于1994～1998年期间调查了浮游植物生产的生源气候气体二甲基硫（DMS）及其前身二甲基硫丙酸（DMSPp）在我国胶州湾、芝罘湾、东海的分布状况及其影响因素。结果表明，自然海区中二者浓度都存在明显的时空变化。地理分布规律是，高值出现在沿岸海区和陆架海区，低值出现在外海特别是贫营养海区。就不同季节而言，高值出现在春季或夏季，低值出现在秋季。DMS或DMSPp的分布在大尺度上主要受海流和水团的影响，而在小尺度上营养条件和生物因子则更重要。 在近岸海区，硅藻是DMS和 DMSPp的重要贡献者。研究海区硝酸盐与DMSPp的关系有两种情况：当硝酸盐浓度低于1μmol/L时，二者为正相关，硝酸盐浓度高于这个阈值时，二者为负相关。表明浮游植物细胞中二甲基硫丙酸作为渗透压调节物质其含量受到氮源可得性的调控。此外，研究结果还显示，生活污水入海、海水养殖等也对DMS和DMSPp的浓度分布有一定影响。

Aims: To examine the community structure of cyanobacterial populations of the South China Sea on the surface and at depth of 80 m. Methods and Results: Direct PCR amplification of RNA polymerase (rpoC1) genes from environmental DNAs extracted from seawater, and cloning of the fragments and sequence analysis were used. A great diversity of Prochlorococcus and ynechococcus were detected at the investigation site. Genetically related Prochlorococcus were found in both layers while Synechococcus were found only on the surface. Prochlorococcus were clustered with the known high-light adapted II genotypes, and further divided into seven groups. Synechococcus could be divided into two groups, and the second group could be further subdivided into several clades. Conclusion: The dominant genotype of Prochlorococcus was high-light adapted II genotype, and Synechococcus were distributed basically on the surface. Significance and Impact of the Study: This is the first report about the cyanobacterial community structure in the South China Sea, and an important supplement to the current understanding of the relationship between genetic and ecological diversity and environments.

Aerobic anoxygenic phototrophic bacteria (AAPB) are characterized by the following hysiological and ecological features. A mother AAPB cell can unusually divide into 3 daughter cells and looks like a "Y" during the division. AAPB cells sometimes adhere together forming a free-floating population. Most of the known AAPB species are obligately aerobic. Bacteriochlorophyll a (BChl a) is the only photosynthetic pigment in AAPB, and the number of BChl a molecules in an AAPB cell is much less than that in an anaerobic phototrophic bacterial cell, while the accessorial pigments carotenoids in AAPB are abundant in concentration and diverse in species. In addition to the common magnesium containing BChl a, a zinc-containing BChla was also seen in AAPB. AAPB have light harvesting complex but usually lack light harvesting complex. Although AAPB featur in photosynthesis, their growth is not necessarily lightdependent. There is a mechanism controlling the photosynthesis approach. AAPB are widely distributed in marine environments especially in oligotrophic oceans accounting for a substantial portion of the total biomass and playing a unique role in the cycle of carbon and other biogenic elements. Besides the contribution to primary production, AAPB also have great potentials in bioremediation of polluted environments. Studies on AAPB would be of great value in understanding the evolution of photosynthesis and the structure and function of marine ecosystems.

Accurate quantification of aerobic anoxygenic phototrophic bacteria (AAPB) is of crucial importance for estimation of the role of AAPB in the carbon cycling in marine ecosystems. The normally used method "epifluo-rescence microscope-infrared photography (EFM-IRP)" is, however, subject to positive errors introduced by mis-taking cyanobacteria as AAPB due to the visibility of cyanobacteria under infrared photographic conditions for AAPB. This error could be up to 30% in the coast of the East China Sea. Such bias should be avoided by either ubtracting cyanobacteira from the total infrared counts or using a flowcytometer equipped with specific detectors for discrimination between cyanobacteria and AAPB.