三亚湾肥胖软箭虫成体与幼体现场摄食差异研究

In situ feeding differences between adults and juveniles of chaetognath(Flaccisagitta enflata)in Sanya Bay

毛颚类是热带近岸海域中上层鱼类的食物来源,同时又是重要的肉食性浮游动物,数量丰富,然而其维持种群结构的生存策略尚不清晰。本文运用分子生物学技术,分析了三亚湾海域毛颚类优势种肥胖软箭虫(Flaccisagittaenflata)成体与幼体的肠道食物组成,以期从食物资源利用的角度揭示其维持种群结构的营养策略。研究结果显示,幼体和成体摄食的浮游生物种类分别为21种和19种,共同的食物类群有桡足类、小型水母类、硅藻和多毛类。成体与幼体食物偏好差异显著,成体主要的食物来源是小型水母类(59%),而幼体主要的食物来源是桡足类(60%);幼体营养生态位(5.16)高于成体(2.89),且二者食物重叠度低(0.21),表明成体与幼体食物分化明显。研究结果揭示,即使成体与幼体大量共存,它们也可以通过摄食分化避免食物资源竞争,这种分配策略对毛颚类保证足够幼体存活率和维持种群数量具有重要意义。

Chaetognatha is often the most abundant carnivorous zooplankton,and a vital food source for pelagic fish in marine ecosystem.However,their survival strategy of maintaining population structure in tropical coastal waters remains unclear.In this study,molecular method was applied to compare the field diet of juveniles and adults of dominant chaetognath species Flaccisagitta enflata in Sanya Bay.We discuss the nutritional strategies of chaetognaths maintaining substantial population structure from the perspective of resource utilization.The results show that there were 21 and 19 species fed by juveniles and adults,respectively.Copepods,small jellyfish,diatoms,and polychaets were common food groups of both juveniles and adults.Food preferences differed significantly between the juveniles and adults.Small jellyfish made up 59%of the whole diet composition in adults,while copepods became the most abundant food items(60%)in juveniles.The trophic niche of juveniles(5.16)was higher than that of adults(2.89),and trophic overlap between them was low(0.21),suggesting that chaetognaths have obvious dietary shifts during different growth stages.These results reveal that even though adults and juveniles coexist in the same region with large numbers,they can reduce food competition by feeding differentiation.This feeding strategy is of great signiHcance for maxillary species to ensure juvenile survival and maintain substantial population structure.