生态学报2017，Vol.37Issue(8)：2788-2795,8.DOI:10.5846/stxb201601280212
长江安庆江段刀鲚耳石微化学及洄游生态学意义
Otolith microchemistry of the estuarine tapertail anchovy Coilia nasus from the Anqing section of the Yangtze River and its significance for migration ecology
摘要
Abstract
Owing to its nutritional value and delicacy,the estuarine tapertail anchovy Coilia nasus (Actinopterygii,Clupeiformes,Engraulidae) is a highly valuable commercial fish from the Yangtze River of China.Unfortunately,wild resources of C.nasus have declined drastically because of anthropogenic activities,habitat degradation,and overfishing.Recently,C.nasus has been proposed to be listed as a Class Ⅱ protected species on China's List of Wildlife under Special State Protection.It is noteworthy that many mainstream sections in the lower reaches of the Yangtze River are the main distribution areas of C.nasus,including the Anqing section in Anhui Province.Because of empirical limitations with the current method of catch-survey analysis,it remains difficult to effectively understand the spatial and temporal dynamics of the diadromous migration and habitat utilization history of C.nasus in this river section.Alternatively,elemental microchemical patterns in otoliths have proven effective natural "fingerprints" that can provide a powerful approach to estimate precisely the diadromous migratory history of C.nasus.In the present study,a JXA-8100 electron probe X-ray microanalyzer (EPMA) was applied to investigate the otolith microchemistry characteristics of 10 C.nasus anchovies collected from the Anqing section of the Yangtze River in July 2008 for investigation of habitat "fingerprints" and migratory history.All the C.nasus individuals were traditional long jaw estuarine tapertail anchovies,with supramaxillae longer than the head.Microchemical results confirmed that all of the C.nasus fish were typical anadromous individuals,i.e.,the anchovies were born and hatched in freshwater habitats,but later migrated into estuarine brackish or high salinity seawaters as juveniles to grow,and then ascended to freshwater habitats again to reproduce.The results of EPMA line transect analysis generally showed that the otolith Sr/Ca ratio fluctuated significantly between low (＜ 3,reflecting the freshwater habitat) and high (＞ 3,reflecting the estuarine brackish water or seawater habitat) value phases.The evidence was supported by the 16 color Sr content profiles (red [highest] through yellow and green to blue [lowest]) obtained by EPMA mapping analysis.Furthermore,three types of migratory life histories could be separated among C.nasus individuals of this study based on differences in the otolith freshwater coefficient,Sr/Ca ratio,and Sr content map profile.Namely,these anchovies have the ability to adopt short-term,moderate-term,or long-term ontogenetic strategies in freshwater habitats,before they shift their habitats to estuarine brackish or high salinity sea habitats.These phenomena clearly reflect the flexible habitat use patterns,diversity of population composition,and fluctuation migration strategies of C.nasus anchovies in the Anqing section of the Yangtze River.In addition,although from previous studies it was believed that juvenile C.nasus spent the winter months in sea areas,the present study has provided new evidence to demonstrate that juvenile C.nasus may overwinter in freshwater habitats.All the aforementioned results provide an important theoretical basis for a more accurate understanding of the migration patterns,population compositions,and habitat backgrounds for the life history of C.nasus in the Anqing section of the Yangtze River.关键词
刀鲚/耳石/长江安庆江段/微化学/洄游Key words
Coilia nasus/otolith/Anqing section of the Yangtze River/microchemistry/migration引用本文复制引用
李孟孟,姜涛,陈婷婷,刘洪波,杨健..长江安庆江段刀鲚耳石微化学及洄游生态学意义[J].生态学报,2017,37(8):2788-2795,8.基金项目
国家自然科学基金项目(31372533) （31372533）
江苏省自然科学基金项目(BK20131089) （BK20131089）
