The combined effects of salinity and temperature on the survival and development of zoea, megalopa and crab instar larvae of mud crab, Scylla tranquebarica (Fabricius 1798)

An experiment was carried out to determine the combined effects of temperature and salinity on the survival and development of zoea, megalopa and crab instar stages of mud crab Scylla tranquebarica (Fabricius 1798). Salinities of 15, 25, 35 and 45 ppt were tested for each of the zoea stages; 5, 15, 25, 35, 45 ppt for the megalopae and 0, 5, 15, 25, 35 and 45 ppt for crab instar 1 (C1), at temperatures of 20, 26 and 32 °C. Two-way ANOVA showed a significant effect of temperature, salinity and interaction between temperature and salinity on the survival of all stages tested. Larvae at Z1–Z4 stages tolerated 25-35 ppt in 20 °C and 25–45 ppt in 26 and 32 °C. There was successful metamorphosis of Z5 larvae to megalopa at 25–35 ppt in 26 and 32 °C while all larvae died at 15 and 45 ppt, in all temperatures. The megalopae survived and developed to crab instar at 25–35 ppt in 26 and 32 °C. The first crab instar (C1) survived to the second crab instar (C2) at 5-45 ppt in 26 and 32 °C and at 15–45 ppt in 20 °C.