盐度对异育银鲫呼吸和氨氮排泄生理的影响

研究了异育银鲫(Carassius auratus gibeliovar. E′erqisi)从淡水向盐度1.5‰、3‰、6‰、9‰、12‰突变与适应过程中的呼吸和氨氮排泄生理的变化规律。结果表明:盐度突变开始时,异育银鲫的耗氧率和排氨率随外界盐度的升高而增大,随盐度作用时间延长,耗氧率和排氨率升到最大值后又开始下降并最终维持在稳定水平,但开始下降的时间和下降的幅度以及最终的稳定水平与外界盐度有关。盐度1.5‰和3‰处理组在作用12h时耗氧率升到最大值,此后下降,于第3天后保持在比淡水对照组略低的稳定水平,但二者差异不显著(P0.05);盐度6‰和9‰处理组在作用到第3天后才开始缓慢下降,并分别于第10、15天时保持在显著高于淡水对照的稳定水平(P0.05);盐度12‰处理组也在第3天后下降,到第10天后保持在比淡水对照组略低的稳定水平,但二者差异不显著(P0.05)。各盐度处理组的排氨率均在盐度作用24h时达到最大值,其中盐度1.5‰处理组的变化不显著(P0.05),其他各组均显著升高(P0.05),并都于第10天时下降到稳定水平,其中盐度3‰处理组的稳定水平略低于对照组(P0.05),盐度6‰、9‰、12‰处理组的稳定水平显著高于对照组(P0.05)。

EFFECTS OF SALINITY ON OXYGEN CONSUMPTION RATE AND AMMONIA EXCRETION RATE OF ALLOGYNOGEMETIC CRUCIAN CARP

Although people usually think that freshwater fish always live and be cultivated well in fresh water, actually,some kinds of freshwater fish also can survive even live better and grow faster in the waters which contain certain salinity than those in fresh water. As filial generation of Carassius auratus gibelio (female parent) and Cyprinus carpio singuonensis (male parent) by allogynogenesis, allogynogemetic crucian carp is regarded as a typical freshwater fish which grows rapidly in waters of less than 0.5‰ salinity. Because it grows faster than its female parent and tastes more delicious than its male parent, it is popular with people and has become an important breed cultivated in fresh water. In addition, it has advantages in adaptability and has been cultivated largely in ponds excavated on some soline-alkali soil or littoral. However, there are not any theories which can tell people what kinds of pond are suitable to cultivate allogynogemetic crucian carps efficiently and safely, and this leads to low benefits and high danger. In order to avoid these possible defects and guide people to cultivate allogynogemetic crucian carps in scientific way, the rules of the metabolic rate changes of allogynogemetic crucian carp were investigated when the salinity changed abruptly from freshwater to 1.5‰, 3‰, 6‰, 9‰ and 12‰ respectively. Oxygen consumption rate was measured by the method of Winkler's iodometry, and ammonia excretion rate was determined with the sodium hypobromite oxidation method. The results showed that the oxygen consumption rate and ammonia excretion rate of allogynogemetic crucian carp increased with the rise of salinity. The level of oxygen consumption rate got to the peak at the 12h of the experiment, and then went down slowly. The oxygen consumption rate in salinity of 1.5‰ and 3‰ preserved lower level than the freshwater group at the 3d, but not distinctly (P>0.05). However, the salinity of 6‰ and 9‰ groups came down after the 3d and retained higher stable level than the control group distinctly at the 10d and 15d (P<0.05). The salinity of 12‰ group also came down after the 3d, but it kept at lower level than the control group, not distinctly at the 10d (P>0.05). The ammonia excretion rate of all treatments reached the peak level at the 24h of the experiment. Only the ammonia excretion rate salinity of 1.5‰ changed not prominence (P>0.05), the others rose notably (P<0.05), and went down at the 10d.The ammonia excretion rate salinity of 3‰ remained at lower level than the control group but not distinctly (P>0.05),and the salinity of 6‰, 9‰ and 12‰ retained higher stable level than the control group distinctly (P<0.05). Therefore,the results indicate that energy consumption and nitrogen metaboly of allogynogemetic crucian carp are the lowest when the salinity of water is 3‰, and it is likely to be the optimal salinity for allogynogemetic crucian carp.