Meeting Abstract
P2.132 Sunday, Jan. 5 15:30 Effects of hypoxia and sub-lethal bacterial injection on critical oxygen pressures of penaeid shrimp SONG, S.M.*; BURNETT, L.E.; BURNETT, K.G.; College of Charleston; College of Charleston; College of Charleston song.sarah@gmail.com
Estuarine organisms such as juvenile penaeid shrimp experience fluctuating O2 pressures on a daily basis. In coastal waters of the southeastern US, severe hypoxia (4-6 kPa) is common in the summer, also a time during which bacterial concentrations in seawater are high. In response to invading bacteria, crustaceans mount an immune defense resulting in aggregation of circulating hemocytes. These aggregates can be trapped in and obstruct hemolymph flow through the gills, inhibiting O2 uptake. Hypoxia itself is also known to inhibit immune function. In this study we compare overall O2 uptake in two commercially important shrimp species following acute exposure to environmental hypoxia, and injection with a sublethal dose of bacteria. Wild-caught Litopenaeus setiferus (Atlantic white shrimp) and aquacultured L. vannamei (Pacific whiteleg shrimp) were held in normoxia (>16 kPa) or hypoxia (~10 kPa) and injected with saline or bacteria (Vibrio campbellii 90-69B3). The rate of O2 uptake and critical O2 pressure (Pcrit), the pressure below which O2 uptake depends on available O2, were measured. Trials with bacterial injections are ongoing; preliminary results of LD50 tests suggest that virulence of V. campbellii in L. setiferus (LD50 = approx. 7.61×105 CFU g–1 shrimp) is similar to that previously determined in L. vannamei (LD50 = 3.06×105 CFU g–1 shrimp). In normoxia, the Pcrit of L. vannamei (3.5 kPa) is lower than that of L. setiferus (6.3 kPa). This is consistent with previous findings in our lab, that hemocyanin in L. vannamei has a higher O2 affinity than that in L. setiferus. These data suggest that L. vannamei is better adapted to hypoxia than L. setiferus. (NSF IOS-1147008)
