Abstract
The cetacean respiratory system has undergone diverse and highly specialized anatomical and mechanical adaptations to accommodate a strictly aquatic lifestyle.1,4 In contrast to terrestrial mammals, the cetacean respiratory system is adapted to operate on an inspiratory breath-hold. During a dive, air in the lungs is carefully managed to perform multiple, simultaneous functions, including gas exchange, buoyancy control, echolocation, vocalization and foraging. Because their respiratory system carries out multiple roles, respiratory diseases have the potential to greatly impact a cetacean's ability to thrive in the wild. Since 1999, Cryptococcus gatti has emerged as an endemic fungus to the Pacific Northwest and has resulted in mortality of humans, terrestrial mammals and cetaceans.2,3,5 Our objective is to assess the effects of Cryptococcus gatti on the respiratory system of cetaceans by utilizing pulmonary mechanical techniques. A multi-faceted approach is being utilized to examine structural, biomechanical and pathological differences across species. During necropsy, the lungs from harbor porpoises (Phocoena phocoena), Dall's porpoises (Phocoenoides dalli) and Pacific white-sided dolphins (Lagenorhynchus obliquidens) are excised, and then imaged in three inflated states using computed tomography followed by quasi-static pulmonary mechanics to generate pressure-volume curves. Preliminary results suggest that in severe infections the lungs have a decrease in mass-specific total lung capacity by up to 94%, a four-fold increase in lung mass, and an overall decrease in compliance. In conclusion, pulmonary mechanics is a useful tool for both understanding the normal physiology of diving mammals and assessing the pathophysiology of live and dead stranded marine mammals.
Acknowledgements
The authors wish to thank all staff and volunteers with the British Columbia Marine Mammal Rescue Network (BCMMRN), British Columbia's Department of Fisheries and Oceans (DFO), and Vancouver Aquarium. We also wish to acknowledge technical assistance from Dean Malpas with Canada Diagnostic, Andreas Fahlman, and Dr. Marty Haulena, as well as funding from UBC Graduate Fellowship. Parts collected under DFO and BCMMRN.
* Presenting author
+ Student presenter
Literature Cited
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