椒江口春、秋季浮游动物分布特征及与主要环境因子的关系

Distribution of Zooplankton in the Jiaojiang Estuary and Its Response to Environment Factors in Spring and Autumn

2009年5月和10月对椒江口(121.35°E～121.85°E,28.50°N～28.80°N)浮游动物进行调查,分析其群落结构、生物量和丰度的时空分布特征及与主要环境因子的关系.结果表明,该海域浮游动物有明显的季节变化,春季鉴定到14大类50种,卡玛拉水母(Malagazzia carolinae)为绝对优势种,秋季鉴定到14大类73种,优势种分别为百陶箭虫(Sagitta bedoti)、双生水母(Diphyes chamissonis)、亚强真哲水蚤(Eucalanus subcrassus)、微刺哲水蚤(Canthocalanus pauper)、中华胸刺水蚤(Centropages sinensis)和肥胖箭虫(Sagitta enflata);多样性指数为秋季(2.59)高于春季(1.82),生物量和丰度为春季(972.66 mg/m3和1 743.54 ind/m3)远高于秋季(65.30 mg/m3和31.94 ind/m3).总生物量和丰度的空间分布由优势种决定,春季高值区出现在咸淡水交汇的出海口处;秋季有沿河口向外递增的趋势.典范对应分析(CCA)表明,营养盐、盐度和溶解氧为影响春秋季椒江口浮游动物分布的环境因子;浮游动物群落存在明显的季节和空间异质性;各物种适宜的生态环境不同.与类似河口的现状相比,椒江口的浮游动物种类丰富,可能与影响该河口的水团多样有关;与历史资料相比,椒江口4、10月份浮游动物的生物量、丰度及优势类群保持相对稳定.

To investigate the temporal and spatial distribution of community structure, biomass and abundance of zooplankton in the Jiaojiang Estuary and its response to environmental factors in different season, two cruises in the Jiaojiang Estuary were carried out in May and October 2009, respectively. Totally, 106 species were identified in all samples, belonging to 16 groups. Among them copepod was the dominant group, followed by pelagic larva and hydromedusae. Our results indicated that species composition presented significant seasonal variation. Totally, 50 species in 14 groups were identified in spring, and Malagazzia carolinae was the predominant species in all samples. However, 73 species in 14 groups were identified in autumn, in which there were 6 dominant species： Sagitta bedoti, Diphyes chamissonis, Eucalanus subcrassus, Canthocalanus pauper, Centropages sinensis, and Sagitta enflata. The diversity index of zooplankton was higher in autumn （2.59） than that in spring （1.82）, while the average biomass and abundance in spring （972.66 mg/m3 and 1 743.54 ind/m3） were significantly higher than those in autumn （65.30 mg/m3 and 31.94 ind/m3）, The distribution of biomass and abundance were determined by the dominant species, which was related to ocean currents. The areas with higher biomass and abundance in spring were both in the intersectional estuary of brackish water. The biomass and abundance in autumn increased gradually from estuary to opening ocean. The correlation between community structure of zooplankton and environmental parameters was calculated by method of canonical correspondence analysis （CCA）, and the result showed that the mainly environmental factors influencing zooplankton distribution in the Jiaojiang Estuary were nutrients, salinity and dissolved oxygen. Each species represented strongly ecological adaptability to environment, and samples of zooplankton displayed apparent seasonal and spatial variation. Because of variety of water masses in the Jiaojiang Estuary, the number of zooplankton species in the Jiaojiang estuary was richer than other similar estuaries. Compared with the historical data, the biomass, abundance and dominant groups of zooplankton in the Jiaojiang estuary in April and October were kept relatively stable. Fig 9, Tab 6, Ref44