New studies have uncovered previously unknown differences in the heat tolerance of coral on the Great Barrier Reef, suggesting that the genetic diversity within corals may play a crucial role in their recovery and adaptability. Researchers assessed the bleaching limits of over 500 colonies of the table coral, Acropora hyacinthus, using a portable experimental system deployed at sea across 17 reefs within the Great Barrier Reef. They discovered that heat-resistant corals were present in nearly all the reefs examined.
Recent findings from Southern Cross University reveal previously unrecognized differences in heat tolerance among corals on Australia’s Great Barrier Reef, offering optimism that the genetic diversity of corals might be essential in supporting their recovery and adaptability.
An upcoming study, to be published at 10am BST on Monday, September 23, 2024, in Communications Earth and Environment, involved researchers measuring the bleaching thresholds of more than 500 colonies of the table coral, Acropora hyacinthus, with a portable system tested at 17 reefs across the Great Barrier Reef.
The research was spearheaded by Melissa Naugle, a PhD candidate from Southern Cross University, collaborating with teams from Southern Cross University, the Australian Institute of Marine Science (AIMS), the University of Queensland, and the Research Institute for Development in New Caledonia as part of the Reef Restoration and Adaptation Program (RRAP).
Melissa stated, “We discovered heat-tolerant corals in nearly all the reefs investigated, indicating that corals throughout the Great Barrier Reef may possess genetic resources critical for their conservation and restoration.”
“This is a significant finding for corals facing their fourth global mass bleaching event and record summer temperatures in the Great Barrier Reef. The natural variation in heat tolerance is vital for corals’ adaptation to climate change and for the effectiveness of conservation efforts.”
These findings were backed by another recent study by co-author Hugo Denis, also a PhD candidate at Southern Cross University, who identified widespread variations in heat tolerance in a different coral species.
The implications of this research are significant for the future of coral reefs.
Dr. Line Bay, co-author and Senior Principal Research Scientist at AIMS, noted, “Variations among individual corals provide the necessary diversity for natural selection to result in future generations of more heat-tolerant corals.”
Dr. Cedric Robillot, Executive Director of the Reef Restoration and Adaptation Program, remarked, “This research emphasizes the existence of naturally heat-tolerant corals that RRAP can focus on as part of a significant reef restoration and conservation initiative, aimed at safeguarding this vital ecosystem from the rising ocean temperatures linked to climate change.”
Dr. Emily Howells, co-author and Senior Research Fellow at Southern Cross University, indicated, “Variations in heat tolerance could be beneficial for conservation programs like selective breeding, which may hasten adaptation to produce offspring that are more suited to warmer waters. However, the success of this approach depends on how much of the observed heat tolerance variation is associated with inherited genetic traits.”
The corals identified as most heat tolerant in this study are currently under evaluation in a selective breeding trial through the Reef Restoration and Adaptation Program.
The study not only highlighted the extent of coral heat tolerance variation but also explored the factors that contribute to this difference.
Melissa explained, “In this paper, we examined various environmental factors that influence heat tolerance, such as thermal history, nutrient levels, and the symbiotic algae residing within coral tissues.”
While the study found that factors like sea temperatures significantly impacted heat tolerance, a noticeable portion of the variation couldn’t be explained by environmental conditions and likely stemmed from genetic differences among individual corals.
“Our next step involves analyzing DNA sequencing data from these corals to identify gene variants connected to heat tolerance. This will deepen our understanding of how natural coral populations can adapt and support selective breeding efforts,” added Melissa.
“Although selective breeding and other restoration initiatives may bolster coral populations, mitigating greenhouse gas emissions remains the most crucial step to ensure the best possible future for coral reefs.”
