Examining the Effects of Stocking Density and Depth on Growth of Intensive Cultured Abalone,Haliotis Diversicolor Supertexta Lischke

Abstract

本實驗主在調查鹽度對黑鯛卵發育的影響。我們在黑鯛受精卵發育至不同發生期時，將其移到不同鹽度的海水中，經由孵化時間（僅量初桑椹胚期之卵）、總孵化率及正常孵化率的比較來了解鹽度對卵發育的影響。結果顯示，大致上卵孵化時間會隨鹽度增加而縮短。總孵化率方面，在低鹽度如5及10 ppt下，發生較晚期才轉移的卵通常比較前期轉移的卵有較高的總孵化率，不過除了在眼胞期轉移的卵外，大部份的卵在如此低的鹽度下的正常孵化率都相當低。因此，要得到高正常孵化率所需的鹽度範圍顯然要比得到高總孵化率所需的鹽度範圍來得狹窄。在原腸中期的卵對鹽度變化的敏感性是六組中最高，要得到70％以上正常孵化率的鹽度範圍僅在20至30 ppt之間。This study is to investigate the effects of salinity on egg development of black porgy,Acanthopagrus schlegeli.Fertilized eggs were initially incubated in 35 ppt sea water.Then,embryos from each of six development stages were putted in sea water with salinities ranging from 5 to 45 ppt until they became larvae.The hatching time(only in the eggsat early morula stage),total hatching rate and normal hatching rate were recorded to determine the effect of salinity on eggs.The result indicated that the hatching time of eggsgenerally decreased with increasing salinity.Under low salinity(＜15 ppt),embryos transferred at later stages had higher total hatching rates than those transferred at earlystages.Moreover,most embryos had low viability under low salinity,except for thosetransferred at optical vesicle formation stage.The salinity range was stricter for highviable hatching rate than for high total hatching rate.Embryos from middle gastrula stagewere most sensitive to salinity shift.They had normal hatching rate higher than 70% onlyunder the salinity of 20-30 ppt.