designed in this project. First, the temporal and spatial variation characteristics of nitrification, denitrification and anammox in the sediment of "shrimp-crab-shellfish-fish" integrated multi-trophic aquaculture pond will be investigated by using both the molecular method of quantitative PCR and measurement of reaction products directly. Then, the coupling dynamic model will be made to clarify the nitrogen removal processes and its microbiological driving mechanism. Moreover, the effect of co-cultured animals on nitrogen removal processes will also be studied. The results obtained in the project will be useful to reveal the ecological mechanism for high efficient utilization of nitrogen nutrients in the integrated multi-trophic aquaculture mode of “shrimp-crab-shellfish-fish”.

微生物是驱动养殖生态系统氮循环的关键生物类群，在改善水质环境、维持系统稳定等方面也发挥着重要作用。项目组研究构建的海水池塘“虾-蟹-贝-鱼”多营养层次综合养殖系统能够明显改善底质环境，提高饵料氮的利用率，但具体的生态学机制还不清楚。池塘沉积物-水界面蓄积的无机氮化合物和低氧环境为厌氧氨氧化菌的存在和增殖营造了有利条件，由此我们推测，硝化、反硝化和厌氧氨氧化反应耦合是驱动沉积物氮迁出的重要机制。本项目通过定量分析硝化、反硝化和厌氧氨氧化反应关键限速酶功能基因表达量和直接检测反应产物含量相结合的方法，深入研究“虾-蟹-贝-鱼”多营养层次综合养殖池塘沉积物的硝化、反硝化和厌氧氨氧化反应时空变化规律，在此基础上构建耦合动力学模型，阐明沉积物的氮迁出过程及其微生物驱动机制，并探讨养殖生物对氮迁出的影响。研究结果将有助于揭示“虾-蟹-贝-鱼”多营养层次综合养殖模式高效利用氮素营养的生态学机制。

微生物是驱动养殖生态系统氮循环的关键生物类群，在改善水质环境、维持系统稳定等方面也发挥着重要作用。海水池塘“虾-蟹-贝-鱼”等多营养层次综合养殖系统能够明显改善底质环境，提高饵料氮的利用率，但具体的生态学机制不清楚。针对多营养层次综合养殖池塘沉积物的氮迁出过程及其微生物驱动机制这一科学问题，本项目利用高通量测序技术系统地明确了池塘沉积物微生物菌群结构和多样性，沉积物细菌多样性和丰度高于水体，贝类能提高水体中异养和光养细菌丰度以及沉积物中异养细菌丰度；采用同位素示踪技术和定量PCR检测技术相结合的方法揭示了硝化、反硝化和厌氧氨氧化菌共同驱动的池塘沉积物氮迁出过程，发现养殖后期的贝类养殖区存在厌氧氨氧化反应，且反硝化、厌氧氨氧化反应速率与氨氮浓度显著正相关；发现池塘混养埋栖型贝类菲律宾蛤仔、缢蛏、硬壳蛤等均能显著增加沉积物表层AOB、nifH和nosZ等功能基因的丰度，加速沉积物/水界面的氮循环过程，阐明了贝类促进沉积物氮迁出的重要生态学作用机制；在此基础上耦合氮素营养动力学过程，基于Stella系统建立池塘多营养层次综合养殖系统氮迁出动力学模型，开发了应用软件。本项目研究成果一方面能够丰富水生态系统氮循环的基础理论，另一方面也为优化海水池塘多营养层次综合养殖系统提供了科学依据，进一步提高营养物质循环利用效率和减少氮磷排放，助力我国海水养殖产业绿色发展。研究过程中共发表研究论文9篇，其中SCI论文7篇（TOP期刊5篇），中文核心期刊2篇；参与编写专著2部；授权发明专利1件，申请软件著作权1件。