The effects of salinity on survival and food intake in mantis shrimp Oratosquilla oratoria larvae

A series of trials was conducted to study effects of gradual and abrupt changes in salinity on survival and food intake in pseudozoea(Z9-Z11) of mantis shrimp(Oratosquilla oratoria)in a laboratory.The pseudozoea were directly exposed to a salinity of 51,48,45,42,39,36,33,30,24,21,18,15,12,and 9 from a salinity of 27,or gradually increased to the salinity from 33 and decreased from 24,at a rate of 1 in a 12 h interval until all pseudozoea died.The pseudozoea were fed fresh opossum shrimp(body length from 5.19 to 8.91 mm and body weight of 0.058 g).The results showed that the pseudozoea had survival rate of more than 77.8% when they were suddenly exposed to a salinity of 18-36 from initial salinity of 27,with 24 h median lethal salinity(MLS) of 15.94 at a salinity of 18 and 41.13 at salinity of 36.During the sudden change,the high salinity limit for the pseudozoea was 48,and the low salinity limit 12.During the gradual change,the pseudozoea tolerated the salinity ranging from 6 to 54.The pseudozoea almost stopped feeding at a salinity of lower than 15 or higher than 45,feeding significantly more food at a salinity of 27,30 and 33 than at other salinity.Thus,the Z9-Z11 pseudozoea was found to be cultivated in the water with a salinity of 27-33 for survival rate and food intake.