华南沿海甲藻孢囊生物多样性与地理分布研究

Cyst is the resting stage of many dinoflagellates. Dinocysts are regarded as the seed bed of algal blooms, and also the carrier for the worldwide expansion of harmful dinoflagellates. However, There are many uncertainties about the dinocyst species richness and the relationships between cysts and vegetative cells, and less information about biodiversity and geological distribution of dinocysts in Chinese coastal waters. In this project, we will choose the Southern Chinese coasts as studying area. Surface sediments will be collected, and dinocysts will be analyzed morphologically and by rDNA sequences to understand the biodiversity and geological distribution of dinocysts, and to establish the atlas of dinocysts. The sediments will be germinated directly to highlight the potential of harmful algal blooms. The relationships between cysts and vegetative cells will be discovered through a series of studies such as sediment and cyst germination, single cell PCR-rDNA sequencing of cysts and vegetative cells. Meanwhile, the information about cyst-forming dinoflagellates will be enriched, and their geological regions will be understood. The DNA finger prints of cyst will be studied by PCR-DGGE technique. High-throughput sequencing will be used to enrich the biological and molecular diversity of cyst, and a DNA data base of cyst will be established. The results of this project will provide a comprehensive knowledge about biodiversity and geological distribution of dinocysts, and give an important guidance in bloom prevention and prediction in the Southern Chinese coasts.

孢囊是许多甲藻的重要休眠时期，被认为是赤潮发生的种源，也是有毒有害甲藻全球扩展的载体。但目前对于孢囊生物多样性以及孢囊与营养细胞的对应关系了解尚不充分，而我国沿海孢囊生物多样性和地理分布信息则更为有限。本项目拟以华南沿海为研究重点，对甲藻孢囊进行分类学研究，建立孢囊图谱，丰富孢囊生物多样性，揭示其地理分布规律；对沉积物进行直接萌发，揭示有毒有害赤潮发生的潜在风险；通过沉积物直接萌发、孢囊萌发以及孢囊与营养细胞单细胞PCR-rDNA序列测定，明确孢囊与营养细胞的对应关系，丰富产孢囊甲藻信息，揭示其地理来源；利用PCR-DGGE技术对孢囊进行DNA指纹分析，并通过切胶测序以及高通量测序，丰富孢囊物种多样性和分子多样性，建立DNA数据库。项目实施将全面揭示华南沿海孢囊生物多样性和地理分布信息，对华南沿海有毒有害赤潮的预防、预警具有重要指导意义。

采集了华南沿海17个海域的表层沉积物样品，对沉积物中甲藻孢囊进行分类学研究，共鉴定甲藻孢囊57种，建立了孢囊图谱，丰富了华南沿海甲藻孢囊的多样性。绘制了34种孢囊在中国沿海的地理分布图，填补了甲藻孢囊在我国沿海地理分布信息。结果显示锥状斯氏藻是我国沿海最为常见的孢囊类型，有毒有害赤潮原因种塔玛亚历山大藻和链状裸甲藻的孢囊分布广泛，珠江口海域和北海港为有毒有害赤潮藻孢囊高值区，具有赤潮爆发的潜在风险。华南沿海沉积物中较低的甲藻孢囊密度以及较高的异养型甲藻孢囊百分比含量是工业污染、富营养化以及港口水体扰动的标志；生物硅和Cd是影响广东沿海孢囊分布的重要因素，TN对广西沿海孢囊分布影响明显，而盐度则对海南西北沿海孢囊分布影响较大。锥状斯氏藻孢囊可作为盐度、富营养化以及水环境变化的有效指示种，可指示多种人类活动干扰的环境变化。对沉积物中总DNA进行了提取，对18S rDNA V4区进行了基因组测序，共得到真核藻类156973个序列，218个不同的OTUs，鉴定到种的真核藻类共75种，其中中国沿海新记录中5种。甲藻种类多样性和数量均最为丰富，从甲藻DNA序列数的地理分布来看，可以发现有两个甲藻孢囊热点，一个是以环北部湾的粤西和广西沿海，优势种类为小型薄壁甲藻Biecheleria，该藻也萌发的浮游植物中大量出现，具有潜在赤潮风险。另外一个高值区位于红海湾以及粤中海域，优势种类为裸甲藻Gymnodinium aureolum。通过形态学分析、单孢囊PCR和孢囊萌发，建立了重要有毒有害甲藻营养细胞及其孢囊的对应关系，分析它们的地理来源，发现多与东亚其他海域如日本、韩国海域株系同源性较高。本项目研究结果全面揭示华南沿海孢囊生物多样性和地理分布信息，对华南沿海有毒有害赤潮的预防、预警具有重要指导意义。项目共发表了学术论文18篇，其中SCI 收录论文8篇。培养博士、硕士研究生8名。参加国际学术会议6人次，组织国外专家访学交流4人次。