南沙珊瑚礁区波纹钩鳞鲀(Balistapus undulatus)食性和营养级分析

波纹钩鳞鲀(Balistapus undulatus)是一种在热带珊瑚礁海域中广泛分布的杂食性鱼类, 研究其自然环境中的食物组成有助于了解其食物来源及其在生态系统中的功能地位。但目前的认识仅限于他们是珊瑚礁区的海胆捕食者, 对其准确的食物组成和生态功能定位尚不清晰。本研究于2017年夏季在南沙珊瑚礁区采集了波纹钩鳞鲀样品, 通过特异性引物扩增波纹钩鳞鲀消化道中的线粒体细胞色素C氧化酶亚基Ⅰ(COⅠ)基因, 以高通量测序技术分析了其现场食物组成, 并测定了碳、氮稳定同位素以分析其营养级。研究结果显示, 波纹钩鳞鲀摄食的食物种类有13种, 分属于节肢动物门(Arthropoda)、脊索动物门(Chordata)和环节动物门(Annelida)。其中最主要的食物来源是节肢动物门扇蟹科的蟹类, 如滑面蟹(Etisus sp.)、Luniella pubescens、皱纹花瓣蟹(Liomera rugata)等, 分别占61.8%、6.7%和1.8%。鱼类也有一定的贡献, 占总食物序列的23.5%。同位素结果显示其营养级为3.71±0.07, 与分子检测的结果相符。研究结果表明波纹钩鳞鲀的主要食物是小型甲壳类动物以及植食性鹦嘴鱼, 这拓展了以往对波纹钩鳞鲀所扮演生态角色的认识。

Diet and trophic level analysis of triggerfish (Balistapus undulatuse) in coral reefs of Nansha

As an omnivorous and widespread fish in tropical coral reefs, Balistapus Undulatus is an important sea urchins predator according to previous observations. However, the accurate food composition and ecological function of B. Undulatus remain unclear due to the lack of food composition information in natural environment. Here, we studied samples of triggerfish collected from the coral reef of Nansha in the summer of 2017. We used the high-throughput sequencing method targeted on the Cytochrome c. Oxidase subunit I (COI) gene and stable isotopes method to analyze the gut content composition of B. Undulatus, and conducted trophic levels analysis. Thirteen species were detected, including Arthropoda, Chordata and Annelida. Crabs of the Xanthidae family were the most important food item, such as Etisus sp., Luniella pubescens and Liomera rugata, accounting for 61.8%, 6.7% and 1.8%, respectively. Fish also made a contribution, accounting for 23.5% of the total food sequence. The isotopic results show that the trophic level was 3.71±0.07, which was consistent with the results of molecular detection. The results show that the main food of triggerfish (B. Undulatus) was small crustaceans and herbivore parrotfish. This study deepens our understanding of the ecological role of triggerfish.