Corals have vital, complex relationships with microorganisms. Microscopic algal symbionts are well known for providing corals with most of their energy. However, corals also associate with other microorganisms such as bacteria whose benefits range from nutrient cycling to protection against pathogens.
Investigating how microscopic communities influence the health and resilience of coral is important to understand how reefs will fare in warming oceans caused by climate change. Science teams are also investigating if manipulating these communities can boost coral heat tolerance for reef restoration efforts.
Early but short-term success with bacterial manipulation for heat stress tolerance in corals
Manipulating bacterial microbiomes has improved stress tolerance of crops and disease resistance in endangered corals and frogs. Early studies aimed at improving the heat tolerance of corals through bacterial manipulation have shown some success. However, bacteria only persisted in the treated coral for the short-term - successful interventions to boost heat tolerance in corals must provide a benefit over the long term to be viable.
Seeking best bacteria and method for improved long-term heat tolerance
Our study seeks to identify bacteria and methods of inoculation to improve the heat tolerance of corals in the long term. Starting during the 2024 Great Barrier Reef spawning season, our experiment in the National Sea Simulator aims to:
- examine whether beneficial bacterial candidates derived from coral tissues can establish a long-lasting and viable symbiotic relationship with new coral hosts,
- identify which coral life stage enables integration of bacterial symbionts long-term,
- assess the localisation of administered bacteria within the receiving coral host.
Larvae and adults of the hard coral Acropora loripes will be inoculated with four bacterial candidates, all expected to provide benefits to coral during heat stress. Their uptake and viability within the corals will be compared over five months.
The findings of this study will provide critical steps towards developing a sustainable approach for long-term enhancement of coral bleaching resilience via bacterial manipulation.
The best future for coral reefs to be able to survive climate change requires a reduction in global greenhouse emissions to stabilise temperatures, best practice management of local pressures and the development of interventions to help boost climate tolerance and resilience for coral reefs.
Researchers involved
Dr. Talisa Doering (The University of Melbourne)
Dr. Katarina Damjanovic
Juntong Hu (The University of Melbourne)
Research support
The identification and characterisation of the bacterial candidates' work was funded by the Australian Research Council (FL180100036 to MJHvO) and the Environmental Microbiology Research Initiative Grant 2021 to TD. The bacterial inoculation experiment is funded by the Australian Institute of Marine Science and the University of Melbourne.
This page was published in October 2024
Feature image: Justin Maire
