基于碳氮稳定同位素技术研究辽东湾海蜇的食性和营养级

应用稳定同位素技术分析了渤海辽东湾海蜇及其可能摄食饵料生物的碳、氮稳定同位素比值，对其食物组成和营养级进行了研究.结果表明： 辽东湾海蜇的δ¹³C值范围是-20.27‰～-23.06‰，跨度为2.79‰，平均值为-21.33‰；δ¹⁵N值范围是6.82‰～10.03‰，跨度为3.21‰，平均值为8.25‰.海蜇的饵料生物主要包括悬浮物、浮游植物、鱼卵、≤1000 μm 浮游动物、1000～1500 μm 浮游动物和＞1500 μm 浮游动物，其中以≤1000 μm 浮游动物为主，贡献率高达71%～88%；其他饵料生物的重要性由高到低依次为>1500 μm浮游动物、1000～1500 μm浮游动物、悬浮物、浮游植物和鱼卵，其平均贡献率分别为6%～19%、0%～22%、0%～10%、0%～8%、0%～2%.经检验发现，海蜇伞径长与δ¹⁵N的相关性不显著(P >0.05)，而与δ¹³C呈显著负相关(P<0.05).以悬浮物为基准的辽东湾不同伞径组海蜇的营养级范围为2.79～3.88，平均营养级为3.28.本研究结果说明，海蜇作为大型浮游动物在辽东湾生态系统中对小型浮游动物的能量传递起着关键的调控作用，研究结果将为深入研究辽东湾生物群落的营养结构及整个生态系统的物质循环与能量流动提供基础资料.

Feeding habitats and trophic levels of Rhopilema esculentum Kishinouye in Liaodong Bay based on analyzing carbon and nitrogen stable isotopes.

By using stable isotope techniques, we analyzed the carbon and nitrogen stable isotope ratios of Rhopilema esculentum Kishinouye and its potential feed materials in Liaodong Bay of Bohai Sea, aiming to identify potential food sources and trophic levels of R. esculentum . The results showed that the δ¹³C and δ¹⁵N values for R. esculentum ranged from -20.27‰ to -23.06‰ (ave raged at -21.33‰), and from 6.82‰ to 10.03‰ (averaged at 8.25‰), respectively. The main food sources for R. esculentum included suspended materials, phytoplankton, fish eggs, zooplankton (≤1000 μm), zooplankton (1000-1500 μm), zooplankton (>1500 μm), among which, zooplankton (≤1000 μm) was the most important food source and contributed 71%-88% of the total food sources, followed by zooplankton (>1500 μm) (6%-19%), zooplankton (1000-1500 μm) (0%-22%), suspended materials (0%-10%), phytoplankton(0%-8%) and fish eggs (0%-2%). A Pearson correlation test indicated that there was significant negative relationship between the diameter and δ¹³C value of R. esculentum (P<0.05), while no significant correlation was found between its diameter and δ¹⁵N value (P>0.05). The trophic level of R. esculentum ranged from 2.79 to 3.88 depending on diameter classes,with a mean valu of 3.28 These results indicated that R. esculentum plays a key role in controlling microzooplankton in the Liaodong Bay, which is significant for providing deeper understanding into the tropic structure of biological communities as well as into the material cycles and energy flow of entire ecosystem in the Liaodong Bay.