上海淀山湖刀鲚食性研究

刀鲚为淀山湖鱼类群落优势种,对刀鲚食性进行研究有助于了解该湖泊种间关系和生态系统结构。2009年8月-2010年7月在淀山湖收集381个刀鲚有效胃样本,采用传统胃内含物法对该鱼食性进行研究。结果显示:(1)刀鲚全年均有摄食活动,夏季饱满指数强度最高、冬季最低,秋季空胃率最高、春季最低。(2)刀鲚食物由13大类、30小类饵料生物组成。聚类分析表明,数量百分比(N%)、出现率(F%)及相对重要性百分比指数(IRI%)在衡量刀鲚食物重要性方面表现一致,而重量百分比(W%)与前三者存在显著差异。N%、F%和IRI%显示,枝角类和桡足类是刀鲚的主要食物来源;W%显示虾类、桡足类和鱼类为刀鲚的主要食物来源。(3)刀鲚食物重量组成存在显著的季节差异,但其数量组成无明显的季节变化。(4)综合各指数结果显示,淀山湖刀鲚主要摄食浮游甲壳动物、鱼类和虾类。刀鲚食物组成显示该鱼可通过下行效应促进浮游植物的生长,推测降低该鱼生物量将有利于淀山湖的生态修复。

Diet of Coilia nasus in Dianshan Lake of Shanghai, China

Coilia nasus is a dominant species in the fish community of Dianshan Lake and investigation on its diet composition contributes to understanding interspecific relationship and ecosystem structure of this lake. A total of 387 stomach specimens of C. nasus were collected in Dianshan Lake from August 2009 to July 2010. Based on those specimens, the diet composition of this fish was conducted using the traditional method of stomach contents. C. nasus preyed all year round with the highest index of fullness in summer and the lowest in winter, and with the highest rate of empty stomach in antumn and the lowest in spring. The diet composition of C. nasus covered 13 large and 30 small categories. Cluster analysis showed that numerical percentage (N%), occurrance rate (F%), and percent index of relative importance (IRI%) are consistent in measuring importance of each food category to C. nasus, all indicating that Cladocera and Copepoda were the main food sources for C. nasus; However, there were significant differences in measuring the contribution between gravimetric percentage (W%) and each of the three above mentioned indices. The W% displayed that the shrimp, Cladocera, and fish were the main food sources for C. nasus. The N% of the food composition of C. nasus did not significantly differ among seasons, but the W% of food composition did. Combining the results of all the four indices, we concluded that C. nasus in Dianshan Lake mainly feeds on crustacean zooplankton, fish and shrimp. The information on diets of C. nasus suggests that this fish may promote the growth of phytoplankton by top-down effect, implying that reduction of C. nasus' biomass would contribute to the ecological restoration of Dianshan Lake.