Pulmonary ventilation–perfusion mismatch : a novel hypothesis for how diving vertebrates may avoid the bends
Garcia Párraga, Daniel
Moore, Michael J.
MetadataShow full item record
KeywordDiving physiology; Cardiorespiratory physiology; Whale stranding; Noise pollution; Climate change
Hydrostatic lung compression in diving marine mammals, with collapsing alveoli blocking gas exchange at depth, has been the main theoretical basis for limiting N2 uptake and avoiding gas emboli (GE) as they ascend. However, studies of beached and bycaught cetaceans and sea turtles imply that air-breathing marine vertebrates may, under unusual circumstances, develop GE that result in decompression sickness (DCS) symptoms. Theoretical modelling of tissue and blood gas dynamics of breath-hold divers suggests that changes in perfusion and blood flow distribution may also play a significant role. The results from the modelling work suggest that our current understanding of diving physiology in many species is poor, as the models predict blood and tissue N2 levels that would result in severe DCS symptoms (chokes, paralysis and death) in a large fraction of natural dive profiles. In this review, we combine published results from marine mammals and turtles to propose alternative mechanisms for how marine vertebrates control gas exchange in the lung, through management of the pulmonary distribution of alveolar ventilation (Embedded Image) and cardiac output/lung perfusion (Embedded Image), varying the level of Embedded Image in different regions of the lung. Man-made disturbances, causing stress, could alter the Embedded Image mismatch level in the lung, resulting in an abnormally elevated uptake of N2, increasing the risk for GE. Our hypothesis provides avenues for new areas of research, offers an explanation for how sonar exposure may alter physiology causing GE and provides a new mechanism for how air-breathing marine vertebrates usually avoid the diving-related problems observed in human divers.
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Proceedings of the Royal Society B: Biological Sciences 285 (2018): 20180482, doi:10.1098/rspb.2018.0482.
Suggested CitationArticle: Garcia Párraga, Daniel, Moore, Michael J., Fahlman, Andreas, "Pulmonary ventilation–perfusion mismatch : a novel hypothesis for how diving vertebrates may avoid the bends", Proceedings of the Royal Society B: Biological Sciences 285 (2018): 20180482, DOI:10.1098/rspb.2018.0482, https://hdl.handle.net/1912/10310
The following license files are associated with this item:
Showing items related by title, author, creator and subject.
Benz(a)anthracene in benthic marine environments : bioavailability, metabolism, and physiological effects on the polychaete Neries virens McElroy, Anne Elizabeth (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1985-02)The fate of [14C- 121 benz(a)anthracene (BA) was followed in benthic microcosm experiments in the presence and absence of the polychaete Nereis virens. In concert with chemical analysis of BA and its metabolites in all ...
The physiology of dormancy and germination in cysts of the marine dinoflagellate Scrippsiella trochoidea Binder, Brian Jeffrey (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1986-02)Cysts of Scrippsiella trochoidea are representative of the thick-walled non-motile resting cells produced by many dinoflagellates. Although the influence of cysts on the biology and ecology of dinoflagellates may be ...
Orchard, Elizabeth Duncan (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2010-02)Primary producers play a critical role in the oceanic food chain and the global cycling of carbon. The marine diazotroph Trichodesmium is a major contributor to both primary production and nitrogen fixation in the tropical ...