SURVIVAL, HEMOLYMPH OSMOLALITY AND TISSUE WATER OF PENAEUS-CHINENSIS JUVENILES ACCLIMATED TO DIFFERENT SALINITY AND TEMPERATURE LEVELS

Survival, growth, haemolymph osmolality and tissue water of Penaeus chinensis (Osbeck) juveniles (0.11 +/- 0.04 g) were investigated, after they were acclimated to 10, 20, 30 and 40 ppt from 33 ppt for 14 days at 24 degrees C, and then acclimated to 12, 18, 24 and 30 degrees C at each salinity for 14 days. The survival of shrimp was the lowest at 10 ppt and 12 degrees C, Growth of shrimp increased with increased temperature in the range 12-24 degrees C, with no significant difference among four salinity levels at 18, 24 and 30 degrees C, Haemolymph osmolality increased with increased salinity, and decreased with increased temperature, The isosmotic point computed from the linear relationship between haemolymph osmolality and medium osmolality was 664, 632, 629 and 602 mOsm/kg which is equivalent to 25.2, 24.1, 24.0 and 23.1 ppt at 12, 18, 24 and 30 degrees C, respectively. Tissue water decreased with increased medium osmolality and haemolymph osmolality. The slope obtained from the relationship between haemolymph osmolality and medium osmolality indicated that there is an impairment of osmoregulatory ability for the P. chinensis juveniles at 12 degrees C.