广西防城港湾周年浮游植物生态特征

Annual change of phytoplankton ecological features in Fangchenggang Bay of Guangxi,South China

2007年3、6、9和12月,对防城港湾海域浮游植物的种类组成、优势种类、群落结构、丰度分布进行了调查,分析了浮游植物丰度、生物指数及其与环境因子的相关性.共鉴定出浮游植物54属138种.其中硅藻门37属112种;甲藻门12属21种;绿藻门和金藻门各2种,蓝藻门1种.全年浮游植物优势种主要为硅藻门的中肋骨条藻.浮游植物种数呈现湾内低于湾外、由春至冬减少的趋势,浮游植物细胞丰度则呈由湾内向湾外递减的趋势.不同季节调查海区浮游植物细胞丰度平面分布格局具有显著差异,夏季(6月)浮游植物丰度最高,达151.39×104cells·dm-3,冬季(12月)丰度最低,为0.35×104cells·dm-3.春季防城港湾海域的浮游植物多样性较高,物种较丰富.相关性分析表明,浮游植物群落分布与营养盐、水温、盐度等环境因子存在一定的相关性.西湾内的S1和S2测站,受防城江径流及潮汐等水动力条件的作用,盐度较低,富营养化程度较高,夏季时中肋骨条藻会大量增殖,甚至具有发生赤潮的隐患.

In March,June,September,and December 2007,investigations were conducted on the species composition,dominant species,community structure,and abundance distribution of phytoplankton in the Fangchenggang Bay of Guangxi.Based on the investigation data,the phytoplankton abundance,biotic index,and their correlations with environmental factors were analyzed.A total of 138 species of 54 genera were identified,among which,112 species belonged to 37 genera of diatoms,21 species belonged to 12 genera of dinoflagellates,2 species belonged to chrysophyta,2 species belonged to chlorophyta,and 1 species belonged to cyanophyta.In whole year,the dominant species was Skeletonema costatum.The species number had a trend decreasing from the outer to the inner of the Bay and from spring to winter,while the cell abundance was decreased from the inner to the outer of the Bay.There was an obvious annual change in the cell abundance,being the highest（151.39 × 104cells·dm-3） in summer（June） and the lowest（0.35 × 104 cells·dm-3） in winter（December）.In spring,both the diversity and the species number were higher.Correlation analysis demonstrated that the distribution of phytoplankton community had definite correlations with water nutrient content,temperature and salinity.At the observation stations 1 and 2 in west Bay,due to the effects of Fangcheng River runoff and hydrodynamic forces such as tide,water salinity was lower and nutrient content was higher,and accordingly,S.costatum cells in summer could greatly reproduce,even result in high probability of red tide.