Effects of salinity on growth and molting of sympatric Callinectes spp. from Camaronera Lagoon, Veracruz, Mexico

Megalopae of Callinectes rathbunae Contrareras, 1930 and C. sapidus Rathbun, 1896 were exposed to salinities of 5, 15, and 25 at 25.0°C (through crab stage 16) to determine if there were species-specific differences in survival, growth, and intermolt duration. Survival of C. rathbunae decreased significantly at higher salinities, but there was no salinity effect for C. sapidus . Callinectes rathbunae had significantly higher survival than C. sapidus in salinities of 5 and 15, but survival was not different in a salinity of 25. There was no difference in survival of C. rathbunae by gender; survival of both genders was generally lowest at a salinity of 25. There was no difference in survival for females of C. sapidus among salinities, but males had lowest survival at the lowest salinity. Additionally, males had significantly greater survival than females in salinities of 15 and 25. Females of C. rathbunae grew faster than males at all salinities and both genders grew fastest in a salinity of 15. In contrast, males and females of C. sapidus grew at the same rate, with the lowest growth rate for both genders at the lowest salinities. Relative to C. rathbunae , C. sapidus had a significantly higher growth rate and shorter intermolt duration at the highest salinity. There was no significant difference in intermolt duration between genders for C. rathbunae or C. sapidus. However, intermolt duration among salinity treatments for C. rathbunae differed significantly in crabs ≥ stage 7, with the longest duration in the highest salinity. In contrast, intermolt duration of C. sapidus was shortest in a salinity of 25. Results of this study suggest that C. rathbunae is more tolerant of low salinity habitats than C. sapidus.