基于耳石微化学的大洋河刀鲚生境履历研究

THE HABITAT HISTORY OF COILIA NASUS IN DAYANG RIVERBASED ON OTOLITH MICROCHEMISTRY

为探明大洋河刀鲚(Coilia nasus)的“生境履历”,利用电子探针微区分析技术(EPMA)对2020年7月和9月采自大洋河下游水域20尾刀鲚的矢耳石进行了锶(Sr)和钙(Ca)的微化学分析研究。定量线分析结果显示,刀鲚样本均为淡水起源,淡水生境Sr/Ca比值在(1.49±0.61—2.75±0.53),淡水系数(Fc)在(0.08—0.52),淡水区域径长在(150—900μm)。进入第二变化阶段后“生境履历”波动显著,Sr/Ca比值变化可将大洋河刀鲚分为3种模式,第一种是中高值区(半咸水或海水)越冬,繁殖季溯河洄游至低值区(淡水);第二种是长期栖息于中高值区,无溯河洄游现象;第三种是在中高值区和低值区多次转换,DYH 05、19个体最高完成9次转换。Sr面分析结果也与上述Sr/Ca比值结果相同。这三种模式直观地反映出大洋河刀鲚群体“生境履历”的多样性特点。

The main economic fish species in Liaoning Province of China,the resource of Coilia nasus has sharply declined in recent years,and currently only small-scale fishing flooding can be seen in the Dayang River.In order to reconstruct C.nasus habitat history,an electron probe microanalyzer(EPMA)was used to analyze the Sr and Ca microchemistry patterns in otoliths of 20 C.nasus collected from the lower reaches of Dayang River in July and September 2020.Results of line transect analysis showed that the samples of C.nasus were of freshwater origin,and the Sr/Ca ratio of freshwater habitats were(1.49±0.61—2.75±0.53).The value of freshwater coefficient(Fc)in the C.nasus is between 0.08 and 0.52,and the diameter of the freshwater area is between 150 and 900μm.After entering the second change stage,the habitat history fluctuates significantly.The change of Sr/Ca ratio divided C.nasus into three types:(1)C.nasus overwintering in medium and high Sr/Ca ratio areas(brackish water or seawater),and migrates upstream to low Sr/Ca ratio areas(freshwater)during breeding season;(2)C.nasus live in medium and high Sr/Ca ratio areas for a long time without anadromous migration;(3)C.nasus were transformed for many times in the middle high Sr/Ca ratio areas and low Sr/Ca ratio areas,and DYH05 and 19 individuals completed the transformation for up to 9 times.The Sr content analysis result is also the same as the Sr/Ca ratio above.These three types intuitively reflect the upstream migration habits and habitat history characteristics of the C.nasus population in natural water bodies with different salinity levels,in order to provide a theoretical basis for scientifically and accurately grasping the living habits of C.nasus from the Dayang River,formulating strategies for protecting resources and habitats restoration of C.nasus from the Dayang River.