九段沙湿地叶绿素a和初级生产力的季节变化

2010年12月至2011年10月按季节4次对长江口九段沙湿地水域8个采样点中叶绿素a浓度进行了调查分析,探讨了九段沙水域不同区域、不同季节初级生产力的特点。九段沙湿地叶绿素a在春季浓度最高,均值为5.90 mg/m3,且空间上在上沙和中沙之间的潮沟中达到最高值,秋季叶绿素a浓度(均值5.03mg/m3)较春季稍低,但空间差异性较春季小,其他季节的叶绿素a都较低。九段沙湿地的浮游植物初级生产力范围为87.75~744.79 mgC/(m2·d),其中下沙的初级生产力较强,而江亚南沙的初级生产力相对较弱。与其他邻近或功能相近海域相比,九段沙湿地中叶绿素a和初级生产力都不太高,与长江口高悬浮物的含量密切相关。另外叶绿素a和初级生产力与总磷的显著相关,说明九段沙湿地可能是营养元素磷限值的水域。

Seasonal changes of chlorophyll a and primary productivity in Jiuduansha Wetland

Chlorophyll a of eight sampling sites from Jiuduansha Wetland was investigated from 2010 to 2011, and spatial and temporal pattern of primary productivity calculated based on chlorophyll a was also analyzed in the present study. Highest concentration of chlorophyll a was detected in spring with the mean of 5.90 mg/m³, and appeared in tidal creek between Shangsha and Zhongsha. Chlorophyll a in autumn 5.03 mg/m³ was lower than that in spring, however, spatial difference was low. Chlorophyll a was very low in other seasons. Primary productivity in Jiuduansha Wetland was in the range of 87.75 -744.79 mgC/(m²·d), and the highest value appeared in the Xiasha and the lowest in Jiangyanansha. Chlorophyll a and primary productivity in Jiuduansha were not high compared with those values in other waters, which might be closely related to the high content of suspended solids in Yangtze River estuary. Moreover, significant correlation between chlorophyll a and primary productivity and TP indicated that Jiuduansha wetland might be phosphorus-limited waters.