基于稳定同位素方法的闽江口常见鱼类群落营养结构的季节性变化

为了解闽江口常见鱼类群落的营养结构特征,于2015年冬季(1月)、春季(5月)、夏季(8月)、秋季(11月)采集闽江口底拖网渔业资源样品,利用稳定同位素分析闽江口常见鱼类群落营养结构特征及其季节性变化,并计算了基于δ¹³C-δ¹⁵N量化的7个营养结构的群落范围指标.结果表明: 闽江口常见鱼类群落除夏季和秋季的δ¹³C值之间不存在显著性差异,其余各季节之间δ¹³C值均差异显著;δ¹⁵N值春季与其余3个季节都表现出显著性差异,而其余3个季节δ¹⁵N值互相之间均无显著性差异.稳定同位素的量化指标表明: 闽江口常见鱼类群落的营养结构存在季节差异,春季的生态位总空间(TA)、核心生态位空间(SEAc)、鱼类基础食物来源(CR)、营养长度(NR)、鱼类营养多样性(CD)均为四季的最大值;从夏季至秋季再到冬季,生态位总空间(TA)、核心生态位空间(SEAc)、鱼类基础食物来源(CR)、营养长度(NR)、鱼类营养多样性(CD)和营养位置差异(MNND)均逐步上升.闽江口常见鱼类群落营养结构的季节差异可能与鱼类生殖洄游和群落内食源多样性的变化密切相关.

Seasonal variation in trophic structure of fish community in Minjiang Estuary based on stable isotope technique

To study the trophic structure of fish community in Minjiang Estuary, we measured the carbon and nitrogen stable isotope ratios (δ¹³C and δ¹⁵N) of common fish species sampled in winter (January), spring (May), summer (August) and autumn (November) of 2015 by trawling, as well as seven quantitative metrics (ratios range of δ¹⁵N, NR; ratios range of δ¹³C, CR; total area, TA; standard ellipse area, SEAc; average distance of centroid, CD; mean nearest neighbor distance, MNND; standard deviation of nearest neighbor distance, SDNND). The results showed significant differences of δ¹³C values among all the seasons except between summer and autumn. There were significant differences of δ¹⁵N values between spring and other three seasons but no significant difference among summer, autumn, and winter. According to the results of the seven quantitative metrics, trophic structure of common fish community remarkably varied among the four seasons, as TA, SEAc, CR, NR, CD and MNND increased in succession from summer, autumn, winter to spring. Our results indicated that seasonal differences in trophic structure of common fish community were related to the fish spawning migration and the diversity of food source.