- Title
- The challenges and threats high island coral reef ecosystems face in the Anthropocene
- Creator
- Moriarty, Tess
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Anthropogenically driven climate change and land-based activities have caused detrimental impacts on coral reef ecosystems globally. Synergistically or independently, these anthropogenic activities can, for example, cause increased frequencies and prevalence of coral bleaching and coral disease. As a result, significant coral mortality was experienced in the Anthropocene. In order to safeguard coral populations and biodiversity, practitioners and reef managers have explored coral reef restoration as a tool to repopulate sites that suffered significant mortality and identify coral ecological or physiological characteristics that make them less vulnerable to such perturbations. The literature on the use of coral restoration practices is explored, and this thesis identifies the risk such projects could have on local and transplanted corals with respect to coral disease. The chapter explores current coral diseases, predominantly identified through visual cues such as lesions and pigmentation alterations. This area requires further research in the field. For this reason, distinguishing the correct disease and its etiology has been complex in the field, as many diseases can look similar to one another; however, the etiologies could be different. We explore what to do in the event of coral disease outbreaks in restoration projects and what to consider concerning minimising coral disease outbreaks. This thesis explicitly explores current anthropogenic impacts at the remote high-island coral reefs of Lord Howe Island and the Island of Hawaii. These islands provide two unique reef systems, Lord Howe Island, a well-protected island, with respect to its isolation and well-managed reef with minimal anthropogenic stresses, a site ideal for studying reef resilience with little direct anthropogenic pressures and the reef at Puakō on Hawaii, a well-developed reef site prone to direct anthropogenic impacts such as water pollution and fishing pressure. Using spatiotemporal surveys to quantify and identify the prevalence of coral disease within the Lord Howe Island lagoon, this thesis identified four coral diseases in the lagoon, affecting six coral genera with an overall 5 ± 1 % prevalence. During temporal disease surveys, a thermal anomaly induced a mass coral bleaching event causing up to 83 % of corals to bleach and 40 % mortality. The bleaching event impacted sites differently, with rapid mortality documented at one site, Sylphs Hole, and mortality not recorded until seven months after the peak thermal anomaly at Coral Gardens and North Bay. Coral bleaching also impacted coral species differently, with four (Stylophora pistillata, Pocillopora damicornis, Porites spp. and Seriatopora hystrix) of the six most prolific coral species recorded as the most susceptible to bleaching and mortality at Lord Howe Island. During these coral disease and coral bleaching surveys, we found that the usually thermally sensitive coral genera Acropora was visually resilient to the thermal anomaly with no bleaching recorded. However, the genera were more susceptible to coral disease, with three of the four coral diseases recorded in Acropora colonies. This research illustrated the importance of collating baseline coral disease records and long-term and longitudinal monitoring of thermal anomaly events to gather a more accurate account of the impacts of coral bleaching events on the reef community. The research at Lord Howe Island indicated that the remote reef was not protected from anthropogenic impacts and is vulnerable to climate change. Puakō, on the northwest of the island of Hawaii, has historically been impacted by heavy fishing pressure and poor water quality from septic and sewage systems. The microbiome of Porites lobata was explored at Puakō to investigate the impacts water quality has on the corals’ microbial community. Puakō corals illustrated weak signals for an association between poor water quality and differences in microbial communities between 12 sites. The corals had a relatively stable microbiome across the 12 sites, with only three sites signifying significant differences. Further exploration of the sites and pairing microbial samples with water quality testing would assist in understanding differences in microbial communities. Our findings suggest that coral species more prone to environmental perturbations might be better suited as indicator species for coral reef health. This thesis highlights the anthropogenic impacts remote reefs are currently experiencing and emphasises the importance of long-term monitoring programs to elucidate resilience and recovery. The research carried out in this thesis is of significant importance to understanding these reef systems and how different anthropogenic influences impact them in the face of a changing climate.
- Subject
- coral reefs; coral disease; climate change; resilience; refuge; coral mortality; World Heritage area; coral bleaching; Lord Howe Island; subtropical; Disease prevalence; World Heritage Listed; reef restoration; management; bioindicator; stable; Endozoicomonas; Puakō; Hawaii; water quality; bacteria; coral microbiome; Anthropocene; risk management; mortality; microbiome; diagnostics; health; marine park; high latitude reef
- Identifier
- http://hdl.handle.net/1959.13/1478581
- Identifier
- uon:50197
- Rights
- Copyright 2022 Tess Moriarty
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 6 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 768 KB | Adobe Acrobat PDF | View Details Download |