| 摘要: |
| 根据2006年6月2-11日在长江口低氧区及邻近水域(26°-34°N,121°-126°E)27个站位的调查,对长江口低氧区及邻近水域的浮游植物群落结构特征进行了相关研究。经Utermohl方法初步分析,共发现浮游植物130种,隶属4门57属。甲藻和硅藻是2006年6月长江口低氧区及邻近水域的主要浮游植物门类,其优势物种是:具齿原甲藻Prorocentrum dentatum (=Prorocentrum donghaiense)、米氏凯伦藻Karenia mikimotoi、尖刺伪菱形藻Pseudo-nitzschia pungens、柔弱伪菱形藻Pseudo-nitzschia delicatissima、锥状施克里普藻Scrippsiella trochoidea和具槽帕拉藻Paralia sulcata。调查区浮游植物物种以广温、广布型为主。本次调查海域浮游植物的细胞丰度介于0.0026×105-37.37×105个/dm3,平均值为1.47×105个/dm3;甲藻占浮游植物细胞丰度的比例最大,细胞丰度介于0.0002×105-32.01×105个/dm3,平均值为1.39×105个/dm3；其次为硅藻，细胞丰度介于0.0001×105-18.72×105个/dm3，平均值为0.52×105个/dm3。具齿原甲藻和米氏凯伦藻所占丰度比例分别达到45.81%和26.44%，优势度分别为0.30和0.18。具齿原甲藻细胞丰度最高值出现在调查海域北部3号站-20m水层，为3.19×106个/dm3；米氏凯伦藻细胞丰度最高值出现在调查海域西南部29号站表层，为1.71×106个/dm3。浮游植物细胞丰度在水体中的垂直分布为表层最大，随着水深增加而逐渐降低。根据浮游植物的表层分布和断面分布可以发现，细胞丰度高值主要集中在调查区的西南部和北部，东南部浮游植物细胞丰度较低。同时调查海域东南部浮游植物多样性指数和均匀度指数较高，近岸低氧区和总部区域则较低。调查区水体惩罚化现象明显，表层水和底层水之间氧的交换变弱，有机碎屑和浮游植物大量繁殖后沉降分解可能导致了底层低氧区的形成。 |
| 关键词: 浮游植物 物种组成 低氧区 断面分布 长江口 |
| DOI：10.11693/hyhz200806012 |
| 分类号: |
| 基金项目:国家重点基础研究发展规划(973)项目,2006CB400605号;中国科学院知识创新工程重点方向项目,KZCX2-YW-213号;国家自然科学基金项目,40676089号 |
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| PHYTOPLANKTON OF CHANGJIANG (YANGTZE RIVER) ESTUARY HYPOXIA AREA AND THE ADJACENT EAST CHINA SEA IN JUNE 2006 |
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WANG Dan1, SUN Jun1, ZHOU Feng2, WU Ying3
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1.Key Laboratory of Marine Ecology & Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071;2.State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, 310012;3.State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200062
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| Abstract: |
| Phytoplankton community and cell abundance were investigated during 2nd to 11th June 2006 at 27 stations of Changjiang (Yangtze River) hypoxia area and the adjacent East China Sea (26°-34°N,121-126°E). Water samples were analyzed by Utermohl method, recognizing 130 taxa phytoplankton that belong to 57 genera of 4 classes. Pyrrophyta and Bacillariophyta were the dominant functional phytoplankton in the study areas. The dominant species included, in descendent order, Prorocentrum dentatum (=Prorocentrum donghaiense), Karenia mikimotoi, Pseudonitzschia pungens, Pseudonitzschia delicatissima, Thalassiosira sp., Gymnodinium sp., Scrippsiella trochoidea, and Paralia sulcata, all being eurythermal species. Cell abundance of phytoplankton ranged from 0.0026 to 37.37 ×105 in average of 37.37×105 ind/dm3, of which Pyrrophyta ranked the first ranging 0.0002×105-32.01×105 averaged at 1.39×105 ind/dm3, followed by Bacillariophyta, 0.0001×105-18.72×105 in average of 0.52×105 ind/dm3 . Prorocentrum dentatum and Karenia mikimotoi took 45.81% and 26.44% respectively, in dominancy of 0.30 and 0.18. The largest cell abundance of 3.19×106 ind/dm3 for P. dentatum occurred at -20m layer at the 3rd station in the north of the survey areas, while that of K. mikimotoi was in hypoxia area at the 29th station in the southwest of survey areas, at 1.71×106 ind/dm3. Phytoplankton cell abundance were concentrated in surface water and reduced rapidly downwards. Results show that cell abundance was concentrated in the southwest and north of the survey areas, and low in the southeast. Meanwhile, the Shannon-Wiener diversity indices and Pielou’s evenness of phytoplankton community were high in the southeast and low in the center, and in low dissolved oxygen area nearshore. The water stratification was strong, causing weak oxygen change in vertical direction. Therefore, decomposition and sedimentation of organic particles and phytoplankton could result in the formation of low-oxygen zone in the bottom zone. |
| Key words: Phytoplankton, Species composition, Hypoxia area, Section distribution, Changjiang (Yangtze River) estuary |
