Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands

Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands John DeBuysser, Kort Alexander, Heidi Hertler This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7301952/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The present study assesses the mortality or recovery of Acropora cervicornis and Acropora palmata coral fragments on in-situ ocean nurseries during the fourth global coral bleaching event, 2023–2024. Once primary reef-building corals of the Caribbean and tropical western Atlantic, A. cervicornis and A. palmata are now critically endangered species. Population management in the region has been attempted with in-situ and land-based nurseries using the coral gardening restoration concept. However, ocean nurseries are not immune to environmental stressors, and the South Caicos, Turks and Caicos Islands, nursery sites experienced 81.1% mortality during the unprecedented marine heatwave. A. cervicornis had a higher mortality rate (94.2%) than A. palmata (74.7%), and the deepest nursery site at 12.1 m depth had the lowest mortality rate at 54.8%. Further, mortality rates did not differ significantly by nursery structure type. Findings suggest that deeper nurseries are more favorable for coral recovery and survival during heating events, providing restoration practitioners with a method of nursery protection as climate stress continues to intensify for coral reefs. Coral restoration ocean warming Caribbean reefs nursery design Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The fossil record of two essential reef-building corals of the Caribbean and tropical western Atlantic, Acropora palmata , the elkhorn coral, and Acropora cervicornis , the staghorn coral, extends back 6.6 Ma and 3.6–2.6 Ma, respectively (Budd & Johnson, 1999 ; McNeill et al., 1997 ). These corals survived the faunal turnover of the Lower Pleistocene and began to dominate the coral community during the climatic instability and glacial periods of the Holocene (McNeill et al., 1997 ; Prada et al., 2016 ), taking advantage of their success with asexual fragmentation in the surge of the reef crest zone. A product of evolutionary history, Caribbean reefs exhibit low extant coral diversity and recruitment rates, leading to reduced recovery following disturbance events compared to Pacific reefs (Roff, 2021 ). Caribbean Acropora are now critically endangered throughout their range due to anthropogenic impacts including global climate change, disease, habitat destruction, and overfishing (Cramer et al., 2021 ). One of the most prevalent stressors of Caribbean Acropora in 2023 was overheating. Rising sea surface temperatures cause severe bleaching events, and 2023 had the hottest daily average sea surface temperatures (Goreau & Hayes, 2024 ). NOAA confirms 2023 as the start of the fourth global coral bleaching event ( NOAA Confirms 4th Global Coral Bleaching Event | National Oceanic and Atmospheric Administration , 2024). Degree heating weeks are a metric used by NOAA’s Coral Reef Watch to estimate heat stress, with four weeks of 1°C heating equating to a high likelihood of bleaching and eight weeks of 1°C heating equating to severe bleaching and mortality. In 2023, the tropical western Atlantic had 22 degree heating weeks, tripling the previous highest record and prompting the addition of three higher levels of bleaching alerts (Covey 2024 )(Fig. 1 ). Alert Level 5 corresponds to degree heating weeks of 20 or more and risk of near complete mortality of the coral assemblage (NOAA Coral Reef Watch, updated daily). The additional alert levels are still being updated across the NOAA products and not currently available on the DHW product for the Turks and Caicos Islands, but the intense thermal stress can be seen building from June through October in 2023 (Fig. 2). Bleaching is a phenomenon in which corals stressed by temperature or other environmental factors expel their Symbiodinium symbionts, resulting in clear tissue over a white skeleton (Ban et al., 2014 ; Donovan et al., 2020 ; Erftemeijer et al., 2012 ; Negri & Hoogenboom, 2011 ). Bleaching quickly leads to mortality unless temperatures drop and corals are able to reacquire zooxanthellae (Jones, 2008 ). Caribbean reefs experienced widespread bleaching in 2005, 2014–2017 (Eakin et al., 2010 ; Fisch et al., 2019 ), and most recently in 2023 (NOAA 2024). Climate model predictions show an increase in frequency and severity of bleaching events over time, as evidenced with two global bleaching events in the past 10 years (NOAA 2024). Although some corals in the region have shown resilience to bleaching events (Knipp et al., 2020 ), much of the Caribbean is projected to experience annual severe bleaching by 2040 (van Hooidonk et al., 2015 ). The increased frequency of bleaching events will likely limit the full recovery of damaged coral assemblages and lead to the diminishing of reef communities (Hughes et al., 2018 ; McClanahan, 2014 ). Stakeholders and resource managers have noticed declining coral cover and began developing reef restoration methods to rebuild populations with coral gardening techniques (Johnson et al., 2011 ; Maneval et al., 2021 ; Young et al., 2012 ). The methods of this style of restoration typically include coral fragmentation and growth in an in-situ nursery, culminating in the outplanting of cultured colonies on reef substrate. Nursery construction varies widely based on locally available construction materials, incorporating materials such as cement blocks, rebar, PVC pipe, rope, and fishing line. The nursery structure type is chosen to meet prevailing ocean conditions and the goals of the restoration project. However, in-situ nurseries are likely to face mounting challenges as sea surface temperatures continue to increase. The South Caicos Coral Reef Consortium began in January 2023 with the development of four in-situ nurseries and was met in August 2023 with an El Niño period and severe Caribbean mass bleaching event. Our study aims to assess the survival and recovery of coral fragments in the four in-situ nurseries in South Caicos, Turks and Caicos Islands during and following this bleaching period. Methods Study Site Description Four coral nursery sites were installed in the Admiral Cockburn Land and Sea National Park (ACLSNP), Turks and Caicos Islands, between April 5th, 2023, and May 6th, 2023 (Fig. 3 , Table 1 ). A research permit was secured from the Department of Environment and Coastal Resources (DECR) for this project from March 1st, 2023 – February 28th, 2024 (SRP NO: 16–04–01–04). The four nursery sites varied in depth from 5.8 m to 12.4 m and are generally grouped by depth, with Dove Cay and Eagle Ray as shallow sites at less than 10 m depth, and Chain and Plane as deep sites at greater than 10 m depth (Table 1 ). Each site has a unique location in respect to proximity to adjacent cays, channels, and the main reef wall (Fig. 3 ), which affects prevailing local current patterns. At each site, five different construction designs were used as part of the pilot study to determine designs best suited to local conditions (Fig. 4 ). Data Collection Procedure Each nursery site was visited three times during the study. During each visit, structures were cleaned with scrub pads and brushes to remove algae from lines, attachments, and coral identification tags. Tagged A. cervicornis and A. palmata were photographed using a Sealife DC2000 (20mp, 1080p resolution, f = 11.6mm), beginning with a total of 299 coral fragments across the four nurseries at visit T0 and concluding with 264 fragments at visit T2 (Table 2 ). Photographs were loaded into ImageJ (version 2.14.0/1.54f) and the visual health of each coral fragment was assessed. A coral was considered “healthy” if it showed no signs of bleaching or disease, “ partially bleached” if there was tissue lightening but some healthy sections remained, “ bleached” if the entire coral tissue area was white, and “ dead” if living tissue was absent and the skeleton was overgrown by algae. Data analysis and statistics Data were analyzed using R (version 4.3.2) and the tidyverse package (version 1.3.2). Coral fragments were categorized by health status at T1 and T2. Initial and overall mortality rates, proportion bleached or dead at T1, and recovery rates were calculated for the entire project and by nursery site, coral species, and nursery structure type. Initial mortality rate was calculated by dividing the number of dead fragments by the total number of fragments at T1. Overall mortality rate was calculated by dividing the number of dead fragments by the total number of fragments at T2. The proportion bleached or dead at T1, used as a rough proxy for bleaching intensity since many bleached corals had already died by T1, was calculated by summing dead, bleached, and partially bleached fragments and dividing by the total number of fragments. Recovery rate was calculated by dividing the number of fragments that were bleached or partially bleached at T1 but healthy at T2 by the total number of fragments. Lost fragments were not included in rate calculations, as fragment loss from the nursery structures was assumed to be mostly random and not related to bleaching. Fisher’s exact tests (due to small sample sizes) were run using contingency tables to determine association between each rate and site, species, and structure type and for pairwise comparisons. A binary logistic regression model was created to help predict fragment survival and inform future restoration efforts. Fragments were categorized as either live (including healthy, partially bleached, and bleached fragments) or dead. Fragment survival was the dependent variable, and site, species, and structure type were independent variables. Table 1 Names, coordinates, and depths of the four coral nursery sites. Corals were first added to the structures on the “Population Date (T0)”. Health condition and growth were assessed at “First Measurement (T1)” and “Second Measurement (T2)” Nursery Site Coordinates Depth (m) Population Date (T0) First Measurement (T1) Second Measurement (T2) Dove Cay 21.48400 N, 71.52855 W 5.8 m 26-Apr-2023 6-Nov-2023 16-Feb-2024 Eagle Ray 21.48222 N, 71.53367 W 8.2 m 19-Apr-2023 9-Nov-2023 21-Feb-2024 Plane 21.48048 N, 71.53760 W 11.2 m 03-Aug-2023 20-Nov-2023 8-Mar-2024 Chain 21.48168 N, 71.52855 W 12.4 m 04-Aug-2023 13-Nov-2023 6-Mar-2024 Table 2 Coral fragment count at each data collection period. Count includes both living and dead fragments attached to nursery structures. Fragment count decreases over time due to attachment failure during storms or potential faunal interactions with structures. T0 data collection occurred during June, July, and August, 2023; T1 in November of 2023, and T2 in February and March, 2024. Sites were surveyed at different months according to weather and resource availability Site Species T0 Jun-Aug 2023 T1 Nov 2023 T2 Feb-Mar 2024 Chain Acropora cervicornis 25 21 18 Acropora palmata 50 49 44 Dove Cay Acropora cervicornis 25 25 25 Acropora palmata 49 48 46 Eagle Ray Acropora cervicornis 25 24 21 Acropora palmata 50 50 46 Plane Acropora cervicornis 25 22 22 Acropora palmata 50 46 42 Total Acropora cervicornis 100 92 86 Acropora palmata 199 193 178 299 285 264 Results and Discussion The present study assessed fragment survival of two endangered Caribbean reef-building coral species, A. cervicornis and A. palmata , in an in-situ nursery setting during and following the 2023–2024 global coral bleaching event. After the bleaching event, nearly half of the coral fragments that remained on the nursery structures had died, and over 90% were either dead or at least partially bleached (Table 3 , Fig. 5 ). By the end of the study period in spring 2024, 81.1% of the remaining fragments had died. However, 31% of fragments that had bleached were able to recover by the second monitoring period, showing promising signs of resilience. A significant association between site and overall mortality was observed (Fisher’s exact test, p < 0.001 ). The Chain, the deepest nursery, was the most successful site with an overall mortality rate of 54.8%, significantly lower than the mortality at all other sites (Fisher’s exact tests, p < 0.001 vs all three other sites; Table 3 , Fig. 5 ). Light attenuation with depth could be a factor in the survival of the fragments there, although at a similar depth of 11.2 m the Plane had the highest overall mortality of any site at 93.8%. Recovery rate and site also showed a significant association (Fisher’s exact text, p < 0.001 ). Interestingly, despite having similar proportions of bleached or dead fragments at T1 to the other sites, bleached fragments at the Chain recovered at a much higher rate than at the other sites, suggesting more favorable conditions for recovery at that site. The Plane site is more sheltered and farther away from the reef wall than the Chain, which could mean reduced circulation and greater heat stress despite the depth, though further study is necessary. In theory, the shallower nurseries at Dove Cay and Eagle Ray (Table 1 ) would have faced similar thermal stress but higher light levels than the deeper nurseries, potentially elevating coral stress and decreasing recovery rates. The difference in recovery rates between the Chain and Eagle Ray Alley and between the Chain and Dove Cay was significant (Fisher’s exact tests, p < 0.001 ), while the difference between the Chain and the Plane was just above the threshold of significance (Fisher’s exact test, p = 0.053 ). When comparing species, A. palmata fragments fared better than A. cervicornis , with overall mortality rates of 93.5% and 74.7%, respectively (Table 3 ). A. palmata has evolved in the shallower reef crest zone (McNeill et al., 1997 ), developing both a more robust physical structure and a higher resilience to thermal stress, which is likely why both initial and overall mortality were significantly lower for A. palmata than A. cervicornis (Fisher’s exact tests, p < 0.001 ; Table 3 ). Thermal tolerance has its limit in extreme heating, and both species showed similar proportions of bleached or dead fragments at T1 and recovery rates (Fisher’s exact tests, p = 1 ). While there was no association between nursery structure type and overall mortality (Fisher’s exact test, p = 0.145 ) or recovery rate (Fisher’s exact test, p = 0.253 ), structure type was found to be significantly associated with initial mortality (Fisher’s exact test, p < 0.01 ) and proportion of bleached or dead fragments at T1 (Fisher’s exact test, p = 0.033 ), with the cement block being the least successful (init. mortality rate = 61.0%, prop. bleached or dead at T1 = 100.0%) and the PVC tree being the most successful (init. mortality rate = 31.0%, prop. bleached or dead at T1 = 86.2%) by both metrics (Table 3 ). It is possible the increased circulation effect of the PVC trees swaying over their anchor point during the doldrums of the heating event offered an advantage over the block structures. From personal observation, corals on the blocks had the highest sedimentation of all the structure types. A binary logistic regression model based on fragment site, species, and structure supported the above findings and was able to predict fragment survival with an accuracy of 87.1%. A fragment of A. palmata on the rope line structure at the Chain would have the lowest predicted probability of mortality at 32.1%, much lower than the overall observed mortality rate of 81.1%. Site and species were found to be significantly associated with probability of mortality, while structure type was not significant except for the cement block (Fig. 6 , Table 4 ). These results suggest that future restoration efforts around South Caicos should focus on growing elkhorn coral fragments at deeper sites on structures suspended above the seafloor to ensure the most success, lessons which can be applied to other Acropora restoration projects as well. Table 3 Mortality rates, proportion bleached or dead at T1, and recovery rates for all fragments by site, species, and structure type Initial mortality rate (T0-T1) (%) Proportion bleached or dead at T1 (%) Overall mortality rate (T0-T2) (%) Recovery rate (%) Total 44.6 93.3 81.1 31.0 By Site Chain 35.7 91.1 54.8 63.6 Eagle Ray Alley 41.9 97.3 85.1 22.5 Dove Cay 26.0 84.9 88.7 14.3 Plane 76.5 100.0 93.8 28.6 By Species ACER 78.3 93.5 94.2 28.6 APAL 28.5 93.3 74.7 31.3 By Structure Rope Line 53.8 92.3 73.9 47.4 PVC Line Square 44.8 94.8 77.8 40.7 PVC Tree 31.0 86.2 79.6 25.0 Rope Square 32.8 93.1 80.4 25.0 Cement Block 61.0 100.0 91.5 21.7 Table 4 Binary logistic regression model results. Fragment survival (alive or dead) was the dependent variable, while site, species, and nursery structure type were included as independent variables. Odds ratios show the increase in predicted odds of mortality relative to the reference value of each variable. Characteristic Odds Ratio 95% Confidence Interval p-value Site Chain - - - Eagle Ray Alley 5.85 2.43–15.2 < 0.001 Dove Cay 8.12 3.23–22.5 < 0.001 Plane 15 5.01–56.8 < 0.001 Species APAL - - - ACER 6.45 2.49–20.4 < 0.001 Structure type Rope Line - - - PVC Line Square 1.21 0.41–3.56 0.7 PVC Tree 1.07 0.36–3.23 0.9 Rope Square 1.43 0.49–4.29 0.5 Cement Block 4.73 1.40–18.2 0.016 Conclusion Deeper coral nurseries provided measurable benefit to the survival and recovery of A. cervicornis and A. palmata during the fourth global bleaching event, 2023–2024. The nurseries experienced bleaching and mortality but still succeeded in preserving both Acropora species, whereas wild colonies on several adjacent reefs suffered near complete mortality (DeBuysser, pers. obs.). Further study and restoration strategies will need careful investigation and monitoring as ocean temperatures continue to rise and push coral species past their thermal tolerance. For in-situ nurseries facing heating events, reducing solar irradiation by shading or transporting fragments to deeper sites can reduce one aspect of coral stress, potentially increasing recovery rates (Butcherine et al., 2023 ; Tagliafico et al., 2022 ). Outplanting efforts also will need to take into consideration projections of annual SST maxima when placing new colonies, to give them sufficient time to grow and reproduce before succumbing to stronger heat-mortality events. Encouraging the development of populations at the deeper end of their natural range could also increase resilience during heat waves. Further, increasing sexual reproduction management efforts for Caribbean Acropora could help them overcome their genetic bottleneck and increase the chances of adapting to changing ocean conditions. Assessment of thermal stress risk and prudent application of nursery protocols can be an aid to the success of coral population management in the coming years. Declarations Acknowledgements We thank the South Caicos Coral Reef Consortium (SCCRC) partners- School for Field Studies; Salterra, A Luxury Collection Resort and Spa; Reef Institute; Turks and Caicos Reef Fund; Reef Divers; and Scubapro- for their ongoing support of the project. To Adrianna Yeo, Claudia Buckenmeyer, and Kara Rumage for primary data collection and nursery maintenance during the study. To Miranda Williams for her commitment to nursery management. To all the SFS staff and students that built the SCCRC- Dr. Heidi Hertler, Clarence Stringer, Alex Borreil, Mikayla Carrier, Miranda Williams, Conrad Pfalzgraf, Adelaide Biegun, Courtenay Lampert, Faith O’Toole, Mary DiLalla, Grace Hauer, Elle Mangahas, and many more, thank you. To Mateo Arias for his vision of the coral project, this would still be a dream without his efforts. Author contributions JD and HH conceived and designed the experiment. JD and HH conducted the experiment, KA carried out the data analysis. JD and KA wrote the manuscript. All authors revised and approved the manuscript. Funding Research funds provided by the School for Field Studies and the Salterra Resort and Spa. All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors. Conflict of interest The authors have no competing interests to declare that are relevant to the content of this article. Ethical approval Study was conducted under scientific research permit number 16–04–01–04 granted by the Turks and Caicos Islands (TCI) Department of Environment and Coastal Resources (DECR). References Ban, S. S., Graham, N. A. J., & Connolly, S. R. (2014). Evidence for multiple stressor interactions and effects on coral reefs. Global Change Biology , 20 (3), 681–697. https://doi.org/10.1111/gcb.12453 Budd, A. F., & Johnson, K. G. (1999). Origination Preceding Extinction during Late Cenozoic Turnover of Caribbean Reefs. Paleobiology , 25 (2), 188–200. Butcherine, P., Tagliafico, A., Ellis, S. L., Kelaher, B. P., Hendrickson, C., & Harrison, D. (2023). Intermittent shading can moderate coral bleaching on shallow reefs. Frontiers in Marine Science , 10 , 1162896. https://doi.org/10.3389/fmars.2023.1162896 Covey, Z. (2024, February 17). New alert levels added for NOAA’s Coral Reef Watch . https://mynews13.com/fl/orlando/weather/2024/02/13/new-alert-levels-added-for-noaa-s-coral-reef-watch Cramer, K., Jackson, J., & Donovan, M. K. (2021). Widespread loss of Caribbean acroporid corals was underway before coral bleaching and disease outbreaks | Science Advances . https://www.science.org/doi/full/10.1126/sciadv.aax9395 Donovan, M. K., Adam, T. C., Shantz, A. A., Speare, K. E., Munsterman, K. S., Rice, M. M., Schmitt, R. J., Holbrook, S. J., & Burkepile, D. E. (2020). Nitrogen pollution interacts with heat stress to increase coral bleaching across the seascape. Proceedings of the National Academy of Sciences , 117 (10), 5351–5357. https://doi.org/10.1073/pnas.1915395117 Eakin, C. M., Morgan, J. A., Heron, S. F., Smith, T. B., Liu, G., Alvarez-Filip, L., Baca, B., Bartels, E., Bastidas, C., Bouchon, C., Brandt, M., Bruckner, A. W., Bunkley-Williams, L., Cameron, A., Causey, B. D., Chiappone, M., Christensen, T. R. L., Crabbe, M. J. C., Day, O., … Yusuf, Y. (2010). Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005. PLoS ONE , 5 (11), e13969. https://doi.org/10.1371/journal.pone.0013969 Erftemeijer, P. L. A., Riegl, B., Hoeksema, B. W., & Todd, P. A. (2012). Environmental impacts of dredging and other sediment disturbances on corals: A review. Marine Pollution Bulletin , 64 (9), 1737–1765. https://doi.org/10.1016/j.marpolbul.2012.05.008 Fisch, J., Drury, C., Towle, E. K., Winter, R. N., & Miller, M. W. (2019). Physiological and reproductive repercussions of consecutive summer bleaching events of the threatened Caribbean coral Orbicella faveolata. Coral Reefs , 38 (4), 863–876. https://doi.org/10.1007/s00338-019-01817-5 Goreau, T., & Hayes, R. L. (2024). 2023 record marine heat waves: Coral Bleaching HotSpot maps reveal global sea surface temperature extremes, coral mortality, and ocean circulation change . https://eartharxiv.org/repository/view/6603/ Heron, S. F., Eakin, C. M., & Douvere, F. (2017). Impacts of climate change on World Heritage coral reefs: A first global scientific assessment . UNESCO World Heritage Center. https://repository.library.noaa.gov/view/noaa/16386 Hughes, T. P., Anderson, K. D., Connolly, S. R., Heron, S. F., Kerry, J. T., Lough, J. M., Baird, A. H., Baum, J. K., Berumen, M. L., Bridge, T. C., Claar, D. C., Eakin, C. M., Gilmour, J. P., Graham, N. A. J., Harrison, H., Hobbs, J.-P. A., Hoey, A. S., Hoogenboom, M., Lowe, R. J., … Wilson, S. K. (2018). Spatial and temporal patterns of mass bleaching of corals in the Anthropocene. Science , 359 (6371), 80–83. https://doi.org/10.1126/science.aan8048 Johnson, M., Lustic, C., Bartels, E., Baums, I. B., Gilliam, D., Lirman, D., Miller, M. W., Nedimyer, K., & Schopmeyer, S. (2011). Caribbean Acropora restoration guide: Best practices for propagation and population enhancement. The Nature Conservancy . Jones, R. J. (2008). Coral bleaching, bleaching-induced mortality, and the adaptive significance of the bleaching response. Marine Biology , 154 (1), 65–80. https://doi.org/10.1007/s00227-007-0900-0 Knipp, A. L., Pettijohn, J. C., Jadot, C., & Hertler, H. (2020). Contrasting color loss and restoration in survivors of the 2014–2017 coral bleaching event in the Turks and Caicos Islands. SN Applied Sciences , 2 (3), 331. https://doi.org/10.1007/s42452-020-2132-6 Maneval, P., Jacoby, C. A., Harris, H. E., & Frazer, T. K. (2021). Genotype, Nursery Design, and Depth Influence the Growth of Acropora cervicornis Fragments. Frontiers in Marine Science , 8 . https://www.frontiersin.org/articles/10.3389/fmars.2021.670474 McClanahan, T. R. (2014). Decadal coral community reassembly on an African fringing reef. Coral Reefs , 33 (4), 939–950. https://doi.org/10.1007/s00338-014-1178-6 McNeill, D. F., Budd, A. F., & Borne, P. F. (1997). Earlier (late Pliocene) first appearance of the Caribbean reef-building coral Acropora palmata: Stratigraphic and evolutionary implications. Geology , 25 (10), 891. https://doi.org/10.1130/0091-7613(1997)0252.3.CO;2 Negri, A. P., & Hoogenboom, M. O. (2011). Water Contamination Reduces the Tolerance of Coral Larvae to Thermal Stress. PLOS ONE , 6 (5), e19703. https://doi.org/10.1371/journal.pone.0019703 NOAA confirms 4th global coral bleaching event | National Oceanic and Atmospheric Administration . (2024, April 15). https://www.noaa.gov/news-release/noaa-confirms-4th-global-coral-bleaching-event Prada, C., Hanna, B., Budd, A. F., Woodley, C. M., Schmutz, J., Grimwood, J., Iglesias-Prieto, R., Pandolfi, J. M., Levitan, D., Johnson, K. G., Knowlton, N., Kitano, H., DeGiorgio, M., & Medina, M. (2016). Empty Niches after Extinctions Increase Population Sizes of Modern Corals. Current Biology , 26 (23), 3190–3194. https://doi.org/10.1016/j.cub.2016.09.039 Roff, G. (2021). Evolutionary History Drives Biogeographic Patterns of Coral Reef Resilience. BioScience , 71 (1), 26–39. https://doi.org/10.1093/biosci/biaa145 Tagliafico, A., Baker, P., Kelaher, B., Ellis, S., & Harrison, D. (2022). The Effects of Shade and Light on Corals in the Context of Coral Bleaching and Shading Technologies. Frontiers in Marine Science , 9 , 919382. https://doi.org/10.3389/fmars.2022.919382 van Hooidonk, R., Maynard, J. A., Liu, Y., & Lee, S.-K. (2015). Downscaled projections of Caribbean coral bleaching that can inform conservation planning. Global Change Biology , 21 (9), 3389–3401. https://doi.org/10.1111/gcb.12901 Young, C., Schopmeyer, S., & Lirman, D. (2012). A Review of Reef Restoration and Coral Propagation Using the Threatened Genus Acropora in the Caribbean and Western Atlantic. Bulletin of Marine Science , 88 (4), 1075–1098. https://doi.org/10.5343/bms.2011.1143 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7301952","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":500616299,"identity":"eb8746a9-8eec-4879-96f6-ab0a4bcf13ab","order_by":0,"name":"John DeBuysser","email":"data:image/png;base64,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","orcid":"","institution":"School for Field Studies","correspondingAuthor":true,"prefix":"","firstName":"John","middleName":"","lastName":"DeBuysser","suffix":""},{"id":500616300,"identity":"d46e03e8-31ad-4c74-9f94-51f3f0f0fcfd","order_by":1,"name":"Kort Alexander","email":"","orcid":"","institution":"School for Field Studies","correspondingAuthor":false,"prefix":"","firstName":"Kort","middleName":"","lastName":"Alexander","suffix":""},{"id":500616301,"identity":"17348e50-f54b-4eb0-b2bf-818e325329b0","order_by":2,"name":"Heidi Hertler","email":"","orcid":"","institution":"School for Field Studies","correspondingAuthor":false,"prefix":"","firstName":"Heidi","middleName":"","lastName":"Hertler","suffix":""}],"badges":[],"createdAt":"2025-08-05 14:53:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7301952/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7301952/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":89268640,"identity":"7eb8c38f-464b-4dab-8b2c-9fec1b06dd1c","added_by":"auto","created_at":"2025-08-18 08:26:35","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":789383,"visible":true,"origin":"","legend":"\u003cp\u003eNOAA Coral Reef Watch's global 5km-resolution satellite Coral Bleaching Alert Area Maximum map, for January 1, 2023 to April 10, 2024. This figure shows the regions, around the globe, that experienced high levels of marine heat stress (Bleaching Alert Levels 2-5) that can cause reef-wide coral bleaching and mortality. Image credit: NOAA\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/961e782641792e72d9e4d49d.png"},{"id":89268639,"identity":"e0eedb17-1ae0-4499-bd2d-fbf08152d1fb","added_by":"auto","created_at":"2025-08-18 08:26:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":129750,"visible":true,"origin":"","legend":"\u003cp\u003eNOAA Coral Reef Watch\u003cstrong\u003e \u003c/strong\u003eTurks and Caicos time series graph. The sea surface temperature (SST) value is shown in the center of the graph and read using the vertical axis on the left. The degree heating weeks (DHW) is shown in the bottom portion of the graphs and read using the vertical axis on the right. In both the two-year and multi-year graphs, the coral bleaching heat stress level (or Bleaching Alert Level) is color-coded and drawn along the bottom horizontal axis. Bleaching heat stress is categorized into five bleaching risk levels based on the summary of the Coral Bleaching HotSpot and Degree Heating Week values experienced. Image credit: NOAA\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/8854027d95a6e11229831cbe.png"},{"id":89268958,"identity":"af715608-06b7-4f17-91e6-d90e2239212d","added_by":"auto","created_at":"2025-08-18 08:34:35","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":114238,"visible":true,"origin":"","legend":"\u003cp\u003eM ap of four \u003cem\u003ein-situ \u003c/em\u003ecoral nursery sites located in South Caicos, Turks and Caicos Islands. GPS coordinates and water depths are listed in Table 1. Map created in Google Earth by John DeBuysser\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/13b131a827832d6b43d3360d.png"},{"id":89270191,"identity":"24286152-1564-4e84-af03-76724db3189f","added_by":"auto","created_at":"2025-08-18 08:42:35","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":270476,"visible":true,"origin":"","legend":"\u003cp\u003eImages of the five nursery structure types. \u003cstrong\u003ea \u003c/strong\u003eRope and Line, comprised of two vertical, sub-surface ropes with fishing line rows strung horizontally between the ropes. \u003cstrong\u003eB\u003c/strong\u003e PVC Coral Tree, typical of design popularized by Coral Restoration Foundation. \u003cstrong\u003ec \u003c/strong\u003ePVC Rope Square, a 2 m x 2 m PVC square with horizontal rows of three-strand rope strung between the vertical sides. \u003cstrong\u003ed \u003c/strong\u003ePVC Line Square, similar in size and design to \u003cstrong\u003ec \u003c/strong\u003ebut with fishing line on the horizontal rows. \u003cstrong\u003ee\u003c/strong\u003e Cement Block, two cinder blocks attached together with eight PVC risers per block onto which the coral plugs are attached. Photographs taken by Heidi Hertler\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/137b1a72dfdab401dd5bb2ef.png"},{"id":89268647,"identity":"5d95bf73-21ad-4a58-a53e-3cb60f8952e5","added_by":"auto","created_at":"2025-08-18 08:26:35","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":303003,"visible":true,"origin":"","legend":"\u003cp\u003eHealth status of coral fragments by site, species, and structure. \u003cstrong\u003eA.\u003c/strong\u003e Health status of fragments during the first monitoring period in fall 2023 (T1). \u003cstrong\u003eB. \u003c/strong\u003eHealth status of fragments during the second monitoring period in spring 2024 (T2).\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/e8f263abb8a1824b3a6fb8c8.png"},{"id":89268651,"identity":"deeb72aa-2f35-4680-b735-3c01aca0c161","added_by":"auto","created_at":"2025-08-18 08:26:35","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":256233,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of site, species, and structure type on coral fragment survival. Probability of mortality predicted by combined binary logistic regression model is plotted on the y-axis, while predictor variables are plotted on the x-axis.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/f350b806caccabdf5c4c8371.png"},{"id":95442109,"identity":"96002d5b-b98e-45e4-ad29-588c24cfbfeb","added_by":"auto","created_at":"2025-11-08 14:23:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2593303,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7301952/v1/af30ed0a-4206-4bcc-9673-6c6df5532036.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe fossil record of two essential reef-building corals of the Caribbean and tropical western Atlantic, \u003cem\u003eAcropora palmata\u003c/em\u003e, the elkhorn coral, and \u003cem\u003eAcropora cervicornis\u003c/em\u003e, the staghorn coral, extends back 6.6 Ma and 3.6\u0026ndash;2.6 Ma, respectively (Budd \u0026amp; Johnson, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; McNeill et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). These corals survived the faunal turnover of the Lower Pleistocene and began to dominate the coral community during the climatic instability and glacial periods of the Holocene (McNeill et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Prada et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), taking advantage of their success with asexual fragmentation in the surge of the reef crest zone. A product of evolutionary history, Caribbean reefs exhibit low extant coral diversity and recruitment rates, leading to reduced recovery following disturbance events compared to Pacific reefs (Roff, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Caribbean \u003cem\u003eAcropora\u003c/em\u003e are now critically endangered throughout their range due to anthropogenic impacts including global climate change, disease, habitat destruction, and overfishing (Cramer et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eOne of the most prevalent stressors of Caribbean \u003cem\u003eAcropora\u003c/em\u003e in 2023 was overheating. Rising sea surface temperatures cause severe bleaching events, and 2023 had the hottest daily average sea surface temperatures (Goreau \u0026amp; Hayes, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). NOAA confirms 2023 as the start of the fourth global coral bleaching event (\u003cem\u003eNOAA Confirms 4th Global Coral Bleaching Event | National Oceanic and Atmospheric Administration\u003c/em\u003e, 2024). Degree heating weeks are a metric used by NOAA\u0026rsquo;s Coral Reef Watch to estimate heat stress, with four weeks of 1\u0026deg;C heating equating to a high likelihood of bleaching and eight weeks of 1\u0026deg;C heating equating to severe bleaching and mortality. In 2023, the tropical western Atlantic had 22 degree heating weeks, tripling the previous highest record and prompting the addition of three higher levels of bleaching alerts (Covey \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2024\u003c/span\u003e)(Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Alert Level 5 corresponds to degree heating weeks of 20 or more and risk of near complete mortality of the coral assemblage (NOAA Coral Reef Watch, updated daily). The additional alert levels are still being updated across the NOAA products and not currently available on the DHW product for the Turks and Caicos Islands, but the intense thermal stress can be seen building from June through October in 2023 (Fig.\u0026nbsp;2).\u003c/p\u003e\u003cp\u003eBleaching is a phenomenon in which corals stressed by temperature or other environmental factors expel their \u003cem\u003eSymbiodinium\u003c/em\u003e symbionts, resulting in clear tissue over a white skeleton (Ban et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Donovan et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Erftemeijer et al., \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Negri \u0026amp; Hoogenboom, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Bleaching quickly leads to mortality unless temperatures drop and corals are able to reacquire zooxanthellae (Jones, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Caribbean reefs experienced widespread bleaching in 2005, 2014\u0026ndash;2017 (Eakin et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Fisch et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), and most recently in 2023 (NOAA\u003c/p\u003e\u003cp\u003e2024). Climate model predictions show an increase in frequency and severity of bleaching events over time, as evidenced with two global bleaching events in the past 10 years (NOAA 2024). Although some corals in the region have shown resilience to bleaching events (Knipp et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), much of the Caribbean is projected to experience annual severe bleaching by 2040 (van Hooidonk et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). The increased frequency of bleaching events will likely limit the full recovery of damaged coral assemblages and lead to the diminishing of reef communities (Hughes et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; McClanahan, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2014\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eStakeholders and resource managers have noticed declining coral cover and began developing reef restoration methods to rebuild populations with coral gardening techniques (Johnson et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Maneval et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Young et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). The methods of this style of restoration typically include coral fragmentation and growth in an \u003cem\u003ein-situ\u003c/em\u003e nursery, culminating in the outplanting of cultured colonies on reef substrate. Nursery construction varies widely based on locally available construction materials, incorporating materials such as cement blocks, rebar, PVC pipe, rope, and fishing line. The nursery structure type is chosen to meet prevailing ocean conditions and the goals of the restoration project. However, \u003cem\u003ein-situ\u003c/em\u003e nurseries are likely to face mounting challenges as sea surface temperatures continue to increase. The South Caicos Coral Reef Consortium began in January 2023 with the development of four \u003cem\u003ein-situ\u003c/em\u003e nurseries and was met in August 2023 with an El Ni\u0026ntilde;o period and severe Caribbean mass bleaching event. Our study aims to assess the survival and recovery of coral fragments in the four \u003cem\u003ein-situ\u003c/em\u003e nurseries in South Caicos, Turks and Caicos Islands during and following this bleaching period.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStudy Site Description\u003c/h2\u003e\u003cp\u003eFour coral nursery sites were installed in the Admiral Cockburn Land and Sea National Park (ACLSNP), Turks and Caicos Islands, between April 5th, 2023, and May 6th, 2023 (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). A research permit was secured from the Department of Environment and Coastal Resources (DECR) for this project from March 1st, 2023 \u0026ndash; February 28th, 2024 (SRP NO: 16\u0026ndash;04\u0026ndash;01\u0026ndash;04). The four nursery sites varied in depth from 5.8 m to 12.4 m and are generally grouped by depth, with Dove Cay and Eagle Ray as shallow sites at less than 10 m depth, and Chain and Plane as deep sites at greater than 10 m depth (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Each site has a unique location in respect to proximity to adjacent cays, channels, and the main reef wall (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e), which affects prevailing local current patterns. At each site, five different construction designs were used as part of the pilot study to determine designs best suited to local conditions (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eData Collection Procedure\u003c/h3\u003e\n\u003cp\u003eEach nursery site was visited three times during the study. During each visit, structures were cleaned with scrub pads and brushes to remove algae from lines, attachments, and coral identification tags. Tagged \u003cem\u003eA. cervicornis\u003c/em\u003e and \u003cem\u003eA. palmata\u003c/em\u003e were photographed using a Sealife DC2000 (20mp, 1080p resolution, f\u0026thinsp;=\u0026thinsp;11.6mm), beginning with a total of 299 coral fragments across the four nurseries at visit T0 and concluding with 264 fragments at visit T2 (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Photographs were loaded into ImageJ (version 2.14.0/1.54f) and the visual health of each coral fragment was assessed. A coral was considered \u003cem\u003e\u0026ldquo;healthy\u0026rdquo;\u003c/em\u003e if it showed no signs of bleaching or disease, \u0026ldquo;\u003cem\u003epartially bleached\u0026rdquo;\u003c/em\u003e if there was tissue lightening but some healthy sections remained, \u0026ldquo;\u003cem\u003ebleached\u0026rdquo;\u003c/em\u003e if the entire coral tissue area was white, and \u0026ldquo;\u003cem\u003edead\u0026rdquo;\u003c/em\u003e if living tissue was absent and the skeleton was overgrown by algae.\u003c/p\u003e\n\u003ch3\u003eData analysis and statistics\u003c/h3\u003e\n\u003cp\u003eData were analyzed using R (version 4.3.2) and the tidyverse package (version 1.3.2). Coral fragments were categorized by health status at T1 and T2. Initial and overall mortality rates, proportion bleached or dead at T1, and recovery rates were calculated for the entire project and by nursery site, coral species, and nursery structure type. Initial mortality rate was calculated by dividing the number of dead fragments by the total number of fragments at T1. Overall mortality rate was calculated by dividing the number of dead fragments by the total number of fragments at T2. The proportion bleached or dead at T1, used as a rough proxy for bleaching intensity since many bleached corals had already died by T1, was calculated by summing dead, bleached, and partially bleached fragments and dividing by the total number of fragments. Recovery rate was calculated by dividing the number of fragments that were bleached or partially bleached at T1 but healthy at T2 by the total number of fragments. Lost fragments were not included in rate calculations, as fragment loss from the nursery structures was assumed to be mostly random and not related to bleaching. Fisher\u0026rsquo;s exact tests (due to small sample sizes) were run using contingency tables to determine association between each rate and site, species, and structure type and for pairwise comparisons.\u003c/p\u003e\u003cp\u003eA binary logistic regression model was created to help predict fragment survival and inform future restoration efforts. Fragments were categorized as either live (including healthy, partially bleached, and bleached fragments) or dead. Fragment survival was the dependent variable, and site, species, and structure type were independent variables.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eNames, coordinates, and depths of the four coral nursery sites. Corals were first added to the structures on the \u0026ldquo;Population Date (T0)\u0026rdquo;. Health condition and growth were assessed at \u0026ldquo;First Measurement (T1)\u0026rdquo; and \u0026ldquo;Second Measurement (T2)\u0026rdquo;\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNursery Site\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoordinates\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eDepth (m)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003ePopulation Date (T0)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eFirst Measurement (T1)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eSecond Measurement (T2)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDove Cay\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.48400 N, 71.52855 W\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.8 m\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26-Apr-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6-Nov-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e16-Feb-2024\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEagle Ray\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.48222 N, 71.53367 W\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.2 m\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e19-Apr-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e9-Nov-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e21-Feb-2024\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlane\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.48048 N, 71.53760 W\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e11.2 m\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e03-Aug-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20-Nov-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e8-Mar-2024\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21.48168 N, 71.52855 W\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e12.4 m\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e04-Aug-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e13-Nov-2023\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6-Mar-2024\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eCoral fragment count at each data collection period. Count includes both living and dead fragments attached to nursery structures. Fragment count decreases over time due to attachment failure during storms or potential faunal interactions with structures. T0 data collection occurred during June, July, and August, 2023; T1 in November of 2023, and T2 in February and March, 2024. Sites were surveyed at different months according to weather and resource availability\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSite\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpecies\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eT0\u003c/p\u003e\u003cp\u003eJun-Aug 2023\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eT1\u003c/p\u003e\u003cp\u003eNov\u003c/p\u003e\u003cp\u003e2023\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eT2\u003c/p\u003e\u003cp\u003eFeb-Mar 2024\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eChain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora cervicornis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora palmata\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eDove Cay\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora cervicornis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora palmata\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eEagle Ray\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora cervicornis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora palmata\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ePlane\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora cervicornis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora palmata\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e46\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora cervicornis\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eAcropora palmata\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e199\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e193\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e178\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e299\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e285\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e264\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eThe present study assessed fragment survival of two endangered Caribbean reef-building coral species, \u003cem\u003eA. cervicornis\u003c/em\u003e and \u003cem\u003eA. palmata\u003c/em\u003e, in an \u003cem\u003ein-situ\u003c/em\u003e nursery setting during and following the 2023\u0026ndash;2024 global coral bleaching event. After the bleaching event, nearly half of the coral fragments that remained on the nursery structures had died, and over 90% were either dead or at least partially bleached (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e). By the end of the study period in spring 2024, 81.1% of the remaining fragments had died. However, 31% of fragments that had bleached were able to recover by the second monitoring period, showing promising signs of resilience.\u003c/p\u003e\u003cp\u003eA significant association between site and overall mortality was observed (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/em\u003e). The Chain, the deepest nursery, was the most successful site with an overall mortality rate of 54.8%, significantly lower than the mortality at all other sites (Fisher\u0026rsquo;s exact tests, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/em\u003e vs all three other sites; Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Light attenuation with depth could be a factor in the survival of the fragments there, although at a similar depth of 11.2 m the Plane had the highest overall mortality of any site at 93.8%.\u003c/p\u003e\u003cp\u003eRecovery rate and site also showed a significant association (Fisher\u0026rsquo;s exact text, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/em\u003e). Interestingly, despite having similar proportions of bleached or dead fragments at T1 to the other sites, bleached fragments at the Chain recovered at a much higher rate than at the other sites, suggesting more favorable conditions for recovery at that site. The Plane site is more sheltered and farther away from the reef wall than the Chain, which could mean reduced circulation and greater heat stress despite the depth, though further study is necessary. In theory, the shallower nurseries at Dove Cay and Eagle Ray (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) would have faced similar thermal stress but higher light levels than the deeper nurseries, potentially elevating coral stress and decreasing recovery rates. The difference in recovery rates between the Chain and Eagle Ray Alley and between the Chain and Dove Cay was significant (Fisher\u0026rsquo;s exact tests, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/em\u003e), while the difference between the Chain and the Plane was just above the threshold of significance (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;=\u0026thinsp;0.053\u003c/em\u003e).\u003c/p\u003e\u003cp\u003eWhen comparing species, \u003cem\u003eA. palmata\u003c/em\u003e fragments fared better than \u003cem\u003eA. cervicornis\u003c/em\u003e, with overall mortality rates of 93.5% and 74.7%, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). \u003cem\u003eA. palmata\u003c/em\u003e has evolved in the shallower reef crest zone (McNeill et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e1997\u003c/span\u003e), developing both a more robust physical structure and a higher resilience to thermal stress, which is likely why both initial and overall mortality were significantly lower for \u003cem\u003eA. palmata\u003c/em\u003e than \u003cem\u003eA. cervicornis\u003c/em\u003e (Fisher\u0026rsquo;s exact tests, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.001\u003c/em\u003e; Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Thermal tolerance has its limit in extreme heating, and both species showed similar proportions of bleached or dead fragments at T1 and recovery rates (Fisher\u0026rsquo;s exact tests, \u003cem\u003ep\u0026thinsp;=\u0026thinsp;1\u003c/em\u003e).\u003c/p\u003e\u003cp\u003eWhile there was no association between nursery structure type and overall mortality (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;=\u0026thinsp;0.145\u003c/em\u003e) or recovery rate (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;=\u0026thinsp;0.253\u003c/em\u003e), structure type was found to be significantly associated with initial mortality (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;\u0026lt;\u0026thinsp;0.01\u003c/em\u003e) and proportion of bleached or dead fragments at T1 (Fisher\u0026rsquo;s exact test, \u003cem\u003ep\u0026thinsp;=\u0026thinsp;0.033\u003c/em\u003e), with the cement block being the least successful (init. mortality rate\u0026thinsp;=\u0026thinsp;61.0%, prop. bleached or dead at T1\u0026thinsp;=\u0026thinsp;100.0%) and the PVC tree being the most successful (init. mortality rate\u0026thinsp;=\u0026thinsp;31.0%, prop. bleached or dead at T1\u0026thinsp;=\u0026thinsp;86.2%) by both metrics (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). It is possible the increased circulation effect of the PVC trees swaying over their anchor point during the doldrums of the heating event offered an advantage over the block structures. From personal observation, corals on the blocks had the highest sedimentation of all the structure types.\u003c/p\u003e\u003cp\u003eA binary logistic regression model based on fragment site, species, and structure supported the above findings and was able to predict fragment survival with an accuracy of 87.1%. A fragment of \u003cem\u003eA. palmata\u003c/em\u003e on the rope line structure at the Chain would have the lowest predicted probability of mortality at 32.1%, much lower than the overall observed mortality rate of 81.1%. Site and species were found to be significantly associated with probability of mortality, while structure type was not significant except for the cement block (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e, Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These results suggest that future restoration efforts around South Caicos should focus on growing elkhorn coral fragments at deeper sites on structures suspended above the seafloor to ensure the most success, lessons which can be applied to other \u003cem\u003eAcropora\u003c/em\u003e restoration projects as well.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMortality rates, proportion bleached or dead at T1, and recovery rates for all fragments by site, species, and structure type\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eInitial mortality rate (T0-T1) (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eProportion bleached or dead at T1 (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eOverall mortality rate (T0-T2) (%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eRecovery rate (%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eTotal\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e44.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e81.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e31.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003eBy Site\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e35.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e91.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e54.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e63.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEagle Ray Alley\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e41.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e97.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e85.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e22.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDove Cay\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e26.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e84.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e88.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e14.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePlane\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e76.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e100.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e93.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e28.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eBy Species\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eACER\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e78.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e94.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e28.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAPAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e28.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e74.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e31.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eBy Structure\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRope Line\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e53.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e92.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e73.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e47.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePVC Line Square\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e44.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e94.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e77.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e40.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePVC Tree\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e31.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e86.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e79.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e25.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRope Square\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e32.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e93.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e80.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e25.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCement Block\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e61.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e100.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e91.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e21.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eBinary logistic regression model results. Fragment survival (alive or dead) was the dependent variable, while site, species, and nursery structure type were included as independent variables. Odds ratios show the increase in predicted odds of mortality relative to the reference value of each variable.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eCharacteristic\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOdds Ratio\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e95% Confidence Interval\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003eSite\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eEagle Ray Alley\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e5.85\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.43\u0026ndash;15.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDove Cay\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e3.23\u0026ndash;22.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePlane\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.01\u0026ndash;56.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSpecies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAPAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eACER\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.49\u0026ndash;20.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e\u003cp\u003eStructure type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRope Line\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePVC Line Square\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.41\u0026ndash;3.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePVC Tree\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.36\u0026ndash;3.23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRope Square\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.49\u0026ndash;4.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCement Block\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.40\u0026ndash;18.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.016\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eDeeper coral nurseries provided measurable benefit to the survival and recovery of \u003cem\u003eA. cervicornis\u003c/em\u003e and \u003cem\u003eA. palmata\u003c/em\u003e during the fourth global bleaching event, 2023\u0026ndash;2024. The nurseries experienced bleaching and mortality but still succeeded in preserving both \u003cem\u003eAcropora\u003c/em\u003e species, whereas wild colonies on several adjacent reefs suffered near complete mortality (DeBuysser, pers. obs.). Further study and restoration strategies will need careful investigation and monitoring as ocean temperatures continue to rise and push coral species past their thermal tolerance. For \u003cem\u003ein-situ\u003c/em\u003e nurseries facing heating events, reducing solar irradiation by shading or transporting fragments to deeper sites can reduce one aspect of coral stress, potentially increasing recovery rates (Butcherine et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Tagliafico et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Outplanting efforts also will need to take into consideration projections of annual SST maxima when placing new colonies, to give them sufficient time to grow and reproduce before succumbing to stronger heat-mortality events. Encouraging the development of populations at the deeper end of their natural range could also increase resilience during heat waves. Further, increasing sexual reproduction management efforts for Caribbean \u003cem\u003eAcropora\u003c/em\u003e could help them overcome their genetic bottleneck and increase the chances of adapting to changing ocean conditions. Assessment of thermal stress risk and prudent application of nursery protocols can be an aid to the success of coral population management in the coming years.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e We thank the South Caicos Coral Reef Consortium (SCCRC) partners- School for Field Studies; Salterra, A Luxury Collection Resort and Spa; Reef Institute; Turks and Caicos Reef Fund; Reef Divers; and Scubapro- for their ongoing support of the project. To Adrianna Yeo, Claudia Buckenmeyer, and Kara Rumage for primary data collection and nursery maintenance during the study. To Miranda Williams for her commitment to nursery management. To all the SFS staff and students that built the SCCRC- Dr. Heidi Hertler, Clarence Stringer, Alex Borreil, Mikayla Carrier, Miranda Williams, Conrad Pfalzgraf, Adelaide Biegun, Courtenay Lampert, Faith O’Toole, Mary DiLalla, Grace Hauer, Elle Mangahas, and many more, thank you. To Mateo Arias for his vision of the coral project, this would still be a dream without his efforts.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e JD and HH conceived and designed the experiment. JD and HH conducted the experiment, KA carried out the data analysis. JD and KA wrote the manuscript. All authors revised and approved the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e Research funds provided by the School for Field Studies and the Salterra Resort and Spa.\u003c/p\u003e\n\u003cp\u003eAll authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e Study was conducted under scientific research permit number 16–04–01–04 granted by the Turks and Caicos Islands (TCI) Department of Environment and Coastal Resources (DECR).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBan, S. S., Graham, N. A. J., \u0026amp; Connolly, S. R. (2014). Evidence for multiple stressor interactions and effects on coral reefs. \u003cem\u003eGlobal Change Biology\u003c/em\u003e, \u003cem\u003e20\u003c/em\u003e(3), 681\u0026ndash;697. https://doi.org/10.1111/gcb.12453\u003c/li\u003e\n\u003cli\u003eBudd, A. F., \u0026amp; Johnson, K. G. (1999). Origination Preceding Extinction during Late Cenozoic Turnover of Caribbean Reefs. \u003cem\u003ePaleobiology\u003c/em\u003e, \u003cem\u003e25\u003c/em\u003e(2), 188\u0026ndash;200.\u003c/li\u003e\n\u003cli\u003eButcherine, P., Tagliafico, A., Ellis, S. L., Kelaher, B. P., Hendrickson, C., \u0026amp; Harrison, D. (2023). Intermittent shading can moderate coral bleaching on shallow reefs. \u003cem\u003eFrontiers in Marine Science\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e, 1162896. https://doi.org/10.3389/fmars.2023.1162896\u003c/li\u003e\n\u003cli\u003eCovey, Z. (2024, February 17). \u003cem\u003eNew alert levels added for NOAA\u0026rsquo;s Coral Reef Watch\u003c/em\u003e. https://mynews13.com/fl/orlando/weather/2024/02/13/new-alert-levels-added-for-noaa-s-coral-reef-watch\u003c/li\u003e\n\u003cli\u003eCramer, K., Jackson, J., \u0026amp; Donovan, M. K. (2021). \u003cem\u003eWidespread loss of Caribbean acroporid corals was underway before coral bleaching and disease outbreaks | Science Advances\u003c/em\u003e. https://www.science.org/doi/full/10.1126/sciadv.aax9395\u003c/li\u003e\n\u003cli\u003eDonovan, M. K., Adam, T. C., Shantz, A. A., Speare, K. E., Munsterman, K. S., Rice, M. M., Schmitt, R. J., Holbrook, S. J., \u0026amp; Burkepile, D. E. (2020). Nitrogen pollution interacts with heat stress to increase coral bleaching across the seascape. \u003cem\u003eProceedings of the National Academy of Sciences\u003c/em\u003e, \u003cem\u003e117\u003c/em\u003e(10), 5351\u0026ndash;5357. https://doi.org/10.1073/pnas.1915395117\u003c/li\u003e\n\u003cli\u003eEakin, C. M., Morgan, J. A., Heron, S. F., Smith, T. B., Liu, G., Alvarez-Filip, L., Baca, B., Bartels, E., Bastidas, C., Bouchon, C., Brandt, M., Bruckner, A. W., Bunkley-Williams, L., Cameron, A., Causey, B. D., Chiappone, M., Christensen, T. R. L., Crabbe, M. J. C., Day, O., \u0026hellip; Yusuf, Y. (2010). Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005. \u003cem\u003ePLoS ONE\u003c/em\u003e, \u003cem\u003e5\u003c/em\u003e(11), e13969. https://doi.org/10.1371/journal.pone.0013969\u003c/li\u003e\n\u003cli\u003eErftemeijer, P. L. A., Riegl, B., Hoeksema, B. W., \u0026amp; Todd, P. A. (2012). Environmental impacts of dredging and other sediment disturbances on corals: A review. \u003cem\u003eMarine Pollution Bulletin\u003c/em\u003e, \u003cem\u003e64\u003c/em\u003e(9), 1737\u0026ndash;1765. https://doi.org/10.1016/j.marpolbul.2012.05.008\u003c/li\u003e\n\u003cli\u003eFisch, J., Drury, C., Towle, E. K., Winter, R. N., \u0026amp; Miller, M. W. (2019). Physiological and reproductive repercussions of consecutive summer bleaching events of the threatened Caribbean coral Orbicella faveolata. \u003cem\u003eCoral Reefs\u003c/em\u003e, \u003cem\u003e38\u003c/em\u003e(4), 863\u0026ndash;876. https://doi.org/10.1007/s00338-019-01817-5\u003c/li\u003e\n\u003cli\u003eGoreau, T., \u0026amp; Hayes, R. L. (2024). \u003cem\u003e2023 record marine heat waves: Coral Bleaching HotSpot maps reveal global sea surface temperature extremes, coral mortality, and ocean circulation change\u003c/em\u003e. https://eartharxiv.org/repository/view/6603/\u003c/li\u003e\n\u003cli\u003eHeron, S. F., Eakin, C. M., \u0026amp; Douvere, F. (2017). \u003cem\u003eImpacts of climate change on World Heritage coral reefs: A first global scientific assessment\u003c/em\u003e. UNESCO World Heritage Center. https://repository.library.noaa.gov/view/noaa/16386\u003c/li\u003e\n\u003cli\u003eHughes, T. P., Anderson, K. D., Connolly, S. R., Heron, S. F., Kerry, J. T., Lough, J. M., Baird, A. H., Baum, J. K., Berumen, M. L., Bridge, T. C., Claar, D. C., Eakin, C. M., Gilmour, J. P., Graham, N. A. J., Harrison, H., Hobbs, J.-P. A., Hoey, A. S., Hoogenboom, M., Lowe, R. J., \u0026hellip; Wilson, S. K. (2018). Spatial and temporal patterns of mass bleaching of corals in the Anthropocene. \u003cem\u003eScience\u003c/em\u003e, \u003cem\u003e359\u003c/em\u003e(6371), 80\u0026ndash;83. https://doi.org/10.1126/science.aan8048\u003c/li\u003e\n\u003cli\u003eJohnson, M., Lustic, C., Bartels, E., Baums, I. B., Gilliam, D., Lirman, D., Miller, M. W., Nedimyer, K., \u0026amp; Schopmeyer, S. (2011). Caribbean Acropora restoration guide: Best practices for propagation and population enhancement. \u003cem\u003eThe Nature Conservancy\u003c/em\u003e.\u003c/li\u003e\n\u003cli\u003eJones, R. J. (2008). Coral bleaching, bleaching-induced mortality, and the adaptive significance of the bleaching response. \u003cem\u003eMarine Biology\u003c/em\u003e, \u003cem\u003e154\u003c/em\u003e(1), 65\u0026ndash;80. https://doi.org/10.1007/s00227-007-0900-0\u003c/li\u003e\n\u003cli\u003eKnipp, A. L., Pettijohn, J. C., Jadot, C., \u0026amp; Hertler, H. (2020). Contrasting color loss and restoration in survivors of the 2014\u0026ndash;2017 coral bleaching event in the Turks and Caicos Islands. \u003cem\u003eSN Applied Sciences\u003c/em\u003e, \u003cem\u003e2\u003c/em\u003e(3), 331. https://doi.org/10.1007/s42452-020-2132-6\u003c/li\u003e\n\u003cli\u003eManeval, P., Jacoby, C. A., Harris, H. E., \u0026amp; Frazer, T. K. (2021). Genotype, Nursery Design, and Depth Influence the Growth of Acropora cervicornis Fragments. \u003cem\u003eFrontiers in Marine Science\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e. https://www.frontiersin.org/articles/10.3389/fmars.2021.670474\u003c/li\u003e\n\u003cli\u003eMcClanahan, T. R. (2014). Decadal coral community reassembly on an African fringing reef. \u003cem\u003eCoral Reefs\u003c/em\u003e, \u003cem\u003e33\u003c/em\u003e(4), 939\u0026ndash;950. https://doi.org/10.1007/s00338-014-1178-6\u003c/li\u003e\n\u003cli\u003eMcNeill, D. F., Budd, A. F., \u0026amp; Borne, P. F. (1997). Earlier (late Pliocene) first appearance of the Caribbean reef-building coral Acropora palmata: Stratigraphic and evolutionary implications. \u003cem\u003eGeology\u003c/em\u003e, \u003cem\u003e25\u003c/em\u003e(10), 891. https://doi.org/10.1130/0091-7613(1997)025\u0026lt;0891:ELPFAO\u0026gt;2.3.CO;2\u003c/li\u003e\n\u003cli\u003eNegri, A. P., \u0026amp; Hoogenboom, M. O. (2011). Water Contamination Reduces the Tolerance of Coral Larvae to Thermal Stress. \u003cem\u003ePLOS ONE\u003c/em\u003e, \u003cem\u003e6\u003c/em\u003e(5), e19703. https://doi.org/10.1371/journal.pone.0019703\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eNOAA confirms 4th global coral bleaching event | National Oceanic and Atmospheric Administration\u003c/em\u003e. (2024, April 15). https://www.noaa.gov/news-release/noaa-confirms-4th-global-coral-bleaching-event\u003c/li\u003e\n\u003cli\u003ePrada, C., Hanna, B., Budd, A. F., Woodley, C. M., Schmutz, J., Grimwood, J., Iglesias-Prieto, R., Pandolfi, J. M., Levitan, D., Johnson, K. G., Knowlton, N., Kitano, H., DeGiorgio, M., \u0026amp; Medina, M. (2016). Empty Niches after Extinctions Increase Population Sizes of Modern Corals. \u003cem\u003eCurrent Biology\u003c/em\u003e, \u003cem\u003e26\u003c/em\u003e(23), 3190\u0026ndash;3194. https://doi.org/10.1016/j.cub.2016.09.039\u003c/li\u003e\n\u003cli\u003eRoff, G. (2021). Evolutionary History Drives Biogeographic Patterns of Coral Reef Resilience. \u003cem\u003eBioScience\u003c/em\u003e, \u003cem\u003e71\u003c/em\u003e(1), 26\u0026ndash;39. https://doi.org/10.1093/biosci/biaa145\u003c/li\u003e\n\u003cli\u003eTagliafico, A., Baker, P., Kelaher, B., Ellis, S., \u0026amp; Harrison, D. (2022). The Effects of Shade and Light on Corals in the Context of Coral Bleaching and Shading Technologies. \u003cem\u003eFrontiers in Marine Science\u003c/em\u003e, \u003cem\u003e9\u003c/em\u003e, 919382. https://doi.org/10.3389/fmars.2022.919382\u003c/li\u003e\n\u003cli\u003evan Hooidonk, R., Maynard, J. A., Liu, Y., \u0026amp; Lee, S.-K. (2015). Downscaled projections of Caribbean coral bleaching that can inform conservation planning. \u003cem\u003eGlobal Change Biology\u003c/em\u003e, \u003cem\u003e21\u003c/em\u003e(9), 3389\u0026ndash;3401. https://doi.org/10.1111/gcb.12901\u003c/li\u003e\n\u003cli\u003eYoung, C., Schopmeyer, S., \u0026amp; Lirman, D. (2012). A Review of Reef Restoration and Coral Propagation Using the Threatened Genus \u003cem\u003eAcropora\u003c/em\u003e in the Caribbean and Western Atlantic. \u003cem\u003eBulletin of Marine Science\u003c/em\u003e, \u003cem\u003e88\u003c/em\u003e(4), 1075\u0026ndash;1098. https://doi.org/10.5343/bms.2011.1143\u003c/li\u003e\n\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Coral restoration, ocean warming, Caribbean reefs, nursery design","lastPublishedDoi":"10.21203/rs.3.rs-7301952/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7301952/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe present study assesses the mortality or recovery of \u003cem\u003eAcropora cervicornis\u003c/em\u003e and \u003cem\u003eAcropora palmata\u003c/em\u003e coral fragments on \u003cem\u003ein-situ\u003c/em\u003e ocean nurseries during the fourth global coral bleaching event, 2023\u0026ndash;2024. Once primary reef-building corals of the Caribbean and tropical western Atlantic, \u003cem\u003eA. cervicornis\u003c/em\u003e and \u003cem\u003eA. palmata\u003c/em\u003e are now critically endangered species. Population management in the region has been attempted with \u003cem\u003ein-situ\u003c/em\u003e and land-based nurseries using the coral gardening restoration concept. However, ocean nurseries are not immune to environmental stressors, and the South Caicos, Turks and Caicos Islands, nursery sites experienced 81.1% mortality during the unprecedented marine heatwave. \u003cem\u003eA. cervicornis\u003c/em\u003e had a higher mortality rate (94.2%) than \u003cem\u003eA. palmata\u003c/em\u003e (74.7%), and the deepest nursery site at 12.1 m depth had the lowest mortality rate at 54.8%. Further, mortality rates did not differ significantly by nursery structure type. Findings suggest that deeper nurseries are more favorable for coral recovery and survival during heating events, providing restoration practitioners with a method of nursery protection as climate stress continues to intensify for coral reefs.\u003c/p\u003e","manuscriptTitle":"Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-18 08:26:30","doi":"10.21203/rs.3.rs-7301952/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d78074e1-48c3-4ea9-a21f-be8cb025521b","owner":[],"postedDate":"August 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-08T14:23:26+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-18 08:26:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7301952","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7301952","identity":"rs-7301952","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}