斑鰶仔、稚鱼形态发育及异速生长模式研究

MORPHOLOGICAL DEVELOPMENT AND ALLOMETRIC GROWTH PATTERN OF KONOSIRUS PUNCTATUS AT LARVAE AND JUVENILE STAGES

运用光学显微镜技术和实验生态学方法,对斑鰶(Konosirus punctatus)早期形态发育观察、异速生长模式及其生态学意义进行了研究。结果表明:在水温(21.5±0.5)℃下,初孵仔鱼全长(3.18±0.52)mm,斑鰶仔鱼期从孵化出膜到43日龄棱鳞开始出现前,稚鱼期从44日龄棱鳞出现到55日龄全身覆满鳞片。斑鰶的形态变化和器官分化主要发生在仔鱼期。斑鰶的吻长、躯干长、肠道长、胸鳍长、腹鳍长等重要形态学指标均存在异速生长现象,其生长拐点依次为42日龄(TL:26.41 mm)、24日龄(TL:15.57 mm)、31日龄(TL:21.41 mm)、41日龄(TL:25.47 mm)、42日龄(TL:26.41 mm)。相对于全长、吻长和胸鳍长在拐点前后由正异速生长变为等速生长,腹鳍长由正异速生长转为负异速生长,这为呼吸、摄食和成功逃避捕食者提供有利条件;而肠道长由负异速生长变为等速生长,这可能与斑鰶的食性转化有关。综上所述,为适应复杂多变的生存环境,斑鰶在早期发育阶段优先发育对生长生存起关键作用的器官,这对提高仔、稚鱼的存活率具有重要的生态学意义。研究将为今后进一步人工繁育和苗种培育提供理论依据。

This study investigated the morphological development and allometric growth pattern in early life cycle of Konosirus punctatus and illustrated their crucial ecological meanings for survival.Results showed that the average total length of larvae fish was(3.18±0.52)mm with water temperature at(21.5±0.5)℃.The morphological development of K.punctatus was divided into larvae stage(0—43 day age,from hatching to keeled scales appearing)and fry stage(44—55 day age,from keeled scales appearing to scales covering the body).Morphological changes and organ differentiations mainly occurred in the larval stage.Key morphological characteristics including rostrum length,trunk length,intestinal length,pectoral length and pelvic fin length exhibited allometric growth patterns,in which the growth inflexion point were 42 day age(TL:25.47 mm),24 day age(TL:15.57 mm),31 day age(TL:21.41 mm),41 day age(TL:25.47 mm),42 day age(26.41 mm),respectively.The growth rate in rostrum length and pectoral length changed from the positive allometry(before inflexion point)to the same rate(after inflexion point);the growth rate in pelvic fin length changed from the positive allometry to the negative allometry.These variations could enhance the capacities of breathing,feeding and escaping.The growth rate in intestinal length changed from negative allometry to the same rate,which is related to the dietary conversion of K.punctatus.To adapt to the complex environments,key organs involved in growth and survival were preferentially developed at the early stage,which facilitated the survival rate of K.punctatus.All the findings provide a fundamental evidence for artificial breeding and seedling cultivation in the future.