Akari Otsuka holds a Bachelor of Marine Science from James Cook University, where they graduated with distinction. Her undergraduate was marked by significant academic achievements, including receiving the College of Science and Engineering Prize, Marine Statistics Award and the University Medal. Following her undergraduate studies, she completed an Honours project under the supervision of Professor David Bourne, where she explored the impact of dietary starch in feed on the gut microbiome of aquacultured Giant Grouper (Epinephelus lanceolatus), fostering a specialized interest in marine microbiology and the analysis of bacterial community compositions.

Friend or Foe: are common coral symbionts mutualists or parasites?

2026 to 2030

Project Description

This project aims to determine how seawater nutrients influence the frequency and characteristics of Coral Associated Microbial Aggregates (CAMAs) in coral tissues. Specifically, the research aims to map the abundance, size, and number of CAMAs across endoderm and ectoderm tissue layers in multiple coral species. The project seeks to link these spatial patterns to varying nutrient exposure regimes across a water quality gradient on the Great Barrier Reef (GBR).

Project Importance

Understanding complex bacterial-coral interactions is essential for effective reef conservation, yet the exact nature of these relationships remains poorly resolved. This project is critical because establishing whether CAMAs benefit corals or are a symptom of nutrient stress is vital for future reef restoration endeavors that rely on microbiome engineering and probiotics. By identifying how environmental stressors like eutrophication impact the coral holobiont, the research provides evidence-based insights to underpin coral resilience and inform management frameworks like the Reef 2050 Plan.

Project Methods

Coral fragments will be collected from reefs that represents a nutrient exposure gradient, categorised into inshore and mid-shelf sites. Fixed tissues will be paraffin-embedded, sectioned, and visualized using laser confocal fluorescence microscopy combined with fluorescence in situ hybridization (FISH) using probes specific to Endozoicomonas. Intact CAMAs will be excised using in situ laser capture microdissection (LMD) to allow for 16S rRNA gene profiling and metagenomic analysis. Moreover, advanced imaging techniques, including cryo-electron tomography (cryo-ET) and cryo-focused ion beam-scanning electron microscopy (cryo-FIB/SEM), will be employed to resolve the three-dimensional molecular architecture and ultrastructure of CAMA cellular components.

Project Results

The project expects to find that CAMA prevalence and abundance increase in corals sampled from nutrient-rich inshore environments compared to those from oligotrophic offshore reefs. It is anticipated that high N:P levels in seawater facilitate the development of these microbial aggregates.

Keywords

Bacteria,
Coastal development,
Controlled Environment,
Coral reefs,
Corals,
Genetics,
Manipulative experiments,
Microbial,
Microbiology,
Molecular techniques,
Pollution