西南大西洋阿根廷滑柔鱼耳石元素组成

An analysis of element composition in the statoliths of Illex argentisnus squid in the Southwest Atlantic Ocean

耳石微量元素越来越广泛地被用于头足类群体划分、洄游史等领域的研究。根据我国鱿钓船2007、2008和2010年在西南大西洋生产期间采集的阿根廷滑柔鱼样本,利用激光剥蚀电感等离子质谱法(Laser ablation inductively coupled plasma mass spectrometry,LA-ICP-MS)按不同群体、不同性别和不同生长阶段,分析了33枚阿根廷滑柔鱼耳石的元素组成及分布特性。结果表明,阿根廷滑柔鱼耳石主要由56种元素组成,含量最多的前10种元素分别为钙Ca、锶Sr、钠Na、磷P、钾K、铁Fe、镁Mg、钡Ba、硼B、镓Ga。方差分析表明(ANOVA),不同性别间Ca、Sr、Na、P、K、Fe、Mg、Ba、B、Ga都不存在显著性差异(P>0.05)。冬季孵化群和秋季孵化群间耳石的Sr、Na、Mg、Ba和B存在显著性差异(P<0.05),Ca、P、K、Fe和Ga则不存在显著性差异(P>0.05)。耳石的核心区、后核心区、暗区和外围区等不同部位间的Na、Ba和Ga不存在显著性差异(P>0.05),Ca、Sr、P、K、Fe、Mg和B则存在显著性差异(P<0.05)。研究表明,Sr和Mg含量及其分布特性最适合用于研究阿根廷滑柔鱼的群体划分、洄游史等渔业生态学特性。

The shortfin squid, Illex argentinus, is a neritic-oceanic species distributed along the continental shelf and slope waters of Uruguay, Argentina and the Falkland Islands in the Southwestern Atlantic Ocean between latitudes 20° S and 55° S. They occur more abundantly in the area of 35°--52°S ,which supports an important jigging fishery on the Patagonian shelf and plays a significant role in the regional ecosystem. I. argentinus is an opportunistic species having rapid growth, a short life cycle, opportunistic feeding, and a high degree of intrapopulation differentiation. Statoliths of cephalopods are small calcareous structures with high resistance to erosion and recording important information all through its life. It is usually used for estimating ages and growth, identifying population structures by analyzing their microstrueture, deducing possible migratory routes and reconstructing habitat environment of cephalopods by the analysis of trace elements and isotopes in statolith, lllex argentinus supports an important commercial fishery in the southwest Atlantic. Understanding of population structure, migration and early life history are essential in sustainable exploitation and management of this squid. Elements of 33 statoliths of I. argentines collected in the Southwest Atlantic Ocean during 2007, 2008 and 2010 by Chinese squid jig fishing fleets were analyzed with Laser ablation inductively coupled plasma mass spectrometry （LA-ICP-MS） for different hatching groups, sexes and life history stages. The results indicated that the statolith of I. argentinus contained 56 elements, and calcium （Ca）, strontium （Sr）, sodium （Na）, phosphorus （ P）, potassium （K）, iron （Fe）, magnesium （ Mg）, barium （Ba）, boron （B）, gallium （Ga） were the ten most abundant elements. The analysis of variance （ANOVA） showed that there was no significant difference in all element distributions between sexes （P〉0.05） ; however, significant difference existed in the St, Na, Mg, Ba, B （P〈0.05） and no significant difference was found in the Ca, P, K, Fe and Ga between different hatching groups （P〉0.05）. Significant difference existed in all of the ten most abundant elements except for Na, Ba and Ga among different growth zones including nuclear part, postnuclear part, dark zone and peripheral zone in statolith （P〈0.05）. This study suggested that Sr and Mg were the best two trace elements to be used in the study of the population structure and life history of I. argentines.