胶州湾浮游病毒的分布研究

Distribution of virioplankton in the Jiaozhou Bay

运用荧光显微镜技术,对2007年6～8月胶州湾14个站点的浮游病毒丰度进行了检测,分析了病毒在不同月份的水平与垂直分布变化,发现胶州湾浮游病毒的丰度在0.48×107～22.78×107个/mL之间,平均值为(5.72±4.72)×107个/mL,7月份病毒丰度明显高于其他两个月(P<0.01)。病毒呈现从湾内至湾口至湾外递减的趋势,病毒垂直分布变化不明显。病毒-细菌比率(VBR)范围为3.90～150.72,平均值42.05±28.55,处于较高水平。利用多元相关性分析发现,病毒丰度与异养细菌丰度、聚球藻蓝细菌丰度和叶绿素a含量相关,其相关系数r分别为0.605(P<0.01),0.265(P<0.01)和0.604(P<0.05),确定系数R2分析表明,异养细菌和叶绿素a对浮游病毒丰度的影响基本相当。病毒丰度与温度、盐度无明显相关性。对VBR的分析表明,调查区域藻类病毒占总浮游病毒的比例较高;通过VBR与异养细菌丰度的负相关性分析,认为胶州湾噬菌体的宿主菌种群较单一。

To study the distribution of virioplankton in the Jiaozhou Bay, three cruises were performed in June, July, and August 2007. Virioplankton abundance was determined by epifluorescence microscopy. Direct count of virus in the Jiaozhou Bay was ranging from 0.48×107 particles/mL to 22.78×107 particles/mL for all sample stations in three cruises, averaging 5.72×107±4.72 ×107 particles/mL. The abundance of virioplankton in July was significantly higher than those in June and August （P〈0.01）. Virioplankton abundance was higher in offshore waters, and decreased toward the open sea. There was no obvious pattern of vertical distribution of virioplankton. The Virus- to-Bacteria Ratio （VBR） ranged from 3.90 to 150.72, with an average of 42.05±28.55. According to multi-correlation analysis, virioplankton abundance was positively correlated with heterotrophic bacteria abundance （r= 0.605, P〈0.01）, Synechococcus abundance （r= 0.265, P〈0.05） and Chlorophyll a concentration （r= 0.604, P〈0.01）. No significant correlations were found between virioplankton abundance and temperature and salinity. High VBR suggested a high portion of algal virus. VBR was negatively correlated with heterotrophic bacteria abundance （P〈0.01）, indicating relatively limited host species for phages.