大亚湾浮游植物DNA指纹及其与群落结构的关系

于2012年5月、6月采集了大亚湾9个站点的表层水样,利用PCR-变性梯度凝胶电泳(PCR-DGGE)技术对浮游植物DNA指纹进行了分析,同时通过显微镜观察对浮游植物进行了定性定量分析.研究结果显示,大亚湾浮游植物种类丰富,共分析鉴定出浮游植物72种;浮游植物DNA指纹也较为丰富,2个月份指纹条带数分别为26条和28条.DGGE指纹条带数一般远远低于浮游植物种类数,在剔除了相对含量小于0.1%的非优势种后,DNA条带数与种类数变化趋势相近,说明DNA指纹图谱能较大程度地反映浮游植物优势种群的组成,而对于相对含量较少的物种,可能会由于优势种的屏蔽作用而被掩盖.DNA指纹图谱与浮游植物群落结构的聚类分析结果相近,富营养化的近岸站点聚在一起,而远岸站点聚为一类.虽然目前大亚湾浮游植物群落结构中以硅藻占据优势,但在某些站点大量出现的甲藻和蓝细菌值得进一步关注.本研究结果表明PCR-DGGE技术可在一定程度上运用于浮游植物群落结构分析.

The DNA fingerprints and their relationship to community structure of phytoplankton in Daya Bay

Surface water was collected from Daya Bay, South China Sea in May and June, 2012. The DNA fingerprints of phytoplankton extracted from these water samples were analyzed using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) technique; meanwhile the phytoplankton were examined and counted under light microscope. The results showed that the species richness of phytoplankton was high with a total of 72 species. The numbers of DNA fingerprint were also high with 26 and 28 in May and June, respectively. The fingerprint numbers were generally much lower than species richness; however, both showed similar variation pattern at different stations when excluding species with percentage less than 0.1%. This similarity indicates that the DNA fingerprints largely reflect the composition of dominant phytoplankton, which may have shielded the minority group during the PCR-DGGE process. Cluster analysis of DNA fingerprints and phytoplankton community similarly revealed a separation between the eutrophic, nearshore stations and those offshore stations. The phytoplankton community in the Daya Bay is dominated by diatoms, but attention should be paid to the abundant occurrences of potentially harmful species of dinoflagellate and cyanobacteria at some stations. This study demonstrates that the PCR-DGGE technique is applicable in analyzing phytoplankton community structure, though microscopic morphology still remains one of the most reliable methods.