我国典型热带海域底栖甲藻的生物多样性及其时空分布研究

Benthic dinoflagellates are widely distributed in tropical and subtropical seas. They functioned a very important role in the marine benthic food chains. Harmful events associated with benthic dinoflagellates, have been reported more frequently over the last decade including in areas where those benthic genera were hardly known. Of particular concern are the outbreaks of toxic dinoflagellate blooms which associated to the ciguatera fish poisoning (CFP). The ciguatoxins produced by Gambierdiscus are bioaccumulated in reef fishes and are responsible for the most common algal toxin-related illnesses, globally affecting the greatest number of victims and often with significant long-term health effects. Because benthic dinoflagellates, have not been extensively investigated worldwide. The degree to which various environmental factors control the distribution and abundance of individual dinoflagellate populations is largely unknown and would be a major focus on the study. The benthic dinoflagellates have rarely been studied in China. Hainan Island is a typical tropical island with rich substrates for benthic dinoflagelles growth. We propose to study the biodiversity, temporal and spatial distribution of benthic dinoflagellates in Hainan Island. The objective for the project are to answer the following scientific questions. How many species are in the area(biodiversity)? What are the environmental parameters that affect the local distribution and abundance of benthic dinoflagellates? What are the main ecological interactions(substrate specificity, trophic links, competition) related to benthic dinoflagellates? Through this study, we try to identify the important physical and chemical factors that control abundance and distribution over the temporal and spatial scales, and to determine the primary physiological, genetic, environmental processes that regulate population growth.

海洋底栖甲藻是广泛分布于热带、亚热带的一类附着藻类，在海洋底栖食物链中扮演着重要角色。很多底栖甲藻具有毒性或潜在毒性，通过食物链传递对海洋鱼类及人类健康构成严重威胁。底栖甲藻不同种类不同地理株系在形态结构和对环境因子的响应差异较大，同时也影响底栖甲藻的时空分布。有关我国热带海域底栖甲藻的研究很少，本项目拟通过普通光学显微镜、荧光显微镜和电子扫描电镜对采自海南岛海域底栖甲藻进行系统的分类学研究，了解底栖甲藻的种类多样性；通过生态学研究，阐明底栖甲藻的时空分布特征；借助分子生物学技术对优势种群进行系统发育学分析，确定其在分类学上的准确地位和生物地理分布格局；通过现场和实验室研究，分析影响底栖甲藻生长与分布的关键环境因子。本研究结果将为更全面了解我国海洋藻类生物多样性提供依据，为我国海洋底栖甲藻的进一步研究提供参考，同时为底栖甲藻藻华的防灾减灾提供科学依据。

本研究选取我国典型热带和亚热带海岛——海南岛为研究对象，在海南岛周边共设立6个采样点，在不同季节分4次进行潮下带取样，通过对采集得到的大量大型藻、死珊瑚等基质上底栖甲藻样品的采集、分离和纯化，获得海南底栖甲藻藻种，利用形态学和分子生物学技术对培养的藻株进行鉴定和系统分析，确定其在分类学上的准确地位和生物多样性。.通过研究，得到以下结果：.1. 共鉴定出18种底栖甲藻，隶属于Prorocentrum，Gambierdiscus，Ostreopsis，Coolia，Amphidinium及Sinophysis 6个属，其中P.concavum，P. fukuyoi，P.emarginatum，G.caribaeus，G. pacificus，G. australes，O.ovata，O. lenticularis，C. malayensis，C. tropicalis，C. canariensis，A.operculatum，A. massartii和A. gibbosum等14个种为中国的新记录种，另外4个种分别是P. lima，P. rhathymum，A. carterae和S. microcephala。.2.对中国海南的利马原甲藻（P. lima）进行了种下分类，共鉴定出6个P. lima变型。系统发育分析的结果与形态鉴定的结果在种水平上一致。.3. Prorocentrum属是海南底栖甲藻中的优势类群，在多个站点细胞数量占总细胞数量的比例超过50%，最高细胞密度达到2704 cells/g macrophyte其它属的细胞密度较低，低于400 cells/g macrophyte。.4. 相关性分析表明底栖甲藻总细胞密度与水温和采样深度成负相关，与盐度成正相关。