At our National Sea Simulator, scientists are studying baby coral, particularly heat-tolerant corals and large-scale coral aquaculture. This research is crucial, especially considering the regrowth of coral on the Great Barrier Reef after significant losses in 2016 and 2017 due to above-average water temperatures. However, this regrowth can largely be attributed to luck, as the reef narrowly avoided extensive coral deaths during mass bleaching events in 2020 and 2022 when temperatures cooled just in time.
Unfortunately, the luck of the Great Barrier Reef may soon run out, as hotter El Niño conditions are returning, resulting in warmer ocean temperatures. Recent months have seen record-breaking global temperatures, leading to bleaching in reefs around the world, including Florida, the Caribbean, and parts of the Pacific. With the looming southern summer, concerns about the reef’s survival are mounting.
While controlling emissions is vital for the reef’s long-term health, there are additional ways to support its resilience. In a newly published paper in Science, we outline methods for accelerating the natural evolution of heat-tolerant corals, developing next-generation aquaculture techniques for rearing large numbers of baby corals, and engaging in collaborative decision-making with First Nations groups to strategically place these corals on the Great Barrier Reef.
Advancing Heat-Tolerant Coral Breeding
Coral species differ in their ability to tolerate heat, with some being more resilient than others. Bleaching thresholds have actually increased globally by 0.5℃ in the past decade, indicating that reefs are slowly adapting to higher temperatures. The loss of more sensitive species and colonies may be contributing to this increased tolerance.
Within species, individual corals in warmer waters are typically more heat-tolerant than those in cooler waters. By understanding the reasons behind these differences and how they can be inherited, we can identify corals with the best adaptation potential and selectively breed them for heat tolerance.
The microbiome of coral plays a crucial role in its heat tolerance. Certain symbiotic algae, such as Durusdinium, can enhance the coral’s heat tolerance, but at the cost of reduced growth. On the other hand, other coral-associated algae, like Cladocopium, can improve heat tolerance without compromising other survival traits. By inoculating selectively bred corals with algae from Cladocopium, we can achieve greater heat tolerance in the offspring. These methods have shown promise in laboratory testing and have the potential for large-scale production.
To identify naturally resilient corals during bleaching events or rapid heat stress experiments, we are developing tools that can detect these individuals. By analyzing coral DNA, we can also identify genetic markers associated with heat tolerance and monitor how genetic diversity and heat tolerance are maintained in aquaculture facilities and field conditions.
Scaling Up Coral Aquaculture
As this year’s marine heat waves break records, scaling up coral restoration and adaptation techniques become more critical. Historically, coral breeding has been done manually in small laboratory aquarium facilities, which is slow and expensive. However, advancements in coral aquaculture in Townsville have the potential to significantly boost production rates while reducing costs.
To produce heat-tolerant corals at scale, selected baby corals are settled on small tabs in modular sheets. These individual tabs, each hosting a thriving baby coral, are then attached to specially designed fist-sized structures that protect them in the ocean. This significantly increases their survival rate once placed on the reef. We are currently testing these technologies by deploying these structures in carefully chosen locations on the Great Barrier Reef, where the corals can grow and eventually reproduce. As production scales up, we will be able to deliver large numbers of structures without divers, using boats or robots. Automation will play a crucial role in streamlining coral rearing processes.
Ensuring Successful Conservation Efforts
Ensuring the success of heat-resistant baby corals requires robust ecological models and decision-making processes that consider economic, social, and environmental factors. Collaborating with Traditional Owners is vital in achieving meaningful partnerships and combining conventional scientific knowledge with traditional knowledge for better insights.
For instance, the marine management of Groote Eylandt in Australia’s north now incorporates maps produced by scientists collaborating with Anindilyakwa people, combining local knowledge, in-water surveys, and satellite data. As large-scale restoration and adaptation efforts progress, First Nations rangers in Australia could serve as a community-based workforce for management and conservation activities, especially in remote regions. Traditional Owners can also play essential roles in monitoring the progress of conservation initiatives.
In the face of accelerated disruptions due to global heating, traditional conservation approaches are no longer sufficient to protect ecosystems. We must take action to support the resilience of natural systems. Although time is running short, the advancements in accelerated evolution and automated aquaculture offer hope for coral’s survival in increasingly hotter seas.
About the article
This article was originally published on The Conversation. The original article can be accessed here.
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Shambhu Kumar is a science communicator, making complex scientific topics accessible to all. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
