Negligible Effect of Density on Coral Survivorship and Implications for Reef Restoration
| dc.contributor.advisor | Madin, Joshua | |
| dc.contributor.author | Rutenberg, Mariya | |
| dc.contributor.department | Oceanography | |
| dc.contributor.department | Global Environmental Science | |
| dc.date.accessioned | 2022-10-07T19:08:13Z | |
| dc.date.available | 2022-10-07T19:08:13Z | |
| dc.date.issued | 2022 | |
| dc.description.course | OCN 499 - Undergraduate Thesis | |
| dc.identifier.uri | https://hdl.handle.net/10125/102434 | |
| dc.publisher.place | Honolulu | |
| dc.subject | coral reefs | |
| dc.subject | climate change | |
| dc.subject | reef restoration | |
| dc.title | Negligible Effect of Density on Coral Survivorship and Implications for Reef Restoration | |
| dc.type | Thesis | |
| dcterms.abstract | Coral reefs and the ecosystem functions and services they provide are increasingly threatened by anthropogenic stressors. To counter these stressors, active reef restoration has become the emerging tool for reef scientists and managers to counteract coral loss at local scales. Currently, restoration focuses mostly on out planting corals in attempts to increase coverage and diversity to historical levels. However, there is only a basic understanding of the optimal sizes and densities of outplants that should be used for effective reef restoration. For instance, colony survivorship tends to be strongly associated with size. Thus, we believe that colonies grow fastest at low densities, where density-dependent processes like competition and disease are minimal. In this study, I use a meta-analysis and a field study to quantify the influence of coral density (or crowding) on colony survival. For the meta-analysis, I extracted data on the density and survivorship of corals from studies that measured both variables. For the field study, I used previously published data for 11 species from an eight-year demography study at Lizard Island on the Great Barrier Reef. For both data sets, I was able to quantify the relationship between density (individuals per meter) and survivorship (chance of surviving one year) by fitting linear models. For the field study, I was also able to include growth morphology (or growth form) as a covariate, which is traditionally thought to have a key effect on survivorship as density increases (i.e., some species are better competitors for space based on their shapes). However, I found that density had a negligible impact on coral survival in both sets of analyses, despite densities of up to 30 colonies per meter square and 100% crowding in the meta-analysis and field study, respectively. However, survivorship was indeed strongly related to growth form, where robust massive forms tended to survive better than branching and tabular forms. These results suggest that competition for space is not a key driver of survival, and that other factors such as mechanical vulnerability override density processes. I ran into several issues with the meta-analysis that limited the amount of data I could analyze. For example, population density was reported in a range of different and incompatible ways, including as coral cover, which cannot reveal the difference between a single large colony and multiple smaller colonies. I therefore suggest that future efforts that measure coral cover should also include population density to improve data synthesis for meta- analysis. Overall, my work suggests that restoration initiatives should outplant colonies at sizes that optimize survivorship, which differ among species, and that outplant densities have little effect on survival rates. | |
| dcterms.extent | 51 pages | |
| dcterms.language | English | |
| dcterms.publisher | University of Hawaiʻi at Mānoa | |
| dcterms.rights | All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner. | |
| dcterms.rightsHolder | Rutenberg, Mariya | |
| dcterms.type |
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