Stable isotope technique was applied to investigate the small and medium-size consumers including not only fish, shrimps, crabs, cephalopods, snails and bivalves, but also the specimens of their potential carbon sources, which were collected in the marine ranching area of Haizhou Bay during the spring of 2015. IsoSource model was adopted to calculate the contribution of potential carbon sources to the consumers. Biospeciemens collected in the summer of 2014 were compared with those in the spring of 2015, aiming to analyze the seasonal variation in the trophic structure of food web. Six quantitative community indices were calculated based on the isotope values of the organisms in Haizhou Bay. The results showed that the δ13C values of consumers ranged from -18.9‰ to -17.1‰, and the δ13C values of three potential food sources ranged from -18.1‰ to -23.4‰ in the spring of 2015. The calculation results of IsoSource model further demonstrated that the phytoplankton was the most important carbon source for consumers (80.8%), followed by sediment organic matter (10.8%) and particulate organic matter (8.4%). There was a significant difference in the δ13C values between the biospecimens in the summer of 2014 and those in the spring of 2015, while no significant difference was observed in δ15N values. Trophic structure of community-wide differed remarkably in different seasons indicated by the six quantitative community indices. The δ13C range, total area, mean nearest neighbor distance and standard deviation of nearest neighbor distance of the community were much higher in 2014 than those in 2015, but the δ15N range and mean distance to centroid showed no significant change. The trophic structure redundancy was lower in the summer of 2014 compared with that in the spring of 2015, however, the diversity of food resources was higher in the summer of 2014.
基于稳定同位素技术对2015年春季海州湾海洋牧场海域采集的中小型生物消费者,包括鱼类、虾类、蟹类、头足类、螺类和双壳类等与其潜在碳源样品进行分析,利用IsoSource模型计算该海域消费者碳源贡献率,并对2014年夏季生物学样品与2015年春季样品比较,分析食物网营养结构的季节性变化,根据稳定同位素测定结果绘制二维双标图,计算出6种营养结构的量化指标.结果表明: 2015年春季海州湾海洋牧场海域消费者的δ13C值范围为-18.9‰～-17.1‰,3种潜在碳源[浮游植物、悬浮颗粒有机物(POM)、沉积物(SOM)]的δ13C值范围为-18.1‰～-23.4‰,根据模型计算得出浮游植物对消费者的平均碳源贡献最大,为80.8%,其余依次为SOM和POM,分别为10.8%和8.4%.2014年夏季生物样品与2015年春季样品的δ13C值存在显著差异,而δ15N值无显著性差异;6种量化指标表明群落营养结构存在季节性差异, 2014年夏季的δ13C比值范围(CR)、总面积(TA)、平均最邻近距离(NND)和平均最邻近距离标准差(SDNND)均大于2015年春季,δ15N比值范围(NR)和平均离心距离(CD)无明显变化,夏季群落营养结构冗余度小于春季,且食源多样性水平高于春季,存在季节差异.
Keywords: Haizhou Bay; food web foundation; stable isotope; trophic structure.