大型海藻上植表生硅藻的多样性与生态作用研究

Epiphytic diatoms are very common living on seaweeds in nature, and they may play significant roles in coastal waters due to their high species diversity, high biomass and high productivity. Epiphytic diatoms may have special and complicated ecological relationship with their host seaweeds and potential negative effect on economical seaweeds. However, little attention has been paid to this special diatom group. The taxonomy of epiphytic diatoms and their ecological importance keep poorly known and have not been comprehensively investigated in China seas. In this project, common seaweed samples will be collected seasonally or monthly from different waters of China seas. Morphological observation and species identification will be made with light microscopy and electron microscopy (SEM and TEM) to study the morphological characteristics, species composition, attached forms, and ecological characteristics of epiphytic diatoms on seaweeds. The biodiversity and ecological distribution of epiphytic diatoms in coastal waters of China will be investigated. The growth and epiphytism characteristics of epiphytic diatoms, and the relationship between epiphytic diatoms and seaweeds and its potential ecological mechanism will be studied with different culture experiments in laboratory. The morphological description and photograph of each species, and a taxonomic list of marine epiphytic diatoms in China will be given. This project will contribute to the taxonomic studies of marine diatoms in China and increase our insight into the potential ecological mechanism of epiphytic diatoms with their host seaweeds, which is essential and significant for marine ecology and seaweed aquaculture study.

在大型海藻上附生生活的硅藻为植表生硅藻，因其多样性和生产力高而可能成为近岸水域潜在的重要生产者，同时它们与大型海藻之间可能存在复杂多样的生态关系，对养殖海藻也存在潜在影响，但这一特殊的生物类群至今却很少受到关注，对其种类多样性和生态作用知之甚少。本项目拟采集我国常见大型海藻样品，利用光镜和电镜对海藻上的植表生硅藻进行形态学观察和系统的分类学研究，阐明我国大型海藻植表生硅藻的种类组成、形态特征、附生模式、地理分布和季节分布特点，获得其种类名录；分离培养植表生硅藻，研究其附生特性及其与大型海藻之间的相互作用和关系，探讨其特有的生态关系模式和机制。本研究将丰富我国海洋硅藻种类多样性信息，有望发现硅藻新种和/或新记录种，也有助于进一步揭示硅藻和大型海藻的附生关系在海洋生态系统中的重要作用和生态学机制及对养殖海藻的影响，具有重要的理论和实际意义。

在大型海藻上附生生活的硅藻为植表生硅藻，是表生硅藻的一个重要类群，不仅种类丰富，而且生物量和光合作用对初级生产的贡献很大，与宿主之间存在着复杂的生态关系，但这个特殊类群的硅藻在各类研究中普遍被忽略，尤其是针对我国海藻上植表生硅藻的分类学与多样性缺少系统的研究报道。针对这一问题，本项目对我国各海区大型海藻上的植表生硅藻进行了系统的物种多样性和分类学研究，共采集大型海藻样品293份，通过光学和电子显微镜观察，鉴定到了我国近海常见大型海藻上植表生硅藻2纲10目21科78属183种，其中海生双眉藻属（Halamphora）的分类单位最多，共21种；对植表生硅藻种类进行了形态特征、附生形式、生态分布特征描述并提供了种类名录和图谱；发现并描述了2个硅藻新种，1个我国新记录硅藻属和19个我国新记录种；确定了大型海藻上植表生硅藻的典型种类7属8种。通过观察发现植表生硅藻的种类多样性与宿主海藻的种类和形态结构有关；大部分植表生硅藻在不同种类的海藻上均可以生活，部分植表生硅藻有一定的宿主偏好性。影响筼筜湖大型海藻上植表生硅藻群落的主要环境因子在春季为温度，在夏季为pH值，在秋季和冬季为盐度。植表生硅藻与宿主大型海藻的室内共培养结果表明，不同大型海藻均能抑制硅藻的生长，不同浓度的硅藻对大型海藻的影响不同，初步揭示了二者间的生态关系模式。本研究丰富了我国海洋硅藻分类学研究内容和区系信息，为阐明海洋硅藻和大型海藻之间复杂多样的关系提供了新的思路和证据，有助于进一步揭示硅藻在海洋生态系统中的重要作用和生态学机制，对海洋生物学和海洋生态学及海藻养殖研究具有重要的理论和实际意义。