海州湾星康吉鳗的摄食生态特征

根据2011年3—12月在海州湾及其邻近海域进行的5个航次的底拖网调查,通过分析516尾星康吉鳗(Conger myriaster)的胃含物样品,对其食物组成、食性类型、摄食强度、营养生态位以及营养级等摄食生态特征进行了初步研究。结果表明,星康吉鳗摄食的饵料种类有40余种,鱼类、虾类和头足类是其最主要的3种饵料类群,优势饵料生物有尖海龙(Syngnathus acus)、矛尾虾虎鱼(Chaeturichthys stigmatias)、鲜明鼓虾(Alpheus distinguendus)、枪乌贼(Loligo sp.)等。星康吉鳗的食性类型以底栖动物和游泳动物食性为主,其食物组成存在明显的季节变化和肛长变化,除在4个季节均摄食大量的鱼类和虾类外,秋季还摄食大量头足类。不同肛长组星康吉鳗摄食的主要饵料种类存在明显差异:肛长小于70 mm的星康吉鳗主要摄食枪乌贼,70~99 mm的星康吉鳗主要摄食绯(Callionymus beniteguri)和鲜明鼓虾,大于100 mm的星康吉鳗则主要以枪乌贼、尖海龙(Syngnathus acus)和鲜明鼓虾为食。星康吉鳗的空胃率和平均胃饱满指数存在明显的季节变化,空胃率夏季最低,春季最高;平均胃饱满指数春季最低,秋季最高。星康吉鳗的营养级为4.17,表明其在海州湾食物网中处于较高的营养位置。本研究发现,海州湾星康吉鳗的摄食随季节和肛长的变化,主要与其栖息海域中优势饵料生物的种类组成和丰度有关,因此,通过定期监测星康吉鳗的摄食可间接了解基础饵料生物种类和数量的变动情况,同时也为食物网的构建和生态系统营养动力学的研究提供基础资料。

Feeding ecology of Conger myriaster in Haizhou Bay

  Seasonal bottom-trawl surveys were conducted in Haizhou Bay, China from March to December 2011. A total of 516 Conger myriaster stomach samples were analyzed to study their feeding ecology, including diet composi- tion, feeding type, feeding intensity, trophic niche, and trophic level. The results show that the prey items of C. myri- aster included more than 40 species, and fish, decapods, and cephalopods were the dominant prey groups. Syngnathus acus, Chaeturichthys stigmatias, Alpheus distinguendus, and Loligo sp. were the major prey species of C. myriaster. Benthic animals were the dominant C. myriaster prey type, followed by swimming animals. The diet composition of C. myriaster had clear seasonal and length variations, and fish and shrimp were the major prey groups throughout all four seasons, whereas cephalopods were the most important prey during autumn. Loligo sp. were the dominant prey group of the C. myriaster with anal length < 70 mm, whereas Callionymus beniteguri and A. distinguendus were the dominant prey groups of the 70–99 mm C. myriaster. Loligo sp., Syngnathus acus, and A. distinguendus were the dominant prey groups of the C. myriaster > 99 mm. Percent of empty stomach and mean stomach fullness index of C. myriaster varied seasonally. The lowest and highest percent of empty stomach occurred in summer and spring, respectively. The mean stomach fullness index was lower in spring and higher in autumn. The C. myriaster trophic level was 4.17, indicating that it was in a high trophic position in the Haizhou Bay food web. The feeding ecology of C. myriaster varied season- ally and ontogenetically, which was mainly due to variations of dominant prey species. These results will help with as- sessments of prey abundance and species changes and provide basic information for building a food web and under- standing the trophic dynamics in the Haizhou Bay ecosystem.