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Suárez-Pérez A, Orós J. Iatrogenic gas embolism in a juvenile loggerhead sea turtle (Caretta caretta). J Comp Pathol 2024; 208:50-53. [PMID: 38194723 DOI: 10.1016/j.jcpa.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 09/03/2023] [Accepted: 12/08/2023] [Indexed: 01/11/2024]
Abstract
A mild pneumocoelom was diagnosed by computed tomography in a stranded juvenile loggerhead sea turtle (Caretta caretta). After gas extraction by ultrasound-guided puncture, the animal did not improve and was subjected to hyperbaric oxygen therapy (HBOT). After HBOT, the turtle developed marked subcutaneous emphysema and was found dead the following morning. Gross lesions included a distended right atrium with numerous gas bubbles within the epicardium, gas bubbles in the hepatic, gastric and mesenteric veins, a small gas-filled bulla in the left lung and diffuse haemorrhages in the encephalon. Histological lesions included gas-like emboli in the lumen of the right atrium with myocardial necrosis, gas-like emboli in the lumina of intestinal, pulmonary and renal blood vessels and severe meningeal haemorrhages. From a forensic pathology perspective, the subcutaneous emphysema of immediate onset after HBOT and the greater severity of the histological lesions in blood vessels, heart, lung and brain differentiate this case from other cases of gas embolism in turtles due to incidental capture. Two factors contributed to this outcome: the existence of a probably unresolved pneumocoelom and the application of HBOT without an initial diagnosis that accurately indicated its use. Therefore, as in human medicine, the use of HBOT in sea turtles with lung lesions and pneumocoelom is discouraged. This is the first description of an iatrogenic gas embolism in a sea turtle.
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Affiliation(s)
- Alejandro Suárez-Pérez
- Tafira Wildlife Rehabilitation Center, Tafira Baja, 35017 Las Palmas de Gran Canaria, Spain.
| | - Jorge Orós
- Department of Morphology, Veterinary Faculty, University of Las Palmas de Gran Canaria, Trasmontana s/n. 35413 Arucas, Las Palmas de Gran Canaria, Spain
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Robinson NJ, García-Párraga D, Stacy BA, Costidis AM, Blanco GS, Clyde-Brockway CE, Haas HL, Harms CA, Patel SH, Stacy NI, Fahlman A. A Baseline Model For Estimating the Risk of Gas Embolism in Sea Turtles During Routine Dives. Front Physiol 2021; 12:678555. [PMID: 34539425 PMCID: PMC8440993 DOI: 10.3389/fphys.2021.678555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
Sea turtles, like other air-breathing diving vertebrates, commonly experience significant gas embolism (GE) when incidentally caught at depth in fishing gear and brought to the surface. To better understand why sea turtles develop GE, we built a mathematical model to estimate partial pressures of N2 (PN2), O2 (PO2), and CO2 (PCO2) in the major body-compartments of diving loggerheads (Caretta caretta), leatherbacks (Dermochelys coriacea), and green turtles (Chelonia mydas). This model was adapted from a published model for estimating gas dynamics in marine mammals and penguins. To parameterize the sea turtle model, we used values gleaned from previously published literature and 22 necropsies. Next, we applied this model to data collected from free-roaming individuals of the three study species. Finally, we varied body-condition and cardiac output within the model to see how these factors affected the risk of GE. Our model suggests that cardiac output likely plays a significant role in the modulation of GE, especially in the deeper diving leatherback turtles. This baseline model also indicates that even during routine diving behavior, sea turtles are at high risk of GE. This likely means that turtles have additional behavioral, anatomical, and/or physiologic adaptions that serve to reduce the probability of GE but were not incorporated in this model. Identifying these adaptations and incorporating them into future iterations of this model will further reveal the factors driving GE in sea turtles.
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Affiliation(s)
- Nathan J. Robinson
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
| | - Daniel García-Párraga
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
| | - Brian A. Stacy
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources, University of Florida (duty station), Washington, DC, United States
| | | | - Gabriela S. Blanco
- Instituto de Biología de Organismos Marinos (IBIOMAR-CCT CONICET-CENPAT), Puerto Madryn, Argentina
| | | | - Heather L. Haas
- Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Woods Hole, MA, United States
| | - Craig A. Harms
- Department of Clinical Sciences and Center for Marine Sciences and Technology, North Carolina State University, Raleigh, NC, United States
| | - Samir H. Patel
- Coonamessett Farm Foundation, East Falmouth, MA, United States
| | - Nicole I. Stacy
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States
| | - Andreas Fahlman
- Department of Research, Fundación Oceanogràfic de la Comunidad Valenciana, Valencia, Spain
- Global Diving Research, Inc., Ottawa, ON, Canada
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Favilla AB, Costa DP. Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.555509] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Filogonio R, Sartori MR, Morgensen S, Tavares D, Campos R, Abe AS, Taylor EW, Rodrigues GJ, De Nucci G, Simonsen U, Leite CAC, Wang T. Cholinergic regulation along the pulmonary arterial tree of the South American rattlesnake: vascular reactivity, muscarinic receptors, and vagal innervation. Am J Physiol Regul Integr Comp Physiol 2020; 319:R156-R170. [DOI: 10.1152/ajpregu.00310.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Vascular tone in the reptilian pulmonary vasculature is primarily under cholinergic, muscarinic control exerted via the vagus nerve. This control has been ascribed to a sphincter located at the arterial outflow, but we speculated whether the vascular control in the pulmonary artery is more widespread, such that responses to acetylcholine and electrical stimulation, as well as the expression of muscarinic receptors, are prevalent along its length. Working on the South American rattlesnake ( Crotalus durissus), we studied four different portions of the pulmonary artery (truncus, proximal, distal, and branches). Acetylcholine elicited robust vasoconstriction in the proximal, distal, and branch portions, but the truncus vasodilated. Electrical field stimulation (EFS) caused contractions in all segments, an effect partially blocked by atropine. We identified all five subtypes of muscarinic receptors (M1–M5). The expression of the M1 receptor was largest in the distal end and branches of the pulmonary artery, whereas expression of the muscarinic M3 receptor was markedly larger in the truncus of the pulmonary artery. Application of the neural tracer 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindo-carbocyanine perchlorate (DiI) revealed widespread innervation along the whole pulmonary artery, and retrograde transport of the same tracer indicated two separate locations in the brainstem providing vagal innervation of the pulmonary artery, the medial dorsal motor nucleus of the vagus and a ventro-lateral location, possibly constituting a nucleus ambiguus. These results revealed parasympathetic innervation of a large portion of the pulmonary artery, which is responsible for regulation of vascular conductance in C. durissus, and implied its integration with cardiorespiratory control.
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Affiliation(s)
- Renato Filogonio
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Marina R. Sartori
- Department of Zoology, State University of São Paulo, Rio Claro, São Paulo, Brazil
| | - Susie Morgensen
- Department of Biomedicine, Pulmonary, and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Driele Tavares
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Rafael Campos
- Superior Institute of Biomedical Sciences, Ceará State University, Fortaleza, Brazil
| | - Augusto S. Abe
- Department of Zoology, State University of São Paulo, Rio Claro, São Paulo, Brazil
| | - Edwin W. Taylor
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Gerson J. Rodrigues
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Gilberto De Nucci
- Faculty of Medical Sciences, Department of Pharmacology, University of Campinas, Campinas, Brazil
| | - Ulf Simonsen
- Department of Biomedicine, Pulmonary, and Cardiovascular Pharmacology, Aarhus University, Aarhus, Denmark
| | - Cléo A. C. Leite
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, Brazil
| | - Tobias Wang
- Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark
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On-board study of gas embolism in marine turtles caught in bottom trawl fisheries in the Atlantic Ocean. Sci Rep 2020; 10:5561. [PMID: 32221339 PMCID: PMC7101392 DOI: 10.1038/s41598-020-62355-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 02/28/2020] [Indexed: 11/09/2022] Open
Abstract
Decompression sickness (DCS) was first diagnosed in marine turtles in 2014. After capture in net fisheries, animals typically start showing clinical evidence of DCS hours after being hauled on-board, often dying if untreated. These turtles are normally immediately released without any understanding of subsequent clinical problems or outcome. The objectives of this study were to describe early occurrence and severity of gaseous embolism (GE) and DCS in marine turtles after incidental capture in trawl gear, and to provide estimates of on-board and post-release mortality. Twenty-eight marine turtles were examined on-board fishing vessels. All 20 turtles assessed by ultrasound and/or post-mortem examination developed GE, independent of season, depth and duration of trawl and ascent speed. Gas emboli were obvious by ultrasound within 15 minutes after surfacing and worsened over the course of 2 hours. Blood data were consistent with extreme lactic acidosis, reduced glomerular filtration, and stress. Twelve of 28 (43%) animals died on-board, and 3 of 15 (20%) active turtles released with satellite tags died within 6 days. This is the first empirically-based estimate of on-board and post-release mortality of bycaught marine turtles that has until now been unaccounted for in trawl fisheries not equipped with turtle excluder devices.
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Williams CL, Sato K, Ponganis PJ. Activity, not submergence, explains diving heart rates of captive loggerhead sea turtles. ACTA ACUST UNITED AC 2019; 222:jeb.200824. [PMID: 30936271 DOI: 10.1242/jeb.200824] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 03/26/2019] [Indexed: 11/20/2022]
Abstract
Marine turtles spend their life at sea and can rest on the seafloor for hours. As air-breathers, the breath-hold capacity of marine turtles is a function of oxygen (O2) stores, O2 consumption during dives and hypoxia tolerance. However, some physiological adaptations to diving observed in mammals are absent in marine turtles. This study examined cardiovascular responses in loggerhead sea turtles, which have even fewer adaptations to diving than other marine turtles, but can dive for extended durations. Heart rates (f H) of eight undisturbed loggerhead turtles in shallow tanks were measured using self-contained ECG data loggers under five conditions: spontaneous dives, resting motionless on the tank bottom, resting in shallow water with their head out of water, feeding on squid, and swimming at the surface between dives. There was no significant difference between resting f H while resting on the bottom of the tank, diving or resting in shallow water with their head out of water. f H rose as soon as turtles began to move and was highest between dives when turtles were swimming at the surface. These results suggest cardiovascular responses in captive loggerhead turtles are driven by activity and apneic f H is not reduced by submergence under these conditions.
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Affiliation(s)
- Cassondra L Williams
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, 8655 Kennel Way, La Jolla, CA 92037, USA
| | - Katsufumi Sato
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan
| | - Paul J Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, 8655 Kennel Way, La Jolla, CA 92037, USA
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Joyce W, Axelsson M, Wang T. Contraction of atrial smooth muscle reduces cardiac output in perfused turtle hearts. ACTA ACUST UNITED AC 2019; 222:jeb.199828. [PMID: 30787139 DOI: 10.1242/jeb.199828] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 02/18/2019] [Indexed: 11/20/2022]
Abstract
Unusual undulations in resting tension (tonus waves) were described in isolated atria from freshwater turtles more than a century ago. These tonus waves were soon after married with the histological demonstration of a rich layer of smooth muscle on the luminal side of the atrial wall. Research thereafter waned and the functional significance of this smooth muscle has remained obscure. Here, we provide evidence that contraction of the smooth muscle in the atria may be able to change cardiac output in turtle hearts. In in situ perfused hearts of the red-eared slider turtle (Trachemys scripta elegans), we demonstrated that activation of smooth muscle contraction with histamine (100 nmol kg-1 bolus injected into perfusate) reduced cardiac output by decreasing stroke volume (>50% decrease in both parameters). Conversely, inhibition of smooth muscle contraction with wortmannin (10 µmol l-1 perfusion) approximately doubled baseline stroke volume and cardiac output. We suggest that atrial smooth muscle provides a unique mechanism to control cardiac filling that could be involved in the regulation of stroke volume during diving.
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Affiliation(s)
- William Joyce
- Department of Bioscience, Section for Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Tobias Wang
- Department of Bioscience, Section for Zoophysiology, Aarhus University, 8000 Aarhus C, Denmark.,Aarhus Institute of Advanced Studies, Aarhus University, 8000 Aarhus C, Denmark
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Garcia Párraga D, Moore M, Fahlman A. Pulmonary ventilation-perfusion mismatch: a novel hypothesis for how diving vertebrates may avoid the bends. Proc Biol Sci 2018; 285:20180482. [PMID: 29695441 PMCID: PMC5936736 DOI: 10.1098/rspb.2018.0482] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 03/28/2018] [Indexed: 11/22/2022] Open
Abstract
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 ([Formula: see text]) and cardiac output/lung perfusion ([Formula: see text]), varying the level of [Formula: see text] in different regions of the lung. Man-made disturbances, causing stress, could alter the [Formula: see text] 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.
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Affiliation(s)
| | - Michael Moore
- Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Andreas Fahlman
- Fundación Oceanogràfic, Ciudad de las Artes y las Ciencias, 46013 Valencia, Spain
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