A new study has revealed surprising variations in heat tolerance among coral colonies, offering new insights into their potential survival as global ocean temperatures rise. Even corals of the same species, living side by side, exhibit significantly different responses to heat stress, highlighting the complexity of coral resilience.
The findings, published today, come as the world grapples with the impact of climate change on coral reefs. With the fourth global mass bleaching event recently declared and the Great Barrier Reef suffering five mass bleachings since 2016, these discoveries are crucial for future conservation efforts.
Variable Heat Tolerance in Coral colonies
The research focused on the tabular coral Acropora hyacinthus, a species highly vulnerable to heat waves but essential to the ecological balance of coral reefs. Scientists measured the bleaching thresholds of over 500 coral colonies from 17 reefs, observing how these corals responded to elevated water temperatures in a controlled experiment.
The results were striking: the amount of pigment retained by the corals a measure of how much algae remained in their cells varied widely under heat stress. While some colonies retained as little as 3% of their pigment, others held onto as much as 95%, indicating that certain corals can withstand extreme temperatures far better than others.
This variation was not limited to specific areas. Researchers found that 12 of the 17 reefs studied contained colonies with bleaching thresholds in the top 25%, suggesting that heat-tolerant corals are widespread across the Great Barrier Reef.
Nature Versus Nurture: Why Corals React Differently
The study sheds light on the factors that influence coral resilience. Corals handle stress differently due to a combination of genetic factors (“nature”) and environmental conditions (“nurture”). For instance, corals in the warmer waters of the northern Great Barrier Reef have adapted to handle higher temperatures but are already near their upper temperature limits. Meanwhile, southern corals, though less heat-tolerant overall, may have more room to adapt to future warming.
The genetic diversity found in corals across the Great Barrier Reef may hold the key to recovery and adaptation, while environmental factors such as water temperature, nutrient availability, and the health of symbiotic algae also play a crucial role.
Implications for Coral Reef Conservation
These findings could have a significant impact on coral reef restoration and conservation efforts. Selective breeding of heat-tolerant corals, based on the study’s results, is already underway. By breeding corals better suited to warmer waters, scientists hope to enhance the resilience of reefs in the face of climate change.
However, the study emphasizes that reducing global greenhouse gas emissions remains critical to ensuring the long-term health of coral reefs. While interventions like selective breeding may provide a temporary buffer, only dramatic reductions in carbon emissions can slow the pace of ocean warming and protect these fragile ecosystems.
In the fight to preserve coral reefs, both immediate interventions and long-term strategies will be necessary to give these vital ecosystems the best chance of survival in a warming world.
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Reference: https://www.sciencealert.com/scientist-find-corals-with-a-secret-that-could-aid-reef-conservation
