A multidisciplinary study will examine certain important adaptations of the Weddell seal (Leptonychotes weddelli) which have made it a champion diver able to reach great depths (500m) for long periods (over an hour) in the Antarctic Ocean. Scientists will focus on mechanisms of gas transport in the free diving seal, using non-invasive ultrasonography to evaluate the oxygen storage capacity of the seal's spleen and continuous laser spectrophotometry to study during free diving the role of oxymyoglobin in skeletal muscle oxygen stores. The diversion of oxyhemoglobin to the heart and brain in lieu of the peripheral circulation will be examined. A velocity meter will be perfected to enable an estimate of the metabolic demands in diving seals. These pioneering techniques of microprocessor monitoring of free diving seals were developed by this team on previous Antarctic expeditions. In parallel studies, the heart rate alterations of fetal seals which allow this Antarctic seal to tolerate prolonged periods of hypoxia during diving will be studied. This research project will advance an understanding of how adult and fetal marine mammals dive for prolonged periods.
