东海底栖纤毛虫多样性分布格局与驱动因素

Ciliates have been regarded as a target group in evaluating the key issues of microbial eukaryotic biodiversity and biogeography. Marine benthic ciliates, being their high diversity and strong assiciation with sediments, might be the answer of these hot issues. The East China Sea (ECS) represents an ecoystem with diverse habitats and complex fauna. However, little is known on the diversity and distribution of benthic ciliates in the ECS. In this project, we aim at answering the following scientific questiones: Do benthic ciliates in the ECS exist a latitudinal diversity gradient like that of macrofauna? Is the diversity and distribution pattern of benthic ciliates in the ECS similar to that of benthic ciliates in the Yellow Sea or that of meiofauna in the ECS? What are the main factors regulating their diversity and distribution pattern? By combining the morphological methods (including living obsvervation, silver stain and the Ludox-QPS) and high-throughput DNA and cDNA sequencing of 18S rRNA gene, we will evaluate the species richness and the biodiversity and distribution pattern of benthic ciliates in the ECS and elucidate the main driving factors. Meanwhile, third-generation sequencing will be developed for evaluating the marine ciliate diversity as well as other microeukaryotes in sediments. This study aims to provide reliable and detailed data for estimation of the benthic ciliate diversity and driving factors in the ECS. The project will also supply a sample research protocol for studying the microeukaryotic diversity in marine sediments.

纤毛虫是探讨真核微型生物多样性和地理分布热点问题的靶标生物，海洋底栖纤毛虫因其高多样性及与沉积物的高关联度而成为探讨该问题的一个潜在突破口。东海是生境多样、区系复杂的生态系统，有关该海域的底栖纤毛虫尚缺基本认知，并存在如下待解的问题：东海底栖纤毛虫是否具有类似大型生物的多样性纬向分布格局？是具有类似黄海的纤毛虫多样性分布特点，还是类似东海的小型底栖动物分布特点？驱动其多样性分布格局的主要因子是什么？本项目拟针对上述科学问题，在传统分类学基础上，通过Ludox-QPS法定量与定性研究，结合18S rRNA基因的DNA和cDNA高通量测序分析，并开发利用三代测序技术，全面评估东海底栖纤毛虫的多样性及分布格局，阐释驱动其多样性格局的主要因素。本研究将为东海底栖纤毛虫多样性提供可靠的本底资料，为阐释纤毛虫多样性分布格局提供切实依据，为开展海洋沉积物中真核微生物多样性研究提供可资借鉴的方案。

本项目通过分类学与分子系统发育分析，并结合Ludox-QPS法定量定性技术与高通量测序分析，研究了东海底栖纤毛虫多样性与分布格局及主要驱动因素。主要成果包括：1）清理了伪角毛虫属的分类误识，发现红色伪角毛虫一新种，厘清了伪角毛虫相关三亚科和突口虫科的系统关系；2）确定水深、底层水温及盐度是控制东海底栖纤毛虫群落的主要因素；建立了标本库、DNA库和序列库；3）发现东海不同于黄海和南海的纤毛虫群落结构，发现在多样性上东海最低，黄海最高，其次为南海这一不同于中国近海大型底栖生物的纬度梯度分布模式；4）完善了二代高通量分析流程，建立了三代高通量技术体系，厘清了单细胞内18S rDNA变异、水体DNA沉降、DNA/RNA提取及处理对底栖纤毛虫多样性评估的影响。项目出版专著1部，发表论文14篇，含SCI收录8篇，投出审理多篇；培养研究生3名，核心成员入选2022年中国科学院青年创新促进会。主编的《<海错图>通考》被国家海洋局等五部局推选为2022年国家级优秀海洋图书，被中国海洋学会推选为2022年度海洋优秀科技图书。参与主持制定国际标准《海洋环境影响评估（MEIA）-海底区海洋沉积物调查规范-间隙生物调查》，入选2021年度中国十大海洋科技进展、中国海洋与湖沼十大科技进展。