基于稳定同位素的枸杞岛海藻场鱼类群落营养结构特征

NUTRIENT STRUCTURE CHARACTERISTICS OF FISH COMMUNITY IN SEAWEED BEDS OF GOUQI ISLAND,ZHOUSHAN BASED ON STABLE ISOTOPE ANALYSIS

为了阐明枸杞岛近岸海域食物网结构,为岛礁近岸海藻场鱼类群落结构变化提供研究依据,应用碳、氮稳定同位素技术方法,分析评估了舟山枸杞岛近岸海藻场主要鱼类群落的营养结构特征及其季节变化。结果表明,海藻场茂盛期(春、夏季)主要鱼类的δ^(13)C值范围为-20.4‰~-12.8‰,均值为-16.1‰,其δ^(15)N值范围为4.1‰~10.4‰,均值为8.4‰;海藻场衰退期(秋、冬季)主要鱼类的δ^(13)C值范围为-17.9‰~-14.4.‰,均值为-16.1‰,δ^(15)N值范围为7.6‰-12.9‰,均值为9.7‰。钩虾和麦秆虫对褐菖鲉(Sebastiscus marmoratus)、大泷六线鱼(Hexagrammos otakii)和斑头鱼(Agrammus agrammus)等海藻场定居种类的食源贡献率最大,浮游动物对黄姑鱼(Nibea albiflora)和皮氏叫姑鱼(Johnius belengerii)的等非藻场定居种类食源贡献最大;应用SIBER模型计算显示枸杞岛海藻场茂盛期的主要鱼类群落生态位空间、核心生态位空间、基础食物来源、营养多样性的值均大于衰退期。不同时期的鱼类营养结构存在差异,茂盛期位于多边形顶点的种类分别为赤鼻棱鳀、青鳞小沙丁、丝背细鳞鲀和黄姑鱼;而衰退期的种类为赤鼻棱鳀、棘头梅童鱼、黑鲷、斑鳍天竺鲷、红鳍天竺鲷、红鳍东方鲀和大泷六线鱼。研究表明海藻场对主要鱼类的碳源具有显著影响,海藻场茂盛期支撑了更高的生物多样性、食源多样性和群落营养结构。

In order to clarify the nutritional structure of fish communities in the coastal seaweed beds of Gouqi Island,Zhoushan,China,theδ^(13)C andδ^(15)N values of the fish community samples were measured using stable carbon and nitrogen isotope techniques.The contribution rate of potential food sources to various consumers in different seasons were calculated based on Isosource mixture model and seasonal variation of nutritional structure of fish communities were analyzed accordingly.Results illustrating that during flourishing period of the seaweed beds,δ^(13)C values of the fish in the coastal waters of Gouqi Island ranged from–20.4‰~–12.8‰,with an average of–16.1‰,and theδ^(15)N values ranged from 4.1‰to 10.4‰,with an average of 8.4‰.However,during the decline period,theδ^(13)C values ranged from–17.9‰to–14.4‰,with an average of–16.1‰,and theδ^(15)N values ranged from 7.6‰to 12.9‰,with an average of 9.7‰.The high trophic fish(such as juvenile black seabream)fed more on fish and shrimps.The most contribution rate of food sources for Scorpaenidae(such as juvenile Sebastiscus marmoratus and Agrammus agrammus)were from gammarid and Caprella acanthogaster;Zooplankton provided main food sources for Clupeidae fishes(such as Thrissa kammalensis and Collichthys lucidus and Pseudosciaena polyactis).Five quantitative indexes were calculated by Siber model,whose results indicates the values of niche space,core niche space,basic food source and nutrient diversity of common fish communities in flourishing period were higher than those in declining period.The algal field in flourishing period supported a higher biodiversity and food diversity of fish was greater.The nutrient length of the two seasons were equal and common fish had relatively stable food net structure and nutritional diversity level.