Abstract:
The purose of this research was to development a technique for rearing eyster Crassostrea belcheri (Sowerby, 1871) broodstock. The study consisted of two parts, namely, the investigation of the oyster's basic physiology and the use of baolinite to broodstock assimilation efficiency and gut resident time. Physiological studies included the effect of salinity (15,20,25 and 30 ppt.) on clearance, respiration and ammonia excretion.The results showed significant differences.(n=30) where lowest and highest clearance rate at 15 ppt was 3.25+-0.26 l/hr and at 25 ppt was 4.74+-0.25 l/hr respectively. Oxygen consumption rate was lowest (1.75+-0.19 Ug-at/l/hr) at 15 ppt salinity and highest (2.90+-0.16 Ug-at/l/hr) at 25 ppt salinity. Ammonia excretion rate were lowest (0.20+-0.01 mg/l/hr) at 25 ppt and highest (0.27+-0.02 mg/l/hour) at 30 ppt salinity. Oyster gut resident time was approximately 29+-0.52 min, at a psecudofeces threshold concentration of approximately 100,000 cells/ml. The effect of kaolinite on assimilation efficiency showed that kaolinite concentrations increased in assimilation efficiency to 78.8% and 85.6% at 50 and 200 mg/l concentration, respectively. ut residence time when fed kaolinite was extended to approximately 40 min. Cultivation of oysters fed kaolinite plus Chaetoceros sp at 100,000 cells/ml, showed more rapid gamete development than oysters fied algae only with statistical significance (p<=.05)