齐口裂腹鱼耳石早期生长发育与日轮特征研究

文章研究了在实验室条件下齐口裂腹鱼仔稚鱼耳石早期形态发育与生长特点、第一轮纹出现时间和轮纹沉积规律。结果表明: 在13.5-17.2℃孵化条件下,微耳石和矢耳石在出膜前形成,而星耳石于出膜后第12天出现。在仔稚鱼生长过程中,微耳石由近圆形发育成贻贝形,矢耳石经历近圆形、锲形后发育为箭矢状,星耳石形状由近圆形发育为星芒状。微耳石的前区、背区和腹区及矢耳石的背区和腹区生长呈幂函数关系,而微耳石的后区、矢耳石前区和后区生长以及两对耳石的前后区半径之和与全长均呈线性相关。在(18.50.5)℃和(15.61.1)℃条件下,50%矢耳石样本第一轮纹均在出膜后第 2 天形成(分别为出膜后18h和19h),以后每天形成一轮。微耳石和矢耳石轮纹数均与日龄呈线性相关,方程斜率均与1差异不显著(P0.05),表明两对耳石的轮纹沉积均为日周期性。这些结果为研究齐口裂腹鱼野生种群繁殖期和早期生活史特征等生态学问题提供了重要依据。

STUDIES ON THE ONTOGENY,GROWTH AND DAILY INCREMENT OF OTOLITHS IN LARVAE AND JUVENILES OF SCHIZOTHORAX PRENANTI

We performed observation and analysis on the development of the otoliths of larvae and juveniles of Schizothorax prenanti in the laboratory from 2013 to 2014. The procedures were carried out at the hatching temperature 13.5-17.2℃. Lapilli and sagittae formed before hatching, and the asteriscus first appeared on the 12th day post hatching (DPH 12). Lapilli and sagittae had rounded shapes at hatching. As developed the shape of lapilli finally changed into reniform, whereas sagittae became wedge-shaped, the long ellipse shape, and eventually changed into long pointed posterior. The shape of the asteriscus remained mussel-like during the development. The growth of the anterior, dorsal and ventral areas of lapilli, and ventral and dorsal areas of sagittae showed an exponential pattern. The growth of the posterior area of lapilli, and the anterior and posterior areas of sagittae was linear. Furthermore, the summed length of anterior and posterior radius in sagittae and lapilli were linearly related to the total length of the larvae and juveniles. The first increment on the sagittae of larvae appeared on DPH 2 (18 hours post hatching and 19 hours post hatching) at (18.50.5)℃ and (15.61.1)℃. Then one more increment of lapilli and sagittae was formed each day. The number of increments on lapilli and sagittae was linearly related to the age, and the slopes of the equations were close to 1.0 (P0.05). These results demonstrated a daily formation of otoliths increments. Furthermore, our study provided more clues on the ecological characteristics of Schizothorax prenanti, including breeding seasons and the development at early stage.