运用碳氮稳定同位素技术探究中华绒螯蟹与无齿螳臂相手蟹的营养生态位特征

为进一步保护中华绒螯蟹栖息地和种质资源，科学评估长江蟹类的营养关系及资源的可持续开发利用，运用稳定同位素技术分析了在长江靖江、新开沙及狼山沙3个采集区域的中华绒螯蟹和无齿螳臂相手蟹的稳定同位素特征，并根据δ13C、δ15N值分析二者的生态宽幅及营养生态位面积。结果表明：中华绒螯蟹与无齿螳臂相手蟹的δ13C、δ15N值差异均具有统计学意义（P＜0.05）。中华绒螯蟹的δ13C值频率分布相对集中在-25.00‰~-23.00‰；无齿螳臂相手蟹的δ13C值频率分布相对集中在-26.00‰~-24.00‰，表明两种蟹均对某种饵料生物有所偏好，且中华绒螯蟹的δ13C值频率分布范围大于无齿螳臂相手蟹，表明其食物来源更广。中华绒螯蟹与无齿螳臂相手蟹的营养生态位存在重叠，表明二者存在饵料竞争关系。其中靖江江段两种蟹的营养生态位重叠程度最大，表明二者在靖江江段食物竞争最激烈。中华绒螯蟹的δ13C值变幅(CR)、δ15N值变幅(NR)及营养生态位总面积(Ta)均大于无齿螳臂相手蟹，说明中华绒螯蟹对于饵料资源的竞争能力更强。

Trophic Niche on Eriocheir Sinensis and Chiromantes Dehaani Through Stable isotope Analysis

To protect the habitat and germplasm resources of Eriocheir sinensis furtherlly and assess the nutritional relationship of the Yangtze River crabs scientifically. Besides, providing reference for exploitation and utilization. Stable isotope technology was employed to in the analysis of the stable isotopes of Eriocheir sinensis and Chiromantes dehaani in Jingjiang section, Xinkai sand and Langshan sand of Yangtze River. In addition, the research detected the δ13C and δ15N values of Eriocheir sinensis and Chiromantes dehaani. The results are used to figure out the area of trophic niches and the niche widths of two species. As the results revealed, there were significant differences in δ13C between Eriocheir sinensis and Chiromantes dehaani（P<0.05). The range of δ13C signatures in Eriocheir sinensisis greater than those of Chiromantes dehaani, indicating that Eriocheir sinensis feeds on more food resources. The range of δ13C signatures in Eriocheir sinensis and Chiromantes dehaani are relatively concentrated at -25.00‰ to -23.00‰ and -26.00‰ to -24.00‰ respectively, which indicate that both species prefer certain food. There is an overlap of trophic niches between Eriocheir sinensis and Chiromantes dehaani indicating the inter composition for the two species. The overlap of trophic niches in Jingjiang section is larger, which shows that the inter composition between the two species in Jingjiang section is the most intense. The amplitude of δ13C signatures(CR), δ15N signatures (NR) and total trophic area(Ta) in Eriocheir sinensis are all greater than those of Chiromantes dehaani, which specifies that Eriocheir sinensis has more competitive power for food resources.