渤海长兴岛海域微型和微微型浮游植物多样性

Diversity of Marine Nanophytoplankton and Picophytoplankton in Changxing Island Offshore Waters of Bohai Sea

为研究微型/微微型浮游植物在褐潮生消过程的多样性变化,以18S r DNA V4区作为目标基因,结合高通量测序技术,对2014年5月、7月和2015年5月、7月长兴岛近岸海域海水中微型/微微型浮游植物多样性进行了检测.结果表明,高通量测序技术可有效地检测长兴岛近岸海域海水中微型/微微型浮游植物多样性,自行设计的V4(F/R)引物在微型/微微型浮游植物群落鉴定方面更为高效.2014年5月、7月在长兴岛海域分别检出微型/微微型浮游植物143、165种,2015年5月、7月分别检出123、167种.微型/微微型浮游植物群落中绿藻门相对丰度最高,2014年5月、7月分别为44.5%、65.6%,2015年5月、7月分别为81.8%、73.7%.微型/微微型浮游植物多样性指数和种类数都是同年7月高于5月,说明7月海水中微型/微微型浮游植物群落结构较5月稳定.同时发现了渤海海域的褐潮致灾种微拟球藻(Nannochloris sp.)和金牛微球藻(Ostreococcus tauri),2014年和2015年其平均优势度分别为0.37和0.39;而已发现的褐潮致灾种——抑食金球藻(Aureococcus anophagefferens)在长兴岛海域的4次调查中虽都有检出,但其优势度(平均为0.000 3)较低.

To determine nano- and picophytoplankton diversity in brown tide outbreaks and degradation,offshore waters from Changxing Island,where a brown tide occurred in 2013,were analyzed by high-throughput sequencing with the 18 S r DNA V4 region as the target gene. The results revealed that high-throughput sequencing technique effectively explored nano- and picophytoplankton diversity,and the primer V4（ F/R） could successfully identify nano- and picophytoplankton. At the species level,two samples contained 143 and 165 nanoand picophytoplankton species in May and July 2014,respectively. The other two samples had 123 and 167 species in May and July2015,respectively. Chlorophyta was the predominant phyla in all four samples,accounting for 44. 5%,65. 6%,81. 8% and 73. 7%.Nano- and picophytoplankton diversity was higher in July than in May,suggesting that the community structure was stable in July. The predominant species were Ostreococcus tauri and Nannochloris sp.,with an average degree of dominance of 0. 37 and 0. 39 in 2014 and2015,respectively. The brown tide algae Aureococcus anophagefferens was found in four samples,but was not the predominant species. Its average degree of dominance was 0. 0003 in 2014 and 2015. Therefore,nano- and picophytoplankton diversity was lower in brown tide outbreaks,but the relative abundance of dominant species was higher.