Dissertation Defence: Acute and Long-Term Influence of Apnea Diving in Mammals
June 2 at 8:00 am - 12:00 pm
Courtney Brown, supervised by Dr. Philip Ainslie, will defend their dissertation titled “Acute and Long-Term Influence of Apnea Diving in Mammals” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Kinesiology.
An abstract for Courtney Brown’s dissertation is included below.
Examinations are open to all members of the campus community as well as the general public. Please email philip.ainslie@ubc.ca to receive the Zoom link for this exam.
Abstract
Despite having a shared common ancestor, marine mammals have undergone millennia of adaptations to become superior divers and endure a semi-aquatic lifestyle. Humans, by contrast, lack these specialized traits. While certain coastal populations have practiced free-diving for generations, competitive free-divers often achieve remarkable feats without such a lineage. Despite extensive research into the mechanisms central to the success of diving, the extent to which key traits are trainable versus inherited remains unresolved. The aim of this dissertation is to expand our understanding on what characteristics pertinent to diving capacity can be expanded through rigorous training and which traits must be selected for. We address this through four studies. First, we investigated the activation of the mammalian dive reflex through assessing the cardiovascular and hematological responses to dry dynamic apnea compared to exercise and static apnea trials. We further examined the potential influences of performance level and sex on these responses. Second, we analyzed hematological responses to apnea in elite human free-divers and northern elephant seals, species that experience apnea routinely. Third, we explored the metabolome across several taxa, comparing elite free-divers, non-diving humans, and deep-diving seals. We ultimately found that performance level had little influence on the magnitude of the cardiovascular and hematological responses to dynamic apnea, suggesting that training has a mild effect on the activation of the mammalian dive reflex in humans. Further, we found the hematological response to static apnea in northern elephant seals as well as the metabolome in northern elephant seals and grey seals tended to suggest enhanced physiological features to help mitigate the stress of diving including enhanced pH buffering as well as elevated antioxidant synthesis and DNA repair. Lastly, we found that Ama divers had comparable gas exchange efficiency as well as similar lung size and function as controls, suggesting that diving does not cause long-term damage to the lungs. Together, these data suggest that although human free-divers achieve physiology defying feats, there are inherent traits in both northern elephant and gray seals that make them superior divers and highly adapted to the marine environment.
