Variability of bacterioplankton in the north zone of Lake Taihu

2003年1月-12月对太湖北部湖区8个采样点进行了每月1次、为期一年的水体中浮游细菌数量的测定,并同步对溶解性有机碳(DOC),总氮,总磷,叶绿素a和温度进行了测定,结果表明:浮游细菌数量存在明显的季前变化和空间差异,夏秋季浮游细菌数量比冬春季高,最高值出现在夏季的7月份,平均值为7.43×106cell/ml,最低值出现在3月份,平均值为3.14×106cells/ml,最低值与最高值差异达73%;污染严重的河口区浮游细菌数量明显高于湖心区,最高值出现在河口的6#点,平均值为5.51×106cells/ml,比湖心区最低值8#点高83.2%,并呈现从河口、湾内至湖心随水体污染程度减轻而逐步递减的趋势;浮游细菌数量与温度和浮游植物量显著相关.而与水体中营养盐无关,预示着太湖水体中的营养盐已处于较高的水平,不再是浮游细菌生长的限制因素,而来源于浮游植物的有机碳可能是其生长的重要碳源.;Bacterioplankton are not only decomposers of organic material but also secondary procurers in water ecosystems. They are abundant and dynamic members of remobilizalion of organic carbon and regeneration of inorganir nutrients in water environments. This paper presents the seasonal variation in the abundance of bacteri op lank loti and the difference in different zone, the relationship between the environmental fadors and ihe abundance of bacte-rioplankton in ihe North Lake Taihu from January to December in 2003, the results showed that the numher of bacte-rioplankton changes with the seasons. With the increase of water temperature, the number of bacterioplanklon in the water increases, the smallest value in winter,and the largest value in summer. The number of baolerioplanklon was closely correlated with the concentration of chlorophyll a (r2= 0. 8301,n= 12,P <0.01) and waler temperature (r2=0.463,n= 12,P<0.01) respectively, but has no correlation with the nutriment. The results indicate that ihe nutrimental substance is very high in Lake Taihu, and is not be the limiting faclrs for bacterioplankton; the DOC is an important source for bacterioplanklon which comes from the ph^loplanklon.