Osmoregulatory Capacity and Ion Regulation of Penaeus monodon Fabricus In Fluctuated Salinity
Changes in salinity parameter cause stressed shrimp and disturbed physiologically. This study was aimed to determine the ability of osmoregulation and ion regulation of juvenile black tiger shrimp P.monodon in fluctuated salinity. Split plot completely randomize design was used with 4 levels of maintenance time as the main plot and the 9 levels of salinity as a subplot with 3 replications. 10 juvenile shrimps weighed 11-14 g were stocked per aquarium 50-35 L. Salinity treatments consist of 25 ppt (isosmotic/initial salinity); 13, 10, 7 and 4 ppt (hypoosmotic); 37, 39, 41 and 43 ppt (hyperosmotic) and maintenance time juvenile were 6, 24, 96, 168 hours. The results showed that salinity, maintenance time and their interaction fluenced the osmolarity both of juvenile hemolymph and media significantly (P<0.01). Highest levels of osmotic (6.572 mOsm/L) was found on hiposmotic media 4 ppt within 24 hours of maintenance and the lowest level (0.467 mOsm/L) was on hyperosmotic media 39 ppt within 168 hours of maintenance. Juvenile shrimp osmotic was not affected by maintenance time significantly (P>0.05), while salinity and the interaction are highly significant (P<0.01). At all maintenance time, survival rate and ions concentration were lower on media 4 ppt than in high alinity. It reflected the loss of osmotic capacity of the shrimp.