三峡库区蓄水175m对汉丰湖不同生物类群δ13C、δ15N值的影响

于2010年蓄水前(7月)和蓄水后(12月)应用稳定碳、氮同位素方法对汉丰湖食物网中初级生产者和消费者δ13C、δ15N值变化规律进行了调查分析.结果显示:汉丰湖初级生产者颗粒有机物(POM)、固着藻类和水生植物δ13C、δ15N值分别为-28.45‰~-24.78‰、3.72‰~5.76‰,-25.81‰~-21.22‰、3.23‰~4.81‰,-27.99‰~-23.74‰、8.06‰~12.48‰.从蓄水前到蓄水后初级生产者(POM、固着藻类、水生植物)δ13C、δ15N(除水生植物)值均呈现贫乏趋势;消费者δ15N值变化规律与初级生产者一致,但其δ13C值无明显变化;汉丰湖鱼类食物网营养级长度均为3级,消费者中杂食性鱼类居多其碳源主要来源于固着藻类.新形成的汉丰湖水生生态系统已经形成了相对稳定的食物网结构.

Effects of the 175m impoundment (the first time) in the stable carbon and nitrogen isotope ratios (13C/12C and 15N/14N) of different organisms in Hanfeng Lake from the Three Gorges Reservoir

Stable carbon and nitrogen isotope ratios (13C/12C and 15N/14N) of primary producers and consumers were investigated between pre-impoundment and post-impoundment conditions in 2010, in order to describe the food web in the Hanfeng Lake. Overall the values of the primary producers, including particulate organic matter (POM), periphytic algae and aquatic plants samples, were -28.45‰~-24.78‰, -25.81‰~-21.22‰, -27.99‰~-23.74‰ for δ13C and 3.72‰~5.76‰, 3.23‰~4.81‰, 8.06‰~12.48‰ for δ15N, respectively. δ13C and δ15N in primary producers (except for aquatic plants) assumed an overall reduced tendency from pre-impoundment period to post-impoundment period. In addition, δ15N values in consumers presented an consistent variation trend to that in primary producers, while the δ13C values didn’t change significantly. Trophic level length of fish food web in Hanfeng Lake was three trophic levels (from pre-impoundment period to post-impoundment period) and the omnivorous fish whose carbon sources come from periphytic algae were the dominant group. These results showed that the aquatic ecosystem of Hanfeng Lake, which was a new artificial lake, had formed a relatively stable structure of fishes’ food web.