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利用稳定性同位素技术,对2011年9月至11月期间利用浙江千岛湖主要渔具之一的刺网采集的渔获物开展了食物源和营养级的分析研究。结果表明,千岛湖鱼类主要食物源的δ13C值跨度范围较大(-29.7‰~-23.9‰),其中浮游植物的δ13C值最高,颗粒有机物(POM)的δ13C值最低。食物源的δ15N值变化范围较小,以浮游植物最高(8.5‰),颗粒有机物最低(5.1‰)。与食物源的同位素值分布趋势相反,消费者的δ13C值浮动范围相对较小(-29.7‰~-21.6‰),而δ15N值的浮动范围相对较大(5.1‰~14.8‰)。消费者的营养级从1.9到3.6,分属于3个营养等级,鱼类的营养级全部分布在第3到第4营养级之间,且与其食性特征有较好的一致性,但是两种外来种鱼类中的一种草食性鱼类团头鲂的营养级却高达3.4,而肉食性的斑点叉尾的营养级则仅为3.0,说明其在千岛湖的食性均已发生了很大变化。同位素示踪方法研究的结果还表明千岛湖水体中的碳源主要是浮游植物。
Using stable isotope techniques, food source and trophic levels were analyzed for catches collected from gill nets, one of the major fishing gear on Lake Qiandao, Zhejiang, from September to November 2011. The results showed that the δ13C values of the main food sources in the Qiandao Lake ranged from -29.7 ‰ to -23.9 ‰, with the highest δ13C value of phytoplankton and the lowest δ13C value of particulate organic matter (POM). The δ15N values of food sources varied a little, with the highest phytoplankton (8.5 ‰) and the lowest particulate organic matter (5.1 ‰). Contrary to the tendency of the distribution of isotope values of food sources, the δ13C values of consumers are relatively small (-29.7 ‰ ~ -21.6 ‰), while δ15N values are relatively large (5.1 ‰ ~ 14.8 ‰). Trophic levels of consumers ranged from 1.9 to 3.6, which belonged to 3 trophic levels. Trophic levels of fish were all distributed between trophic level 3 and trough 4, and were in good agreement with their feeding characteristics. However, The trophic level of a species of herbivorous fish in the species is as high as 3.4, while that of the carnivorous Picchu fossil is only 3.0, indicating that its feeding on the Thousand Island Lake has taken place very much Variety. The results of the isotope tracer method also show that the carbon source in Qiandao Lake is mainly phytoplankton.