采用碳氮稳定同位素技术对黄海中南部鳀鱼食性的研究

Feeding habit study of Anchovy(Engraulis japonicus)in the central and southern part of the Huanghai Sea with stable isotope techniques

根据2005年4~5月在黄海和长江口海域进行的春季底拖网调查,应用稳定同位素方法研究了黄海中南部鳀鱼(Engraulis japonicus)及其可能摄食饵料的碳氮稳定同位素比值,结果表明:(1)黄海中南部鳀鱼的食物组成为不同粒径的浮游动物、太平洋磷虾(Euphausia pacifica)和仔稚鱼,其中以粒径为500~900μm的浮游动物为主,贡献比例占61%~84%;仔稚鱼贡献比例占16%~21%,较传统胃含物方法分析的结果小;(2)黄海中部海域鳀鱼的碳氮稳定同位素比值平均值较南部海域高,原因可能与各海域的能量来源不同或存在微食物环有关,也可能与不同海域鳀鱼的能量转换途径不一样,即与食物链长短不一有关.

Stable isotope techniques are commonly used to represent the trophic structure of aquatic systems. Based on the bottom trawl surveys in the central and southern part of the Huanghai Sea and adjacent sea area of Changjing River Estuary during the spawning season of Spring in 2005, we mainly focus on the stable carbon （13^C/12^C） and nitrogen isotope （15^N/14^ N） ratios of anchovy and its potential food, such as zooplankton, Euphausia pacifica, larvae and juvenile fish, Leptochela gracilis, Loligo beka in order to acknowledge the feeding habit of anchovy. Application of δ^13C and δ^15N in dietary study depends upon the differentiation in the isotopic composition of various food sources. The δ^13C and δ^15N values of anchovy and its potential food indicated that its food sources in these areas were composed of zooplankton, Euphausia pacifica, fish larvae and juvenile fish. Especially, 500-900μm zooplankton was the most important dietary component for anchovy, accounting for 61~84~ the fish larvae and juvenile fish was 16%~21%, which of the total food by weight, the food proportion of was less than the results with the method of stomach content analysis; the variations in δ^13C and δ^15N values of anchovy, in the central of the Huanghai Sea were higher than the area of southern part of the Huanghai Sea and adjacent sea of Changjing River Estuary, the reason were likely to difference between the sources of Anchovy energy or the length of the food chain in the different areas of the central and southern of Huanghai Sea and adjacent sea area of Changjiang River Estuary. Stable isotope analysis （d^3C and d^s N） can be a powerful tool in both identifying the source of organic matter that supports fish production and investigating food web remains untested using tradi tional dietary methods in the modern ecology.