{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T23:40:20Z","timestamp":1790293220038,"version":"4.1.0"},"reference-count":26,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,7,2]],"date-time":"2025-07-02T00:00:00Z","timestamp":1751414400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Physiol."],"abstract":"<jats:p>Reproductive processes place significant physiological demands on animals, often accompanied by hormonal and neural changes. In this study, we examined changes in heart rate of gravid loggerhead turtles (C<jats:italic>aretta caretta<\/jats:italic>) during nesting activities on the beach, especially during egg-laying phase. To examine heart rate throughout the nesting activities, non-invasive electrocardiogram (ECG) loggers and accelerometers were deployed on five gravid females. Heart rate increased markedly upon beach landing and remained elevated during most nesting phases. However, a significant decrease in heart rate, often accompanied by increased RMSSD, was observed during egg-laying, suggesting parasympathetic nervous system dominance during this phase. This pattern is similar to observation reported in other species (e.g., horses and chum salmon), where bradycardia during reproductive events is associated with elevated parasympathetic tone. Our study reported an apparent reduction in heart rate during oviposition, which reflects the physiological mechanisms underlying nesting activities in sea turtles, and suggest that external stressors disrupting parasympathetic activity may reduce egg-laying success.<\/jats:p>","DOI":"10.3389\/fphys.2025.1540252","type":"journal-article","created":{"date-parts":[[2025,7,2]],"date-time":"2025-07-02T05:52:58Z","timestamp":1751435578000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Apparent reduction in heart rate during oviposition revealed by non-invasive heart rate monitoring of gravid loggerhead turtles"],"prefix":"10.3389","volume":"16","author":[{"given":"Tomoko","family":"Narazaki","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masanori","family":"Mori","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshimasa","family":"Matsuzawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ayaka","family":"Saito","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chihiro","family":"Kinoshita","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masanori","family":"Kurita","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kensuke","family":"Matsumiya","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hikari","family":"Okada","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kentaro Q.","family":"Sakamoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,7,2]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1917","DOI":"10.1242\/jeb.205.13.1917","article-title":"The relationship between heart rate of oxygen consumption in Galapagos marine iguanas (Amblyrhynchus cristatus) at two different temperatures","volume":"205","author":"Butler","year":"2002","journal-title":"J. Exp. Biol."},{"key":"B2","doi-asserted-by":"publisher","first-page":"95","DOI":"10.1016\/j.biocon.2006.05.019","article-title":"Physiological and reproductive consequences of human disturbance in humboldt penguins: the need for species-specific visitor management","volume":"133","author":"Ellenberg","year":"2006","journal-title":"Biol. Conserv."},{"key":"B3","doi-asserted-by":"publisher","first-page":"315","DOI":"10.1007\/bf00709998","article-title":"Ventilation and gas exchange during rest and exercise in adult green sea turtles","volume":"134","author":"Jackson","year":"1979","journal-title":"J. Comp. Physiol."},{"key":"B4","doi-asserted-by":"publisher","first-page":"253","DOI":"10.1016\/j.jembe.2004.03.005","article-title":"Hormonal and metabolic responses to nesting activities in the green turtle, Chelonia mydas","volume":"308","author":"Jessop","year":"2004","journal-title":"J. Exp. Mar. Biol. Ecol."},{"key":"B5","doi-asserted-by":"publisher","first-page":"811947","DOI":"10.3389\/fphys.2022.811947","article-title":"A non-invasive heart rate measurement method is improved by placing the electrodes on the ventral side rather than the dorsal in loggerhead turtles","volume":"13","author":"Kinoshita","year":"2022","journal-title":"Front. Physiol."},{"key":"B6","doi-asserted-by":"publisher","first-page":"21748","DOI":"10.1038\/s41598-024-72521-w","article-title":"A feasibility study on predicting cow calving time over 40h in advance using heart rate and financial technical indicators","volume":"14","author":"Kishi","year":"2024","journal-title":"Sci. Rep."},{"key":"B7","doi-asserted-by":"publisher","first-page":"281","DOI":"10.1016\/j.physbeh.2014.11.039","article-title":"Heart rate and heart rate variability in multiparous dairy cows with unassisted calvings in the periparturient period","volume":"129","author":"Kov\u00e1cs","year":"2015","journal-title":"Physiol. Behav."},{"key":"B8","first-page":"277","article-title":"Diving physiology","volume-title":"The biology of sea turtles","author":"Lutcavage","year":"1997"},{"key":"B9","doi-asserted-by":"publisher","first-page":"e5993","DOI":"10.1371\/journal.pone.0005993","article-title":"Cardiac arrest during gamete release in chum salmon regulated by the parasympathetic nerve system","volume":"4","author":"Makiguchi","year":"2009","journal-title":"PLoS ONE"},{"key":"B10","doi-asserted-by":"publisher","first-page":"e44986","DOI":"10.7554\/eLife.44986","article-title":"Reduced metabolism supports hypoxic flight in the high-flying bar-headed goose (Anser indicus)","volume":"8","author":"Meir","year":"2019","journal-title":"eLife"},{"key":"B11","first-page":"51","article-title":"Reproduction in sea turtles","volume-title":"The biology of sea turtles","author":"Miller","year":"1997"},{"key":"B12","doi-asserted-by":"publisher","first-page":"160","DOI":"10.1016\/j.theriogenology.2014.03.015","article-title":"Parturition in horses is dominated by parasympathetic activity of the autonomous nervous system","volume":"82","author":"Nagel","year":"2014","journal-title":"Theriogenology"},{"key":"B13","doi-asserted-by":"publisher","first-page":"bio049247","DOI":"10.1242\/bio.049247","article-title":"Heart rate and cardiac response to exercise during voluntary dives in captive sea turtles (cheloniidae)","volume":"9","author":"Okuyama","year":"2020","journal-title":"Biol. Open"},{"key":"B14","first-page":"315","article-title":"Hormones in the life history of sea turtles","volume-title":"The biology of sea turtles","author":"Owens","year":"1997"},{"key":"B15","doi-asserted-by":"publisher","first-page":"9","DOI":"10.1007\/s003600050042","article-title":"Heart rate and plasma lactate responses during submerged swimming and trained diving in California sea lions, Zalophus californianus","volume":"167","author":"Ponganis","year":"1997","journal-title":"J. Comp. Physiol. B"},{"key":"B16","doi-asserted-by":"publisher","first-page":"jeb243922","DOI":"10.1242\/jeb243922","article-title":"Effects of a parasympathetic blocker on the heart rate of loggerhead sea turtles during voluntary diving","volume":"225","author":"Saito","year":"2022","journal-title":"J. Exp. Biol."},{"key":"B17","doi-asserted-by":"publisher","first-page":"jeb246334","DOI":"10.1242\/jeb.246334","article-title":"Heart rate reduction during voluntary deep diving in free-ranging loggerhead sea turtles","volume":"227","author":"Saito","year":"2024","journal-title":"J. Exp. Biol."},{"key":"B18","doi-asserted-by":"publisher","first-page":"20200222","DOI":"10.1098\/rstb.2020.0222","article-title":"A non-invasive system to measure heart rate in hard-shelled sea turtles: potential for field applications","volume":"376","author":"Sakamoto","year":"2021","journal-title":"Phil. Trans. R. Soc. B"},{"key":"B19","doi-asserted-by":"publisher","first-page":"1040","DOI":"10.3389\/fpsyg.2014.01040","article-title":"A healthy heart is not a metronome: an integrative review of the heart\u2019s anatomy and heart rate variability","volume":"5","author":"Shaffer","year":"2014","journal-title":"Front. Psychol."},{"key":"B20","doi-asserted-by":"publisher","first-page":"289","DOI":"10.3354\/ab00239","article-title":"Data-processing artefacts in three-dimensional dive path reconstruction from geomagnetic and acceleration data","volume":"8","author":"Shiomi","year":"2010","journal-title":"Aquat. Biol."},{"key":"B21","doi-asserted-by":"publisher","first-page":"293","DOI":"10.1016\/j.physbeh.2007.01.007","article-title":"Heart rate variability as a measure of autonomic regulation of cardiac activity for assessing stress and welfare in farm animals - a review","volume":"92","author":"von Borell","year":"2007","journal-title":"Physiol. Behav."},{"key":"B22","doi-asserted-by":"publisher","first-page":"475","DOI":"10.1242\/jeb.205.4.475","article-title":"Heart rate and energy expenditure of incubating wandering albatrosses: basal levels, natural variation, and the effects of human disturbance","volume":"205","author":"Weimerskirch","year":"2002","journal-title":"J. Exp. Biol."},{"key":"B23","doi-asserted-by":"publisher","first-page":"87","DOI":"10.1242\/jeb.78.1.87","article-title":"The heartbeat of Octopus vulgaris","volume":"78","author":"Wells","year":"1979","journal-title":"J. Exp. Biol."},{"key":"B24","doi-asserted-by":"publisher","first-page":"jeb200824","DOI":"10.1242\/jeb.200824","article-title":"Activity, not submergence, explains diving heart rates of captive loggerhead sea turtles","volume":"222","author":"Williams","year":"2019","journal-title":"J. Exp. Biol."},{"key":"B25","doi-asserted-by":"publisher","first-page":"1081","DOI":"10.1111\/j.1365-2656.2006.01127.x","article-title":"Moving towards acceleration for estimates of activity-specific metabolic rate in free-living animals: the case of the cormorant","volume":"75","author":"Wilson","year":"2006","journal-title":"J. Anim. Ecol."},{"key":"B26","doi-asserted-by":"publisher","first-page":"85","DOI":"10.3354\/meps10592","article-title":"Heart rates of emperor penguins diving at sea: implications for oxygen Store management","volume":"496","author":"Wright","year":"2014","journal-title":"Mar. Ecol. Prog. Ser."}],"container-title":["Frontiers in Physiology"],"original-title":[],"link":[{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2025.1540252\/full","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,7,2]],"date-time":"2025-07-02T05:52:59Z","timestamp":1751435579000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.frontiersin.org\/articles\/10.3389\/fphys.2025.1540252\/full"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,2]]},"references-count":26,"alternative-id":["10.3389\/fphys.2025.1540252"],"URL":"https:\/\/doi.org\/10.3389\/fphys.2025.1540252","relation":{},"ISSN":["1664-042X"],"issn-type":[{"value":"1664-042X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,7,2]]},"article-number":"1540252"}}