Effects of temperature and salinity were investigated on physiological responses of Mytilus coruscus seedlings. Temperature tolerance and survival of M. coruscus, were examined at temperature 20, 25, 28, 30 and 35$^{circ}C$ for 9 das. Survival of M. coruscus was 90% at temperature 2$0^{circ}C$ and $25^{circ}C$. LT$_{50}$ (lethal temperature) of 9 days was at 27.1$^{circ}C$. The respiration and filtration rates of M. coruscus were increased with temperature up to $25^{circ}C$, and decreased with temperature ranged from $25^{circ}C$ to 3$0^{circ}C$. LS$_{50}$ (lethal salinity, psu) of 9 days at 1$0^{circ}C$, 15$^{circ}C$ and $25^{circ}C$ were 17.01 psu, 19.95 psu and 21.79 psu respectively. Salinity affected survival of M. coruscus with higher temperature. However the respiration and filtration rates were reduced with lower salinity.