冬季和春季长江口及其近海水域浮游病毒丰度的分析

VIRIOPLANKTON ABUNDANCE IN WINTER AND SPRING IN CHANGJIANG RIVER ESTUARY BY FLUORESCENCE MICROSCOPE COUNTING

采用荧光显微技术,对2006年长江口及近海水域20个站点的表层及10m层或潜水体冬、春两季的浮游病毒丰度进行了检测,对浮游病毒丰度在季节(冬、春两季)、水平分布和垂直分布上的变化进行了探讨。调查区浮游病毒丰度在冬、春季节上并无明显差异,但在水平分布上存在很大差异,河口区浮游病毒直接检测量(Virus Direct Count,VDC)达到107个/ml,近海水域VDC为106个/ml,河口区的浮游病毒丰度都明显高于近海水域病毒丰度(P<0.01)。在垂直分布上,冬、春两季长江口水域水深小于10m的站位,表层浮游病毒丰度与底层病毒丰度无明显差别,水深大于10m的站位,表层水样的浮游病毒丰度都高于10m水层病毒丰度,说明长江口浮游病毒的垂直分布与站位总水深有关。还通过比较各站点VDC与叶绿素a含量的数据,分析了二者之间的相关性:冬季浮游病毒丰度与叶绿素a含量成正相关性;春季浮游病毒丰度与叶绿素a含量成负相关性,但病毒丰度受叶绿素a含量的影响仅为10%—11%。

In most aquatic environments, virioplankton is the most abundant plankton class. Virioplankton promotes the release of dissolved organic material and the regeneration of inorganic nutrients. It plays an important part in influencing the size structure of community and the pathways of material and energy transport in marine ecosystem. To study the distribution and seasonal variation of virioplankton in Changjiang （Yangtze） River estuary, virioplankton abundance in February （winter） and May 2006 （spring） was studied in the estuary. In this study, virioplankon was quantified by using fluorescent microscope. The samples were collected using Rossette into 50ml sterilized vials, fixed by formaldehyde （3.5%, final concentration） and then stored at 4℃ for counting virioplankton. The data was analyzed with the statistic method of independent t-test and the unitary linear regression analysis. Result show that the range of virus abundance was 0.490-19.2 and 0.821-21.9 （×10^6 viruses/ml） in the winter and spring respectively. No significant seasonal but geographical variation in virioplankton abundance was found. Using virus direct count by fluorescent microscope to represent the abundance, we found that the virus count in the estuary was 10^7/ml significantly higher than that of in the offshore area at 10^6/ml （P 〈 0.01）, due probably to that nutrient concentrations in the estuary were much higher than that in the offshore area. In vertical direction, the distribution of the viral abundance varied with the site depth. In shallow water （〈10-m depth） areas, no significant change in virus concentration was found, whereas in deeper regions （〉10-m depth）, the virus concentration decrease with depth. In season, virioplankton abundance was positively in winter but negatively in spring correlated with chlorophyll a concentration significantly （P 〈 0.05）.