the impact of anthropogenic stress on the coral immune system
Australian Institute of Marine Science, Australia
ARC Centre of Excellence for Coral Reef Studies & School of Marine and Tropical Biology, James Cook University, Australia
PhD research advisors: Prof. Bette L. Willis, Dr. Madeleine J.H. van Oppen, Dr. David G. Bourne and Dr. William P. Leggat
ARC Centre of Excellence for Coral Reef Studies & School of Marine and Tropical Biology, James Cook University, Australia
PhD research advisors: Prof. Bette L. Willis, Dr. Madeleine J.H. van Oppen, Dr. David G. Bourne and Dr. William P. Leggat
Coral reefs are vulnerable ecosystems that harbour 25% of all marine species and provide goods and services worth $375 billion annually. Despite the high natural, cultural and economic value of these ecosystems, human activities are a major threat to the persistence of coral reefs. Anthropogenic pressures, such as climate change, tourism, fishing, coastal development, eutrophication and sedimentation, are increasingly linked to the severe degradation of coral reefs worldwide as they can significantly affect the health of the coral animal and its microbial symbionts (termed the coral holobiont). To cope with stress, corals possess a suite of response mechanisms, including a complex innate immune system.
This project aimed to elucidate how corals use their immune system to respond to stress and how environmental factors and anthropogenic stress affect the coral holobiont's ability to exhibit a proper stress response. I conducted both field and aquarium-based studies and assessed the responses of the coral, the algal endosymbiont Symbiodinium and the coral-associated bacterial communities using physiological and molecular techniques, |
Coral disease is one of the major factors responsible for coral reef decline worldwide. The last few decades, disease prevalence has increased significantly, which is a result of increasing anthropogenic pressures.
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including pulse amplitude modulated fluorometry, targeted gene and protein expression analysis as well as full transcriptome analysis (RNA Seq), bacterial community composition analysis (16S rRNA gene amplicon sequencing) and advanced microscopy techniques (e.g. laser scanning confocal microscopy; fluorescent in situ hybridisation). Overall, temporal patterns in baseline levels of coral immune system components were established and found to be strongly modulated by environmental factors in various important reef-building coral species (A). Generally, corals are well equipped to cope with elevated environmental stress levels, but additional anthropogenic
Overview of the coral holobiont responses to environmental, biological and anthropogenic stressors investigated as part of this project. Overall, corals are very well equipped to handle biotic and environmental stress, but additional anthropogenic pressures overwhelm their capacity to do so.
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stressors, such as those associated with permanent tourist reef platforms, may overwhelm the coral immune system, resulting in coral disease (B). In the absence of anthropogenic stressors, corals can also efficiently respond to injury, exhibiting a dynamic immune response, involving various components of the immune system, that is sufficient to maintain healthy coral-associated bacterial communities and prevent microbial infection (C). Interestingly, elevated seawater temperatures appeared to have only a limited impact on this response. Under heat stress, corals were also found to exhibit a significant immune response involving a large suite of immune mechanisms, likely in response to a temperature-induced shift in the bacterial community (D). In addition, corals were found to be capable of distinguishing
between harmful and harmless bacteria and exhibit an immune response only to harmful bacteria, regardless of temperature (D). |