尼罗罗非鱼(Oreochromis nilotica Linn)幼鱼渗透压调节的初步研究

PRELIMINARY STUDIES OF OSMOTIC REGULATION IN THE JUVENILE OREOCHROMIS NILOTICA (LINN)

作者提出了放置于水温为19～20℃及30℃,盐度为0,16‰和30‰的各水体中尼罗罗非鱼渗透压调节的时间过程。研究揭示出尼罗罗非鱼幼鱼具有极其灵活的渗透压调节能力力:当水体由于盐度的改变,其冰点下降值Δ°改变114～121.4％时,幼鱼在收容五天后,血液渗透压重新达到平衡,冰点下降值Δ°只增加1.6～4.7％,当水体的Δ°改变292～307.2％,幼鱼血液渗透压的Δ°值只增加4.7～6.2％。作者认为,该幼鱼渗透压的调节过程分为三个阶段,一、失控期,Δ°值迅速增加 二,调节期,Δ°缓慢地随收容时间继续增加,直达到最大值,并开始下降;三、趋平期,幼鱼血液的Δ°值下降并达到平衡位置。尼罗罗非鱼渗透压调节的具体时间过程及特点取决于其内外渗透浓度变化的梯度(从淡水到海水或半海水)以及水温、饵料条件。

The present paper examines the time course of the osmotic adjustment in the Oreochromis nilotica (Linn) exposed to various water temperatures of 19-20℃ and30℃. The study reveals that Oreochromis nilotica (Linn) has considerable flexibility in osmotic adjustment ability. When the △° of water is altered by 114-121 % as a result of the change of ambient salinity, the △° of blood of the young fish attains to equilibrium after five days of exposure with an increase of only 1. 6-4.3%. When the △° of water is altered by 292-307. 2%, the △° of blood of the young fish increases only by 4. 7 -6. 2%.Temporarily,the osmotic adjustment process can be divided into three phases. Firstly, it is an uncontrollable period, having a rapid increase in △° The second is a regulation period, during which the △° increases slowly as exposure continues, until a maximum value is reached, and starts to decrease afterwards. The third one is a period trending toward equilibrium The A of blood of the young fish decreases and attains to equilibrium. Concrete time course of the osmotic adjustment of the Orcochromis nilotica and its characters depend on the variation of gradient between the internal and external osmotic concentration (from freshwater into marine or semimarine water), on water temperature and food conditions.