Effect of different salinity levels on megalopa Scylla tranquebarica (Fabricius, 1798) rearing to the crablet production

Abstract

The salinity level for the culture of megalopae affects crablet production. The research aimed to determine the optimum salinity level for the megalopa of S. tranquebarica rearing. Nine aquariums randomly selected and filled with sterile seawater, have different salinity levels (A. 29-30 ppt, B. 27-28 ppt, and C. 25-26 ppt) used for megalopae rearing. Each aquarium is stocked with 30 individuals of megalopa. Each treatment with three replications. Crumble pellets and Artemia nauplii are given as feed for megalopae. Monitoring in each treatment consists of total hemocytes, the osmolality of megalopae and water media, osmotic level, Vibrio spp, total bacteria, and crablet production. The osmolality rate of megalopa hemolymph was highest at the salinity of 25-26 ppt. The lowest osmotic level at the salinity of 29-30 ppt. The total bacteria population at salinity 29-30 ppt was lower (p<0.05) than at salinity 27-28 ppt and 25-26 ppt. Consequently, the Vibrio spp population was higher at 29-30 ppt salinity. The total hemocytes of megalopae at a salinity of 27-28 ppt were higher (p<0.05) than the total hemocytes at a salinity of 25-26 ppt and 29-30 ppt. Therefore, the most increased crablet production in the megalopa reared at the salinity of 27 28 ppt.