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Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba

The long-spined sea urchin Diadema antillarum controls reef dynamics by grazing on algae and increasing coral recruitment. Populations of Diadema never recovered after a mass-die off in 1983 and 1984, and numbers were further reduced by a more recent die-off in 2022. To restore grazing pressure and...

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Autores principales: de Breuyn, Mareike, van der Last, Alex J., Klokman, Oliver J., Hylkema, Alwin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10576963/
https://www.ncbi.nlm.nih.gov/pubmed/37846309
http://dx.doi.org/10.7717/peerj.16189
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author de Breuyn, Mareike
van der Last, Alex J.
Klokman, Oliver J.
Hylkema, Alwin
author_facet de Breuyn, Mareike
van der Last, Alex J.
Klokman, Oliver J.
Hylkema, Alwin
author_sort de Breuyn, Mareike
collection PubMed
description The long-spined sea urchin Diadema antillarum controls reef dynamics by grazing on algae and increasing coral recruitment. Populations of Diadema never recovered after a mass-die off in 1983 and 1984, and numbers were further reduced by a more recent die-off in 2022. To restore grazing pressure and thereby the resilience of Caribbean coral reefs, multiple Diadema restocking efforts have been performed. Although results vary, relatively low retention is one of the reasons restocking is not considered more often. If causes for the low retention can be identified, suitable measures may be able to increase restocking success. In this study, we monitored restocked lab-reared and wild juvenile Diadema on artificial reefs around Saba, Caribbean Netherlands. To assess the retention of Diadema over time, we conducted diver surveys and used underwater photo time lapse during daylight. Retention of uncaged lab-reared and wild Diadema decreased steadily with less than 30% surviving after 10 days. In total, 138 predator-prey interactions were recorded, of which 99% involved the queen triggerfish Balistes vetula, although other potential predators were present in the area. None of the recorded predator-prey interactions was successful, which suggests that artificial reefs with incorporated shelters may be suitable for juveniles as daytime refuge. However, Diadema that were more often attacked during the day were more likely to be absent the next morning. Because queen triggerfish often visited the experimental site in the first or last hour of daylight, it could be that they were more successful in their attacks when it was too dark to see anything on the photos and when Diadema came out to feed or to look for better shelter opportunities. If Diadema migrated off the artificial reef, they were probably predated during the process, because no Diadema were found on surrounding reefs. Wild Diadema were attacked significantly more often than lab-reared Diadema, possibly because the wild urchins were larger, but this did not significantly affect retention. Future restocking should be performed on natural or artificial reefs with deeper shelters, so Diadema can retract farther into their crevice, and should include night-time monitoring to identify the remaining unknown factors that cause low retention, including migration and nocturnal predation. This knowledge is urgently needed to coral reef managers so they can increase Diadema restocking success by selecting reefs with a lower predator density, protect urchins during an acclimatization period and/or conduct temporary predator control measures.
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spelling pubmed-105769632023-10-16 Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba de Breuyn, Mareike van der Last, Alex J. Klokman, Oliver J. Hylkema, Alwin PeerJ Animal Behavior The long-spined sea urchin Diadema antillarum controls reef dynamics by grazing on algae and increasing coral recruitment. Populations of Diadema never recovered after a mass-die off in 1983 and 1984, and numbers were further reduced by a more recent die-off in 2022. To restore grazing pressure and thereby the resilience of Caribbean coral reefs, multiple Diadema restocking efforts have been performed. Although results vary, relatively low retention is one of the reasons restocking is not considered more often. If causes for the low retention can be identified, suitable measures may be able to increase restocking success. In this study, we monitored restocked lab-reared and wild juvenile Diadema on artificial reefs around Saba, Caribbean Netherlands. To assess the retention of Diadema over time, we conducted diver surveys and used underwater photo time lapse during daylight. Retention of uncaged lab-reared and wild Diadema decreased steadily with less than 30% surviving after 10 days. In total, 138 predator-prey interactions were recorded, of which 99% involved the queen triggerfish Balistes vetula, although other potential predators were present in the area. None of the recorded predator-prey interactions was successful, which suggests that artificial reefs with incorporated shelters may be suitable for juveniles as daytime refuge. However, Diadema that were more often attacked during the day were more likely to be absent the next morning. Because queen triggerfish often visited the experimental site in the first or last hour of daylight, it could be that they were more successful in their attacks when it was too dark to see anything on the photos and when Diadema came out to feed or to look for better shelter opportunities. If Diadema migrated off the artificial reef, they were probably predated during the process, because no Diadema were found on surrounding reefs. Wild Diadema were attacked significantly more often than lab-reared Diadema, possibly because the wild urchins were larger, but this did not significantly affect retention. Future restocking should be performed on natural or artificial reefs with deeper shelters, so Diadema can retract farther into their crevice, and should include night-time monitoring to identify the remaining unknown factors that cause low retention, including migration and nocturnal predation. This knowledge is urgently needed to coral reef managers so they can increase Diadema restocking success by selecting reefs with a lower predator density, protect urchins during an acclimatization period and/or conduct temporary predator control measures. PeerJ Inc. 2023-10-12 /pmc/articles/PMC10576963/ /pubmed/37846309 http://dx.doi.org/10.7717/peerj.16189 Text en ©2023 de Breuyn et al. https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Animal Behavior
de Breuyn, Mareike
van der Last, Alex J.
Klokman, Oliver J.
Hylkema, Alwin
Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title_full Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title_fullStr Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title_full_unstemmed Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title_short Diurnal predators of restocked lab-reared and wild Diadema antillarum near artificial reefs in Saba
title_sort diurnal predators of restocked lab-reared and wild diadema antillarum near artificial reefs in saba
topic Animal Behavior
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10576963/
https://www.ncbi.nlm.nih.gov/pubmed/37846309
http://dx.doi.org/10.7717/peerj.16189
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