福建省九龙江江东库区沉积物微藻分布研究

Research on seasonal microalgae community structure in the sediments of Jiangdong Reservoir in Jiulong River

沉积物既是营养盐的储存库,也是藻类的休眠场所.本研究以九龙江北溪江东水库为研究对象,于2011年4月、6月、9月、12月采集表层沉积物,对其营养盐含量、表层沉积物微藻分布及丰度进行分析.结果表明,沉积物大部分为粉砂质粘壤土,该区域沉积物总碳含量为9140.2~17760.4 mg·kg^(-1),总氮含量为950.0~1600.4 mg·kg^(-1),总磷含量为483.7~856.2 mg·kg^(-1).库区表层沉积物微藻细胞丰度范围在7.41×105~2.17×106cells·g^(-1)底泥(以干重计),主要为硅藻门和绿藻门,分别占微藻比例的45.52%~86.42%和5.96%~35.55%.沉积物微藻总丰度与上覆水体浮游植物总丰度及隐藻、裸藻丰度呈显著负相关,反映了沉积物微藻对上覆水体浮游植物的影响.沉积物中蓝藻、隐藻、甲藻孢囊丰度分别与水温呈显著负相关,分别与溶解氧呈显著正相关,因而冬季沉积物中有相对高的微藻丰度.沉积物微藻丰度与含水率、粉粒分别呈显著性正相关,反映了沉积物微藻沿着水流方向的积累.

Sediment is the sink of both dormant phytoplankton and nutrients. This research investigated the seasonal nutrients contents and microalgae community structure in sediments from Jiangdong Reservoir of Jiulongjiang River,with samples collected in April,June,September and December 2011.The results show that the sediments are mainly silty clay loam,and the total carbon,total nitrogen and total phosphorus range from 9140. 2 to 17760. 4mg·kg-1,950.0 to 1600.4 mg·kg^（-1）,and 483.7 to 856.2 mg·kg^（-1）,respectively. The abundance of microalgae in the sediments falls in the range of 7.14×105~ 2.17×106cells·g^（-1）（ dry sediment）. The dominant microalgae species are diatoms and green algae,accounting for 45.52% ~ 86.42% and 5.96% ~35.55% of total microalgae abundance. Correlation analysis reveals the effects of some key environmental factors on the microalgae community structure in the sediments. Microalgae abundance is negatively correlated with that in the overlying water,representing the contribution of sediment dormant microalgae to aqueous algal blooming. As for the abundance of cyanobacteria,Cryptophyta and dinoflagellate cysts,they have a significant negative correlation with the overlying water temperature but positive correlation with dissolved oxygen. It explains their relatively higher abundance in sediments in winter season.The significant positive correlation of microalgae abundance with sediment moisture and silt content hints the accumulation of microalgae,particularly dinoflagellate cysts,along the water flow.