基于内壳稳定同位素信息的东海太平洋褶柔鱼摄食与洄游

Feeding and migration of Todarodes pacificus in the East China Sea based on the stable isotopic information of gladius

通过对2018年、2019年东海太平洋褶柔鱼内壳进行连续切割,测定其碳、氮稳定同位素比值,利用营养生态位和稳定同位素序列分析了两年间太平洋褶柔鱼在其生长发育过程中的洄游和摄食情况,并初步分析了两年间洄游、摄食差异产生的原因。结果显示,两年间东海太平洋褶柔鱼群体均在内壳叶轴生长至距顶端120 mm处时开始向低纬度、近岸海域洄游,2019年洄游的范围更大,这可能是由厄尔尼诺事件发生所引起。随着个体的生长发育以及洄游过程,2018年太平洋褶柔鱼群体摄食的营养层次逐渐上升,2019年太平洋褶柔鱼群体总体摄食的营养层次变化不大。研究表明,内壳连续取样分析太平洋褶柔鱼摄食和洄游变化的可行性。

Todarodes pacificus,a significant warm oceanic cephalopod species,is relatively well understood in terms of population structure,age,growth and reproduction.However,the species'migration patterns and feeding habits remain elusive due to limitations in artificial breeding techniques and the shortcomings of stomach contents analysis.Further research is essential to elucidate the migration path and feeding habits of T.pacificus for effect-ive resource management.This study focused on the the proostracum of gladius of T.pacificus caught collected from the East China Sea in 2018 and 2019.The proostracum was sequentially sectioned,and the carbon and nitro-gen stable isotope ratios of fragments were measured.Using trophic niche and stable isotope sequence,we examined the migration and feeding behaviors of T.pacificus across its life history over two years and preliminar-ily explored the reasons for interannual variations in these behaviors.The trophic niche analysis revealed distinct and non-overlapping ranges for T.pacificus in 2018,while in 2019,the ranges were similar and overlapping[2018:total area(TA)3.11‰2,standard ellipse area(SEAc)0.81‰2;2019:TA 3.51‰2,SEAc 0.77‰2].The stable isotope sequence indicated significant changes in the values for T.pacificus when the gladius proostracum reached 120 mm from the distal end in both years.On the population level,the averageδ13C andδ15N values of T.pacificus from each spawning ground population in 2018 were positively correlated with gladius growth,while in 2019,only the averageδ13C values showed such a correlation.Statistical tests revealed significant differences in the averageδ13C values between 2018 and 2019(t-test,F=1.104,P<0.01),but no significant differences in averageδ15N values(t-test,F=3.903,P>0.05).The analysis indicated that T.pacificus individuals in 2018 originated from various spawning grounds,and all the individuals of T.pacificus in 2019 came from the same spawning grounds,whereas in 2019,they all came from the same grounds.In both years,the T.pacificus began migrating to low latit-udes and coastal waters once the gladius proostracum reached 120 mm,with prior movements confined to the vicinity of spawning ground.The broader migration range in 2019 may be attributed to the El Niño event.As T.pacificus individuals grew and migrated,their trophic level increased in 2018,whereas in 2019,it remained relat-ively stable.This study demonstrated the utility of continuous gladius sampling for analyzing the feeding and migration of T.pacificus,providing a scientific foundation for future research on T.pacificus.