东太平洋茎柔鱼的耳石微结构

根据采集于东太平洋哥斯达黎加、秘鲁和智利外海的茎柔鱼耳石样本,分析了其生长纹、标记轮和其他异常结构。结果显示,耳石生长纹由明暗相间的环纹组成,按照生长纹宽度的不同可分为后核心区、暗区和外围区3个明显的生长区。通过对后核心区和暗区生长纹的计数显示,哥斯达黎加、秘鲁和智利外海3个海区的茎柔鱼仔鱼的年龄分别约为26、32和33日龄,稚鱼的年龄分别约为86、84和88日龄。茎柔鱼的耳石微结构中存在7类标记轮,它们的形成与茎柔鱼自身的内源节律(孵化、交配、产卵等)和外部环境压力(温度骤变、捕食者攻击等)等因素有关。研究还在个别茎柔鱼的耳石中发现一些不规则的异常结构(副核心、附生长纹、附中心)和生长纹方向颠倒的现象,推断它们的形成可能是由于外力作用使得耳石被破坏或耳石脱离原先的位置所造成的。

Statolith microstructure analysis of the Humboldt squid (Dosidicus gigas) in the eastern Pacific Ocean

This study analyzed the growth increments, checks and aberrant structures of statolith microstructure for Dosidicus gigas in Costa Rican, Peruvian and Chilean waters in the eastern Pacific Ocean. The growth increments of the statolith are composed of one light and one dark circle line. Three different growth zones were defined bases on the width of growth increment that is postnucelar, dark and peripheral zone. The average age of paralarvae is about one month with 26 days in Costa Rica, 32 days in Peru and 33 days in Chile. Average age of juvenile is about 3 months with 86 days in Costa Rica, 84 days in Peru and 88 days in Chile. There were seven kinds of checks within the statolith, the formation of which might result from endogenous rhythm (such as hatching, mating and spawning) or external stress (such as thermal shock and attacking from predator). In addition, we also found several abnormal structures (such as additional focus, increment and center) and aberrant increment growth pattern in a few statoliths, which was believed to be the result of the damage of statolith caused by external stress.