Characteristics of eukaryotic microalgal community and its abiotic influencing factors during brown tide blooms near Qinhuangdao, China.

The brown tides caused by the picoplanktonic pelagophyte Aureococcus anophagefferens in the coastal waters of Qinhuangdao, China have occurred periodically since 2009 and exerted deleterious effects on scallop cultivation in the area. In this study, clone libraries were constructed to determine the characteristics of the local eukaryotic microalgae community, and a real-time fluorescent quantitative PCR assay was performed to analyze the temporal and spatial variations in the 18S rDNA copies of A. anophagefferens samples collected in 2012. The results showed that A. anophagefferens was the dominant species in the local eukaryotic microalgae community during the brown tide in June 2012 and accounted for a large fraction of the community. A redundancy analysis (RDA) showed that the decreasing concentration of dissolved inorganic nitrogen (DIN), increasing amount of human aquaculture activities and suitability of spring/summer temperatures for the growth of A. anophagefferens may be the primary causes of the brown tide outbreaks in the Qinghuangdao scallop culture area.