Meeting Abstract

91.1  Saturday, Jan. 7  Exposure to hypoxia impacts hexapedal locomotion in the blue crab, Callinectes sapidus Rathbun STOVER, KK*; BURNETT, LE; MCELROY, EJ; BURNETT, KG; College of Charleston; College of Charleston; College of Charleston; College of Charleston

The Atlantic blue crab, Callinectes sapidus (Rathbun), is an important commercial and recreational fishing species that resides in the estuarine waters of the Atlantic Ocean and Gulf of Mexico. These highly mobile crustaceans must locomote to find food, evade predators, find a mate and avoid adverse conditions such as hypoxia. In effect, maintaining continuous activity and resisting fatigue for extended periods of time may be necessary for the daily survival of blue crabs. Previous studies on hexapod locomotion have focused on forward-moving cockroaches; while work on crab locomotion has concentrated on terrestrial species utilizing 8 limbs. In this study we tested the effects of 2 levels of hypoxia (4 kPa, 20% air saturation; 10.4 kPa, 50% air saturation) on fatigue during sustained continuous exercise. Fatigue was induced by an exercise trial that entailed continuous sideways hexapedal walking on an underwater treadmill. Fatigue was quantified as the percent decrease in holding performance, which was assessed with a repeated hold force test that mimics the way a male holds a female during mate guarding. Fatigue was defined as a 33% decrease in hold force from pre-exercise values. Fatigue was reached after 6 h of walking for crabs in normoxic seawater, 4 h in 50% air saturation and 2 h in 20% air saturation. Fatigue-resisting behaviors (180˚ turns, stopping and riding to the end) increased from the initial time point by 0.9 behaviors per h in normoxia, 4.1 in 50% air saturation, and 13.8 in 20% air saturation. The force and behavioral results indicate that performance is decreased and fatigue is reached more quickly as the level of hypoxia intensifies. (NSF IOS-0725245)