低盐度海水对企鹅珍珠贝存活的影响

Effects of Lower Salinity on Survival of Wing Oyster Pteria penguin

对企鹅珍珠贝稚贝、中贝和成贝在降低盐度的海水中存活状态进行了观察和研究.在水温20～23℃,以不同盐度梯度(8、12、16、20、24、28、30和33)的海水暂养稚贝并定时检查,在广东的四个海区,对盐度变化时中贝及成贝的养殖成活率进行了观察.结果表明:盐度低于16的3个组,稚贝在60h内全部死亡,盐度20～24海水中,稚贝虽只有部分死亡,但活力较差;稚贝在14的海水中4h后转入正常海水,可全部存活,而超过8h后再移入正常海水的稚贝会陆续死亡;在盐度18海水中,稚贝一直未分泌足丝附着,而移入正常海水,6 h就有小苗附着;大万山岛附近海域在雨季盐度可降至20以下,6～9月不适合养殖,而其它实验点可以通过深吊避免海水盐度变化造成企鹅珍珠贝死亡.

The experiments were carried out to study the effects of lower salinity on the survival of juveniles, young and adult wing oyster Pteria penguin. At seawater temperature between 20 - 23℃, the juveniles were reared in seawater of salinity of 8, 12, 16, 20, 24, 28, 30 and 33, the situation was observed at ceitain interval. The results showed that all the juveniles died within 60h when they immersed in the seawater of salinity lower than 16, when in seawater of 20 - 24, partial juveniles died while others were alive but with lower vitality; all juveniles revived after immersed in the seawater of salinity lower than 14 for 4 hrs and then transferred into normal seawater of salinity 33, but when the immersing time prolonged to more than 8 hrs, the spats would die eventually. For the period in the seawater of 18, no juvenile was found fixed, but some were found fixed within 6 hrs after transferred into normal seawater. During March to November of 2003, experiments were arranged to investigate the survival of young and adult wing oyster in 4 different maritime regions, which are Liusha Harbor of Leizhou City, Dongping Pearl Bay of Yang, jiang City, Dawanshan Island and Zhuwantou Island of Zhuhai City, Cuangdong Province. The results from the observations of salinity fluctuation and survival rate of young and adult oysters at these sites primarily indicated that the water salinity near Dawanshan Island might fall down to below 20, which would not be suitable for wing oyster culture during rainy season from June to September, while other 3 waters were adaptable for culturing the wing oyster by lower the water depth to avoid the harm of lower salinity.