Salinity Tolerance and Oxygen Uptake in Initial Developmental Stages of Callinectes rathbunae Contreras and Callinectes sapidus Rathbun (Decapoda: Portunidae)

Initial development stages of Callinectes rathbunae Contreras, 1930 and C. sapidus Rathbun, 1896 experience broad salinity gradients in estuarine landscapes that can affect survival and growth. Salinity tolerance of the megalopa stage and oxygen uptake of four early life stages of these species were estimated at salinity 5, 15, 25 and 35 psu treatments at 25C in the laboratory conditions showing similar salinity tolerances in the megalopa stage. Oxygen uptake rates were greater in low salinities with 9.649531.32278 mol O2 g-1 h-1 for C. rathbunae and 18.789060.55457 mol O2 g-1 h-1 for C. sapidus exposed to 5 psu and decreased in high salinities with 3.682500.37689 C. rathbunae and 8.209381.10001 mol O2 g-1 h-1 for C. sapidus to 35 psu in megalopae stage. Oxygen uptake decreased as they developed and metamorphosed over time. These data are comparable to field distribution and abundances observed in Alvarado Lagoon, Mexico and suggests that tolerance of low salinity (survival and growth) is fueled by greater oxygen uptake rates.