吕泗渔场两种石首鱼科鱼类营养生态学特征:来自稳定同位素的证据

Trophic ecology based on stable isotope for two species of fish Larimichthys polyactis and Collichthys lucidus(Perciformes,Sciaenidae)from Lüsi fishing ground

本研究使用稳定同位素方法,分析及比较了吕泗渔场两种重要石首鱼科鱼类(小黄鱼Larimichthys polyactis、棘头梅童鱼Collichthys lucidus)的营养生态学特征。结果表明,不同体长组间小黄鱼和棘头梅童鱼的稳定碳同位素差异不显著(p>0.05),而稳定氮同位素差异显著(p<0.05)。小黄鱼的营养级要显著高于棘头梅童鱼(p<0.05)。聚类分析的结果可将小黄鱼的体长组分成两大组,包括>140~190、>130~140、>120~130、>80~90 mm一组和剩余的体长组;棘头梅童鱼的体长组可分为>140~190、>130~140 mm一组和剩余体长组。IsoSource模型的结果显示,浮游植物对小黄鱼、棘头梅童鱼的碳源贡献比例为43.38%和36.38%;底质有机物(Sedimental Organic Matter,SOM)对小黄鱼、棘头梅童鱼的碳源贡献比例为40.66%和43.70%。因此判定小黄鱼和棘头梅童鱼的潜在碳源主要是浮游植物和SOM。本研究还发现小黄鱼食性转变的体长临界点为80 mm,而棘头梅童鱼为110 mm,反映了棘头梅童鱼在生活史中转变食性行为的发生时间可能比小黄鱼晚。

In this study,we use stable isotope method to analyze and compare the trophic ecology of two species of important commercial Sciaenidae fish,small yellow croacker(Larimichthys polyactis)and big-head croacker(Collichthys lucidus)in Lüsi fishing ground.The result showed that it is no significant difference in stable carbon isotope(p>0.05)but significant in stable nitrogen isotope(p<0.05)between the different lengths of L.polyactis and C.lucidus.The tro-phic level of L.polyactis was significantly higher than that of C.lucidus(p<0.05).The clustering analysis demonstrated that the body lengths of two fishes could each be separated into two groups.It could be the group of>140-190,>130-140,>120-130,>80-90 mm and the rest body length for L.polyactis.And the group of>140-190,>130-140 mm and the rest body length for C.lucidus.IsoSource model showed that the contributions of phytoplankton to L.polyactis and C.lucidus were 43.38%and 36.38%,respectively,and the contributions of sedimental organic matter(SOM)were 40.66%and 43.70%,respectively,which determined that phytoplankton and SOM were main potential carbon sources for two species of fish.We also found that the critical point of body length of diet shift of L.polyactis is 80 mm,smaller than that of C.lucidus(110 mm),reflecting that C.lucidus changed its dietary behavior later than the growth and development stage of L.polyactis.