An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system
Coral and macroalgae are the two main habitat forming competitors in the reef benthic environment. Interactions between these organisms are mostly negative for both species, however corals can be outcompeted by macroalgae, suffering pathogenic shifts in their microbiome, tissue damage and decreased...
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| Format: | Thesis-Doctor of Philosophy |
| Language: | English |
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Nanyang Technological University
2024
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| Online Access: | https://hdl.handle.net/10356/179384 |
| _version_ | 1811692396615827456 |
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| author | Tang, Peggy Pei Yi |
| author2 | Case Rebecca Josephine |
| author_facet | Case Rebecca Josephine Tang, Peggy Pei Yi |
| author_sort | Tang, Peggy Pei Yi |
| collection | NTU |
| description | Coral and macroalgae are the two main habitat forming competitors in the reef benthic environment. Interactions between these organisms are mostly negative for both species, however corals can be outcompeted by macroalgae, suffering pathogenic shifts in their microbiome, tissue damage and decreased coral polyp fecundity. In recent decades, a combination of climate change and other anthropogenic factors have resulted in reduced reef resilience and increasing macroalgal-dominated reef systems worldwide. However, resilient coral reef systems thrive in some parts of the world, including Singapore, despite being subjected to long-term sedimentation and thermal stress with an absence of shifts towards a macroalgal-dominant reef system.
The coral holobiont consists of the coral itself, (which acts as a host to the Symbiodiniaceae communities), and its microbiome (bacteria, archaea, fungi, and viruses). Its microbiome is essential to coral health, and it changes during macroalgal contact. The aim of our study is to characterize the bacterial microbiome’s dynamic response during macroalgal contact in common Singaporean coral species and possible changes in the Symbiodiniaceae communities and coral host transcriptome (i.e., up and down shifts in gene transcription). Mesocosm experiments were carried out on the corals Merulina ampliata, Montipora stellata and Pocillopora acuta, with a combination of amplicon sequencing of the V4 region of the 16SrRNA gene, ITS2 sequencing, and transcriptomics used to characterize changes during coral-macroalgal contact in the coral microbiome, Symbiodiniaceae communities and coral gene expression.
In our study, it was observed that the coral microbiomes were relatively stable at both alpha- and beta- diversity levels during macroalgal contact. At the ASV level, however, dynamic changes in relative abundances of bacterial species linked to disease in past studies (e.g., Vibrio sp., Family Rhodobacteraceae), those with potential beneficial effects (e.g., Erythrobacter sp.), and predatory bacterial species (e.g., Peridibacter sp. and Halovorax sp.) were observed, reflecting active participation of the coral microbiome in maintaining coral health during macroalgal contact. However, biogeographical variations were also observed between these changes, which could result in varying reef resilience against macroalgal contact at different locations.
For the Symbiodiniaceae, no major changes to the clades in different coral species occurred during macroalgal contact. Instead, the distribution of the Symbiodiniaceae was based on colony and coral species. These were dominated by clades C (Cladocopium sp.) and D (Durusdinium sp.), which were previously linked to environmental resilience in past studies, highlighting the possible influence of the Symbiodiniaceae in mitigating stress responses against macroalgal contact. Although no clear patterns were observed with coral host gene transcription due to possible genotype variations within the corals, some genes associated with various functions, including transcriptional, biocalcification and signal recognition functions, were found to be upregulated during macroalgal contact. These also varied between coral species, location and type of macroalgal contact, implying possible variations in the underlying mechanisms and degree of resilience against macroalgal contact.
These observations between the coral microbiome, Symbiodiniaceae and the coral host demonstrated the connectedness of the members of the coral holobiont in resilience against macroalgal contact. Better understanding of these underlying interactions may be helpful for possible mitigation of macroalgal overgrowth issues in reef conservation. |
| first_indexed | 2024-10-01T06:35:07Z |
| format | Thesis-Doctor of Philosophy |
| id | ntu-10356/179384 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T06:35:07Z |
| publishDate | 2024 |
| publisher | Nanyang Technological University |
| record_format | dspace |
| spelling | ntu-10356/1793842024-09-04T07:56:36Z An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system Tang, Peggy Pei Yi Case Rebecca Josephine School of Biological Sciences St John's Island National Marine Laboratory National Research Foundation National Parks Board Singapore Centre for Environmental Life Sciences and Engineering (SCELSE) Staffan Kjelleberg rj.case@ntu.edu.sg, LASKjelleberg@ntu.edu.sg Earth and Environmental Sciences Medicine, Health and Life Sciences Coral microbiome Marine holobiont Marine microbiology Reef resilience Urbanized reefs Pocillopora acuta Merulina ampliata Montipora stellata Lobophora Coral macroalgal interactions Singapore Coral and macroalgae are the two main habitat forming competitors in the reef benthic environment. Interactions between these organisms are mostly negative for both species, however corals can be outcompeted by macroalgae, suffering pathogenic shifts in their microbiome, tissue damage and decreased coral polyp fecundity. In recent decades, a combination of climate change and other anthropogenic factors have resulted in reduced reef resilience and increasing macroalgal-dominated reef systems worldwide. However, resilient coral reef systems thrive in some parts of the world, including Singapore, despite being subjected to long-term sedimentation and thermal stress with an absence of shifts towards a macroalgal-dominant reef system. The coral holobiont consists of the coral itself, (which acts as a host to the Symbiodiniaceae communities), and its microbiome (bacteria, archaea, fungi, and viruses). Its microbiome is essential to coral health, and it changes during macroalgal contact. The aim of our study is to characterize the bacterial microbiome’s dynamic response during macroalgal contact in common Singaporean coral species and possible changes in the Symbiodiniaceae communities and coral host transcriptome (i.e., up and down shifts in gene transcription). Mesocosm experiments were carried out on the corals Merulina ampliata, Montipora stellata and Pocillopora acuta, with a combination of amplicon sequencing of the V4 region of the 16SrRNA gene, ITS2 sequencing, and transcriptomics used to characterize changes during coral-macroalgal contact in the coral microbiome, Symbiodiniaceae communities and coral gene expression. In our study, it was observed that the coral microbiomes were relatively stable at both alpha- and beta- diversity levels during macroalgal contact. At the ASV level, however, dynamic changes in relative abundances of bacterial species linked to disease in past studies (e.g., Vibrio sp., Family Rhodobacteraceae), those with potential beneficial effects (e.g., Erythrobacter sp.), and predatory bacterial species (e.g., Peridibacter sp. and Halovorax sp.) were observed, reflecting active participation of the coral microbiome in maintaining coral health during macroalgal contact. However, biogeographical variations were also observed between these changes, which could result in varying reef resilience against macroalgal contact at different locations. For the Symbiodiniaceae, no major changes to the clades in different coral species occurred during macroalgal contact. Instead, the distribution of the Symbiodiniaceae was based on colony and coral species. These were dominated by clades C (Cladocopium sp.) and D (Durusdinium sp.), which were previously linked to environmental resilience in past studies, highlighting the possible influence of the Symbiodiniaceae in mitigating stress responses against macroalgal contact. Although no clear patterns were observed with coral host gene transcription due to possible genotype variations within the corals, some genes associated with various functions, including transcriptional, biocalcification and signal recognition functions, were found to be upregulated during macroalgal contact. These also varied between coral species, location and type of macroalgal contact, implying possible variations in the underlying mechanisms and degree of resilience against macroalgal contact. These observations between the coral microbiome, Symbiodiniaceae and the coral host demonstrated the connectedness of the members of the coral holobiont in resilience against macroalgal contact. Better understanding of these underlying interactions may be helpful for possible mitigation of macroalgal overgrowth issues in reef conservation. Doctor of Philosophy 2024-08-01T06:01:00Z 2024-08-01T06:01:00Z 2023 Thesis-Doctor of Philosophy Tang, P. P. Y. (2023). An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/179384 https://hdl.handle.net/10356/179384 10.32657/10356/179384 en MSRDP-P03 This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University |
| spellingShingle | Earth and Environmental Sciences Medicine, Health and Life Sciences Coral microbiome Marine holobiont Marine microbiology Reef resilience Urbanized reefs Pocillopora acuta Merulina ampliata Montipora stellata Lobophora Coral macroalgal interactions Singapore Tang, Peggy Pei Yi An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title | An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title_full | An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title_fullStr | An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title_full_unstemmed | An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title_short | An integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| title_sort | integrated approach to study the effects of macroalgal interactions on the coral microbiome in an urbanized reef system |
| topic | Earth and Environmental Sciences Medicine, Health and Life Sciences Coral microbiome Marine holobiont Marine microbiology Reef resilience Urbanized reefs Pocillopora acuta Merulina ampliata Montipora stellata Lobophora Coral macroalgal interactions Singapore |
| url | https://hdl.handle.net/10356/179384 |
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