运用稳定同位素技术研究千岛湖秋季刺网渔获物的食性和营养级

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。

Study on the feeding habits and trophic levels of the gillnet catches of Qiandao Lake in autumn by stable isotope technology

By using stable isotope techniques, the food sources and trophic levels of catches from gillnets were analyzed from September to November, 2011 in Qiandao Lake. Results showed that δ13C values of each food sources varied between -29.7 ——23.9 , among which, the highest δ13C values was seen in phytoplankton, with the lowest in particulate organic matter （POM）. The food sources of δ15N value range is small, with the highest phytoplankton （8.5 ）, the lowest particulate organic matter the lowest （5.1 ）. In contrast to isotope value distribution trend of food sources,consumers of δ13C values range was relatively small （-29.7——21.6）, and then δ15N range was relatively large （5.1 -14.8 ）. Consumers of trophic level from 1.9 to 3.6, belong to the three nutrition levels, the trophic level of fishes all distributed between the third to the fourth trophic level having good consistency with the feeding characteristics. But as an invasive species, herbivores fish Megalobrama amblycephala and omnivorous fish Ietalurus punetaus trophic level as high as 3.4 and 3.0, which inicated that feeding habits changed greatly in Qiandao Lake. Isotope tracer method research results also showed that the carbon source primarily is phytoplankton in Qiandao Lake water ecosystem.