作 者 ：栾青杉,孙军*
期 刊 ：生态学报 2010年 30卷 18期 页码：4967~4975
关键词：浮游植物；群集结构；多尼骨条藻；典范对应分析；长江口；
Keywords:phytoplankton, community structure, Skeletonema dohrnii, canonical correspondence analysis, Yangtze River estuary,
摘 要 ：根据2005年9月8—15日在长江口及其邻近水域（30.5°-32.5° N, 121.0°-123.5° E）进行的多学科外业航次调查所获资料，对调查区浮游植物的群集特征及其与环境因子之间的关系进行了研究。结果表明：鉴定浮游植物98种（含变种和变型），硅藻是浮游植物中的主要类群；浮游植物生态类型多为温带近岸种，少数为暖水种和大洋种；优势种主要为多尼骨条藻、尖刺伪菱形藻、柔弱几内亚藻、翼鼻状藻细长变型和柔弱伪菱形藻；细胞丰度平均为256.4 个?mL-1，高值出现在调查区的中部偏南及东北部海域；Margalef物种丰富度指数、Shannon-Wiener物种多样性指数、Pielou′均匀度指数的分布显示：调查区东南部海域浮游植物多样性程度较高，物种均一性较好。物种与环境的典范对应分析显示：甲藻与环境因子中溶解氧的关系较为密切；多尼骨条藻与海水中硅酸盐和硝酸盐的关系较为密切，与海水盐度有很大的负相关性；各物种在排序图中的位置反映了其对不同环境资源的生态需求。
Abstract:A multi-disciplinary investigation was carried out during 8th to 15th in September 2005 in Yangtze River estuary and its adjacent coastal waters (30.5°-32.5°N, 121.0°-123.5°E). Phytoplankton and water samples were collected using 5 L Niskin bottles at the depth of 0 m, 5 m, 10 m, 20 m, 30 m and sea floor. The samples were subsequently fixed with buffered formaldehyde-seawater solution at a final concentration of about 2% to 5% in 250 mL polyethylene bottles. Cell enumeration and species identification were performed by using an inverted microscope (American Optical Ltd. USA) at 100X or 400X magnification after sedimentation for at least 24 h in 25 mL Utermhl chambers. Phytoplankton were identified to the lowest taxon (genus or species level). Physico-chemical parameters were measured in situ and nutrient concentrations (nitrate, nitrite, ammonia, phosphate and silicate) were determined colorimetrically. Canonical correspondence analysis (CCA) was applied to clarify the inter-relationship between the different phytoplankton species distribution associated with their habitat environmental conditions. CCA biplots were then performed by using the software CANOCO (version 4.0) after the lg (x+1) normalization of the species and environment data matrixes. The minimum and maximum values of water temperature (℃), salinity, pH, and dissolved oxygen (mg L-1) were: 23.2-27.3; 0.1-341; 6.7-9.4 and 4.4-16.9 respectively. The ranges of nitrate, nitrite, phosphate, silicate and ammonia were: 0.04-94.4; 0.01-2.6; 0.03-1.7; 0.14-171.9 and 0.01-4.9 (μmol L-1) respectively. Chlorophyll-a varied from 02 to 99 (μg L-1). Based on the data that collected both in situ and in laboratory, the characteristics of phytoplankton assemblage and their relationships with the environmental factors were studied. Presently, a total of 98 species of phytoplankton were recorded and the diatoms (Bacillariophyceae) formed predominant group. Out of 65 species of diatoms (Bacillariophyceae), 25 species of dinoflagellates (Dinophyceae), 4 species of greens (Chlorophyceae), 2 species of silicoflagellates (Chrysophyceae) and 2 species of blue-greens (Cyanophyceae) were found. Most of the species ecotypes were temperate-coastal, warm water and oceanic species were rarely appeared. Among the various species, Skeletonema dohrnii, Pseudo-nitzschia pungens, Guinardia delicatula, Proboscia alata f. gracillima and Pseudo-nitzschia delicatissima were the most abundant forms. Phytoplankton cell abundance varied from 0.2 to 8657.7 cells?mL-1 (averaging 256.4 cells?mL-1), with the high abundance in the middle and northeast of survey area. Bacillariophyceae abundance varied from 01 to 8657.3 cells?mL-1 (averaging 254.7 cells?mL-1), with the similar distribution pattern and habitats as that of the total phytoplankton abundance. However, Dinophyceae abundance was relatively low when compared to that of the Bacillariophyceae, with the average abundance of 1.6 cells?mL-1 (ranging 0-20.1 cells?mL-1). Vertical distribution profiles of phytoplankton abundance revealed that the high density of total phytoplankton and the dominant species like Skeletonema dohrnii was appeared in maximum turbidity of the Yangtze River mouth and the diluted water areas. Margalef, Shannon-Wiener and Pielou′ index were unevenly distributed in the study areas with high species diversity and evenness in southeast area. After comparing the historical data in literatures of the similar survey area with our results, we found that, there was marked increase both in phytoplankton total species and abundance, although there were method discrepancies and slightly difference in study areas. Causes might be linked to the increase in sewage water discharge by anthropogenic activities and the influence of large projects like the Three Georges Dam constructions. CCA results of the relationship between phytoplankton species and environmental factors indicated that there was strong relationship between Skeletonema dohrnii and silicate and nitrate contents. However, this species was negatively correlated with the seawater salinity. Phytoplankton species positions in CCA biplots revealed that their ecological demands for different environmental sources.
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