淡水原生动物群落构建与演替规律及其对水产养殖的意义

Protozoa in the aquatic ecosystem link different trophic levels together through saprophytic and/or predatory chains, they play important roles in the biogeochemical cycling of carbon (C), nitrogen (N) and phosphorus (P), and are also of great importance to energy flow. Therefore, the protozoa community as a whole makes significant contribution to the primary production and natural purification in aquatic ecosystem, which further provides ecosystem service for aquaculture. However, most studies of protozoa taxonomy and ecology have been restricted to morphological identification, which has historically been a difficult task (even for seasoned taxonomists) due to the lack of distinguishing features for many of these small eukaryotes. Therefore, the methods available have greatly restricted large scale and systematic study to understand the spatiotemporal turnover and some other related ecological functions of protozoa community. Accompanying the extend of metagenomic analysis to the natural communities of bacteria and fungi from various types of environments; we explored the possibility of applying high-throughput sequencing analysis for studying the eukaryotic protozoa communities collected from different environments. Targeting the fresh water bodies for aquaculture, which directly affected by the human activities, this proposal will focus on the following three tasks: i) uncover the mechanisms that govern the phylogenetic diversity of protozoa communities in different water bodies that used for aquaculture; ii) elucidate the relationships between protozoa and fishes in particular water bodies, and reveal their mutual responses to each other; iii) how the protozoa community contribute to aquaculture and how it reflect the water environments. The goal of this study is to reveal the assembly and turnover of freshwater protozoa communities and its ecological significances for aquaculture. All of these works will not only strength our understanding of ecological functions of protozoa community in the fresh water bodies for aquaculture, but will also provide us necessary biological evidences for healthy and sustainable development of water environments that used for aquaculture. In a word, this study is of great importance for both academic study and practical application.

原生动物在水体生态系统中通过捕食链和腐生链参与碳、氮、磷等关键生源要素循环和能量流动，从而对水体初级生产、环境自净和水产养殖等具有重要的意义。然而，原生动物分类和生态研究一直都受形态鉴定制约，使得大规模、系统性研究其时空演替规律及相关生态功能受到了一定限制。伴随着针对细菌、真菌等微生物群落宏基因组研究的推广，我们探讨了对不同环境原生动物群落进行高通量测序分析，结果证明是切实可行的。本课题以淡水养殖水体这一受人类生产活动直接影响的生态系统为对象，围绕不同养殖水体原生动物群落系统发育多样性的形成和维持机制、原生动物与养殖鱼类的相互关联和影响机制、以及原生动物对水产养殖的贡献和环境预警作用开展研究，重点阐述原生动物群落构建和演替规律及其对水产养殖的生态学意义。这不仅能增强我们对淡水养殖水体原生动物生态功能的认识，而且也可为养殖水环境的健康和可持续发展提供科学依据，具有重要理论研究和实际应用价值。

原生生物和细菌等微生物在养殖生态系统碳、氮、硫等关键生源要素循环和能量流动中发挥着重要作用，因此与养殖系统初级生产力、营养循环及养殖对象健康等紧密相关。然而，养殖系统原生生物群落多样性和功能与细菌的互作机制，以及它们与生态和环境因子的耦联机制仍不清楚。本项目以养殖池塘这一受人类生产活动直接影响的生态系统为对象，围绕不同规格鱼虾（如草鱼、对虾）养殖池塘原生生物和细菌等群落多样性的形成和维持机制，原生生物和细菌与养殖鱼虾的相互关联和影响机制，以及原生生物和细菌群落、硫酸盐还原和硫氧化等功能菌群对水产养殖的贡献开展研究，以期揭示养殖池塘原生生物和细菌等群落构建及演替规律，进而阐明原生生物和细菌群落与养殖环境的关系及其对水产养殖的意义。研究结果表明，养殖鱼类对底泥的扰动主要通过增强环境均质选择和减弱水体和底泥的扩散限制而影响池塘原生生物群落多样性和结构；对虾养殖过程中，氮负荷增加导致绿藻丰度下降，并通过增强环境均质选择而驱动原生生物群落演替；绿藻和真菌分别是养殖水体和底泥中微型真核生物-细菌互作网络中优势主导种类，微型真核生物和广布种对微生物互作网络稳定很重要；硫化合物和鱼类扰动引起的底泥悬浮是导致养殖池塘沉积物中硫循环微生物多样性和群落结构变化的主要影响因素。相关研究结果已发表标注资助SCI论文14篇（其中4篇中科院大类一区，7篇二区）；培养出站博士后1名、培养研究生6名（已毕业博士生2名、硕士生4名），超额完成了目标任务。本项目不仅阐明了养殖池塘原生生物和细菌多样性、群落构建及与细菌互作机制，而且拓展了对水产养殖系统微生物驱动硫循环及环境调控机理的认知，为养殖池塘关键元素的物质循环通路提供理论依据，也将为绿色养殖和管理提供参考。