基于氮稳定同位素的黄河口海域鱼类群落营养级结构研究

Food webs are the foundation of the marine ecosystems. Nitrogen stable isotope combined with model formula can be used to indicate the trophic structure, and to further reveal the process of material recycling and energy flowing in food webs effectively. This study aims to build the trophic structure of fish community in the Yellow River Estuary based on nitrogen stable isotope. However, there are still some issues to be solved for improving the classic trophic model. In light of previous studies, some uncertain parameters such as isotope fractionation factor and reference value might cause the uncertainty of trophic formula, and then lead to considerable deviation between estimated value and real value. To resolve this situation, this project designs the processes as follows: 1) find out the typical fish species and their primary food sources in the Yellow River estuary by on-the-spot investigation; 2) analyze the nitrogen stable isotope values in amino acid level after designed feeding experiments; 3) optimize the isotope fractionation factors and reference values based on the front results of analysis; 4) calculate the trophic level values of the common fishes around Yellow River Estuary using the optimized formula. This study will be the foundation for building the integrated marine food webs of Yellow River estuary ecosystems. Besides, this study will also provide an optimized process on how to obtain more accurate trophic level values for other marine species, and furthermore, it is of great significance in terms of both science and application such as ecological environment protection, sustainable utilization of marine biological resources and scientific management of marine protected areas.

食物网是海洋生态系统的基础。利用氮稳定同位素作为指示物，结合模型公式构建食物网的营养级结构，能够有效的指示海洋食物网能量流动和物质循环过程。本项目以黄河口海域鱼类群落为研究对象，构建基于氮稳定同位素的营养级结构。鉴于目前营养级模型存在的问题，即模型公式中分馏系数和基准值的不确定性会导致营养级结果出现偏差，本项目拟通过以下研究过程解决这个问题：通过实地考察锁定黄河口海域典型鱼类主要摄食对象，结合室内的摄食实验分析鱼类摄食同化后氮稳定同位素在氨基酸水平上的分馏，获得更加准确的分馏系数和基准值，通过优化后的公式进一步计算获得更为准确的黄河口海域鱼类营养级。本项目的实施，是构建完整的黄河口海洋生态系统食物网营养结构的基础，也为其它物种营养级计算提供更优的示例，而且对实现海洋保护区的生态环境保护、生物资源可持续利用，以及保护区科学管理等都具有重要的科学意义。

食物网作为物质循环、能量流动和信息传递的渠道，一直是海洋生态系统研究的重要内容，其中各物种的营养级又是海洋食物网研究的基础。稳定同位素分析近年来被越来越多的应用到海洋食物网研究。氮是生物有机体的重要组成元素，在有机体新陈代谢的转氨基过程中，其稳定同位素会在食物网营养级间产生明显的分馏，这一特征与模型公式相结合，能够有效的指示海洋生物物种在食物网中的营养级位置。不仅如此，氮稳定同位素特征还可以与碳稳定同位素相结合，进一步揭示种群间的摄食和竞争关系，以及明确海洋生态系统食物网的物质和能量来源。本研究利用稳定同位素指示了黄河口近海主要鱼类和无脊椎动物的主要食物来源及贡献度，基于模型优化，获得相应营养级数值，构建黄河口海域鱼类群落营养级结构。本项目的实施，是构建完整的黄河口海洋生态系统食物网营养结构的基础，也为其它物种营养级计算提供更优的示例，而且对实现海洋保护区的生态保护、生物资源可持续利用，以及保护区科学管理等都具有重要的科学意义。课题组后续将继续在庙岛群岛海域开展相关的食物网营养关系研究，应用于推动国家海洋公园建设。