Analysis of feeding ecology differences between natural and cultured populations of Oplegnathus fasciatus based on stable isotope technology(基于稳定同位素技术的条石鲷自然和养殖群体摄食生态差异分析)

Oplegnathus fasciatus is a typical reef-loving fish. In order to understand the feeding ecological characteristics of O. fasciatus, natural populations of O. fasciatus were collected in the waters of the Yangtze River Estuary and island and reef waters, and cultured populations of O. fasciatus were collected in the Xixuan Island Farm. The stable isotope technology was applied to study their feeding habits and trophic niche. The results showed that the ranges of muscle δ13C and δ15N of natural populations were －19.75‰ to －16.88‰ and 8.68‰ to 13.14‰ in island and reef waters, respectively; the muscle δ13C range of natural populations was －21.6‰ to －17.39‰, and the muscle δ15N range was 9.68‰ to 13.76‰ in the Yangtze River Estuary; and the muscle δ13C and δ15N of the cultured population ranged from －21.82‰ to －19.51‰ and 10.51‰ to 12.46‰, respectively. There was significantly lower muscle δ13C of the cultured population than that of natural population in the Yangtze River Estuary and island and reef waters (P＜0.05), and muscle δ15N was significantly higher than that of natural population in island and reef waters (P＜0.05), but there was no significant difference between muscle δ15N in natural population in the Yangtze River Estuary (P＞0.05). The muscle δ13C of natural population in island and reef waters was significantly higher than that in the Yangtze River Estuary (P＜0.05), and the muscle δ15N was significantly lower than that in the Yangtze River Estuary (P＜0.05). The results of correlation analysis showed that body length had no significant effect on muscle δ13C and δ15N (P＞0.05) in the Yangtze River Estuary and Xixuan Island Farm populations while body length had no significant effect on muscle δ13C in island and reef waters (P＞0.05), but had a significant effect on muscle δ15N (P＜0.05). There was no significant difference in the trophic niche width between the island and reef waters [corrected standard ellipse area (SEAc)=3.00‰2] and the Yangtze River Estuary (SEAc=2.91‰2), but the average trophic level was higher in the Yangtze River Estuary, which may depend on the trophic level of different ecosystems and the utilization capacity of habitat resources. This study provides basic information on the diet of O. fasciatus for better protection of its resources.(为掌握不同生境条石鲷（Oplegnathus fasciatus）的摄食生态特征，根据采自长江口海域、岛礁海域（自然群体）及西轩岛养殖场（养殖群体）3个不同水域的条石鲷样品，采用稳定同位素技术对其摄食习性及营养生态位进行研究。结果表明：岛礁海域条石鲷自然群体肌肉δ13C、δ15N值范围分别为－19.75‰～－16.88‰、8.68‰～13.14‰，长江口海域自然群体肌肉δ13C、δ15N值范围分别为－21.6‰～－17.39‰、9.68‰～13.76‰，养殖群体肌肉δ13C、δ15N值范围分别为－21.82‰～－19.51‰、10.51‰～12.46‰。养殖条石鲷肌肉δ13C值显著低于长江口海域和岛礁海域自然群体（P＜0.05），其肌肉δ15N值显著高于岛礁海域自然群体（P＜0.05），但与长江口海域自然群体肌肉δ15N值的差异不显著（P＞0.05）。岛礁海域自然群体肌肉δ13C值显著高于长江口海域（P＜0.05），肌肉δ15N值显著低于长江口海域（P＜0.05）。相关性分析结果显示，长江口海域自然群体与西轩岛养殖群体的体长对肌肉δ13C、δ15N值均无显著影响（P＞0.05），岛礁海域自然群体的体长对肌肉δ13C值无显著影响（P＞0.05），但其体长对肌肉δ15N值影响显著（P＜0.05）。此外，长江口海域条石鲷的营养生态位宽度与岛礁海域相差不大[岛礁海域校正标准椭圆面积（corrected standard ellipse area, SEAc）=3.00‰2，长江口海域SEAc=2.91‰2]，但其平均营养级更高，这可能取决于不同生态系统的营养层次和条石鲷对栖息地资源的利用能力。本研究为更好地保护条石鲷资源提供了饮食结构方面的基础信息。)