黄海沉积物中纤毛虫生物多样性与分布特征

Ciliates are a morphologically high diverse and ecologically important group of protozoa in sediments of shallow seas and have been considered as model organisms in evaluating microbial biodiversity and biogeography. So far our knowledge of ciliate diversity in marine sediments is largely restricted to that from intertidal zone. Due to technical and taxonomic impediments, the species composition, diversity and distribution of ciliates in marine sediments, in particular those in offshore areas are largely not known. In this project, with direct isolation of ciliates from marine sediments, we intend to establish successive and diversified cultivations by incubating sediment samples under a variety of conditions to stimulate the growth of rare and encysted ciliates. By using modern taxonomic techniques, the Ludox centrifugation combined with quantitative protargol stain (Ludox-QPS), and the high-throughput sequencing of 18S rDNA in combination with the FISH-SEM method, we aim to (i) uncover the species and molecular diversity of ciliates in offshore sediments of the Yellow Sea; (ii) discover new and cryptic species of ciliates; (iii) elucidate the diversity and distribution of ciliates along with benthic environmental factors; and (iv) estimate the species-abundance relationship and the potential species diversity of benthic ciliates in the Yellow Sea. This study will be the first combined utilization of newly developed methods to uncover the hidden diversity of marine benthic ciliates. The project will supply the first-hand data to ciliate diversity in shallow sea sediments and lead the way to deep-sea research on ciliate diversity.

纤毛虫是近海沉积物中多样高且重要的原生动物类群，是揭示微型生物多样性和地理分布的模式生物。迄今对海洋沉积物中纤毛虫多样性的认识主要来自潮间带。由于技术局限和研究欠缺，对于近海，尤其是离岸海域沉积物中纤毛虫的分类构成、多样性及分布特点尚缺基本了解。本研究拟选择黄海这一典型海域，通过对沉积物多生境条件的建立和培养，在传统分类学基础上，通过对沉积物中纤毛虫的定量提取与定性分析，结合18S rDNA高通量测序及荧光标记-电镜观察(FISH-SEM) 这一新方法，搞清黄海沉积物中纤毛虫的物种及分子多样性构成，揭示新物种和隐存多样性；阐明纤毛虫随环境和地理距离的多样性构成及分布特点；厘清纤毛虫的物种-丰度关系，估计黄海沉积物中纤毛虫的潜在物种多样性。本研究系新技术方法在底栖纤毛虫多样性研究中的应用，将为近海底栖纤毛虫多样性研究提供一份翔实可靠的本底资料，为未来深远海相关研究提供一份可资借鉴的工作示范。

纤毛虫是沉积物中多样高且功能重要的原生动物类群，是揭示微型生物多样性和地理分布的扳机和模式生物。迄今对海洋沉积物中纤毛虫多样性的认识主要来自潮间带，对于陆架海域沉积物中纤毛虫生物多样性及分布特点尚缺认知。本研究通过定量提取与定性分析，结合18S rDNA和cDNA高通量测序技术，解析了黄海沉积物中纤毛虫生物多样性构成及分布特点，发现了新物种和隐存多样性及系统地位，揭示了纤毛虫随环境和地理距离的多样性构成与分布特点及物种-丰度关系。主要发现包括：（1）发现8新种，发表新物种3个，首次获得了伪角毛虫属模式种红色伪角毛虫的DNA序列并明确了其系统地位，确定了拟红色伪角毛虫的有效性，厘清了拟红色伪角毛虫和肉色伪角毛虫长期以来的混乱，构建了125种纤毛虫和1250条DNA序列的信息库；（2）发现黄海底栖纤毛虫物种-丰度间极显著正相关关系，基于分选鉴定的216种底栖纤毛虫的ICE分析，估计其潜在物种数达276种，而基于高通量测序及ICE分析潜在纤毛虫OTUs达944个，表明沉积物中纤毛虫多样性被大大低估了；（3）发现随着水深增大，黄海底栖纤毛虫丰度、生物量以及物种数降低，但陆架海区纤毛虫总物种数显著高于潮间带，南黄海纤毛虫群落与西太平洋深海及冲深海槽热液区差异显著，且多样性高于上述生境；（4）发现南北黄海的纤毛虫物种数、丰度和生物量的季节变化特点，夏季南北黄海纤毛虫未见显著差异，但冷水团内显著低于冷水团外；秋季南黄海则显著高于北黄海，而冷水团内外则未见显著差异；这些参数与底层水温度和沉积物中值粒径呈显著正相关。研究成果累计发表基金标注论文15篇，含SCI收录10篇；培养博硕士研究生6名。本项目首次比较分析了黄海沉积物中纤毛虫的物种和分子多样性及其分布特点，估计了黄海沉积物中纤毛虫的潜在生物多样性，为近海底栖纤毛虫多样性及分布提供了翔实可靠的本底资料，为深远海研究提供了一份可资借鉴的示范。