Coral disease survey in Taiwan

• Main Authors: Huang, Ching-Yun, 黃靖雲
• Other Authors: Hwang, Jiang-Shiou
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/u2w255

碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 107 === Coral diseases have caused a substantial decline in reef-building corals’ biodiversity and abundance. It can cause progressive tissue loss and/or affect coral growth, reproductive capacity, recruitment, species diversity and the abundance of reef-associated organisms. While coral disease research has increased over the last four decades, very little is known about coral diseases in Taiwan. This study is the first one aims to know the status of coral diseases in Taiwan. We applied belt-transects at multiple localities in Northeast coast, East Coast, Kenting, Green Island, Orchid Island, and Southern Islands from April to August in 2018 for the spatial survey, and conducted another cross-seasonal survey from October to November in 2018 in Northeast coast, Kenting, and Green Island. Total applied 31 transects, surveyed 3840m2 area and examined 20709 coral colonies. During the surveys, we identified 9 coral diseases, including black band disease (BBD), BBD-like syndrome (BBD-like), other cyanobacteria syndrome (CY), skeletal eroding band (SEB), ulcerative white spots (UWS), growth anomalies (GAs), white syndrome (WS), flatworm infestation (Fl), and pigmentation response (PR). The highest overall disease prevalence presented in Northeast coast (7.28%±3.20%), Kenting (8.62%±5.48%), Green Island (8.03%±3.85%), and Orchid Island (7.83%±2.93%). A little bit lower on the East coast (5.30%±3.60%). The Southern Islands was the lowest (2.15%±2.65%). And each survey site had a particular disease distribution pattern. We also found that coral diseases have their own preferred host and mainly affect 5 coral families, Acroporidae and Poritidae corals are especially sensitive to diseases. Coral coverage and diversity in the community also play a role in disease distribution. Higher coral coverage may accelerate the pathogen infection while the diversified community may provide some protection from the infection. This study also tried to evaluate the stress level in the coral community. It ends up finding the higher the stress level, the higher the PR prevalence which reflects inflammation in coral tissue, but the number of coral diseases can be lesser in the certain community. These findings led to the conclusion that coral disease distribution can be affected by several factors such as coral community composition, coral coverage and diversity, disease-host preference and the stressed condition in the coral community. Finally, we developed a new putative model to explain the interaction between the coral community, disease, and the environment. Under normal status, each locality hosts a certain coral community because of its geographical and oceanographic characteristics, and the coral community will influence the disease distribution pattern. When the season changes, some environmental variables also shift. The coral community may need to adapt itself to the habitat by phase-shifting from one stable state to another alternative stable state, and it may able to shift back to the original stable state when the variables back to the normal level. If there are some stressors present, the coral community may shift to one another alternative stable state and need to spend more energy to shift back to the original stable state. If the stress level in the coral community keeps leveling up, it may result in some long-term parameter perturbations and ends up in state shift, meaning the community composition is changed. The community shifts to another state, which is also stable but, because it corresponds to different parameter values, the associated dynamics are different.