Chula Researcher Develops "Global-Warming Resistant Corals" for the Survival of Marine Ecosystems

BANGKOK, May 15, 2025 /PRNewswire/ -- Researchers at the Chulalongkorn Aquatic Resources Research Institute have developed guidelines to help corals adapt to global warming by gender-based artificial insemination and coral culture in high-temperature at birth to offer them a better chance for survival as "corals against global warming," while unveiling freezing technology for coral sperm cells to revive corals when the marine environment is restored.

Corals worldwide are experiencing degradation due to various factors, including human activities such as tourism, fisheries, and pollution, as well as the effects of climate change that can affect sea water temperature rises, causing coral bleaching. If the situation continues like this in the next 30 years, more than 90% of global corals may be at risk of extinction. When corals become extinct, the abundance and balance of marine ecosystems will also disappear, which will surely impact the food chain and climate systems.

Climate change is surely here to stay, and how long the Earth will take to bounce back is difficult to predict. So, all living organisms must adapt to survive global warming. The key challenge that many researchers are trying to answer is, "How do corals survive global warming?"

Professor Dr. Suchana Chavanich, Marine Science Department, Faculty of Science, Chulalongkorn University, Deputy Director of the Aquatic Resources Research Institute, Chulalongkorn University, and Deputy Director of Chula Unisearch, has been trying to find this answer, and according to several generations of coral breeding experiments since 2005 at the Marine Science Research Station and Koh Sichang Student Training Center, Chonburi Province, "Corals can thrive in global warming condition when they are raised in high temperature since birth."  This is the origin of the propagation and culture of "Corals Against Global Warming".

Coral Propagation with Artificial Insemination Techniques

Professor Dr. Suchana gave a brief introduction to corals and coral breeding: "Corals are invertebrates, living together in groups (colonies) along ocean reefs. Corals provide both habitats and food sources for various animals." In nature, corals reproduce in two ways:

1.  Sexual reproduction is when corals release eggs (spawn) and sperm to fertilize in the water during full moon nights. The chance of survival and growing is only 0.001% (risks of being eaten by marine animals and not fertilized). But the genetic diversity of baby corals is high.

2.  Asexual reproduction is a coral that is broken from the original coral, ends up in the right environment, and grows into a new colony of corals. This type of reproduction gives corals a 90% chance of survival, but the diversity of the genetics is low.

"The natural process of these two types of reproduction takes a long time. Particularly, in global warming conditions, sexual reproduction drastically dwindles. If we allow corals to naturally regenerate at their own pace, they may not be able to replace those corals that die of coral bleaching in time and risk extinction in the near future." Dr. Suchana said.

The Aquatic Resources Research Institute and the Faculty of Science of Chulalongkorn, in collaboration with the Plant Genetic Conservation Project Under The Royal Initiative of Her Royal Highness Princess Maha Chakri Sirindhorn and the Naval Special Warfare Command, Royal Thai Navy are trying to propagate corals with "artificial insemination techniques" that mimic the natural reproduction of corals.

Professor Dr. Suchana explained, "Researchers will collect both the eggs and sperm of the corals on full-moon nights when corals all over the sea are ready to breed by releasing sperm and eggs at the same time. These germ cells will then be fertilized in a tank to create coral embryos. Then terra cotta bricks are prepared to allow the coral embryo to perch and grow in the nursery for 2 years before bringing these corals back to the sea to grow for another 3 years. When the coral is 5 years old, the coral will be ready to spawn for the first time.  This method gives the corals a higher chance to survive and thrive."

Global Warming Simulation to Push Corals to Adapt Since Birth

Breeding to increase the coral population is not sufficient. The young corals must also be trained to increase their tolerance of global warming. For this, Dr. Suchana's research team will raise the coral embryoes born from artificial reproduction in the nurseries with a high temperature of 32-34 degrees Celsius (normal sea water temperature is 29-31 °C degrees Celsius).

According to the monitoring and observation, Dr. Suchana said, "After being released in the sea, the young corals that are resistant to global warming have been thriving, breeding, and reproducing like natural corals.  This was first seen in 2023!"

"Corals will simultaneously emit a large number of tiny pink buddle cells into seawater, and when this happens, a team of researchers will dive to harvest them and help continue breeding through artificial insemination to grow into the next generation of global-warming resistant corals."

Professor Dr. Suchana revealed that the cost of conserving corals using artificial insemination techniques and culturing them in a nursery for over 2 years can be quite high, i.e., USD 100 per baby coral, as opposed to the culture via coral fragmentation, which only costs USD 1 per coral.

"But looking at the survival rate from bleaching, it is worth the investment because we will get a new species of coral that has been trained to withstand rising sea water temperatures from global warming.", Prof. Dr. Suchana said.

Coral Conservation via Cryopreservation Technique

Even though the research team under the direction of Prof. Dr. Suchana has found ways to cultivate and increase the number of corals in the sea, the propagation of corals in nature still depends on the condition of the marine environment.

"Most corals reproduce only once a year, and only in favorable environments, such as temperature, full moon, and current flows. Currently, global warming has prevented corals from releasing their seasonal reproductive cells, making them vulnerable to future extinction."

With this concern, Prof. Dr. Suchana therefore collaborated with the Taiwanese research team (Dr. Chiahsin Lin) to experiment using cryopreservation technique to freeze the coral germ cells collected from the sea to conserve them for the future.

"All corals are important to marine ecosystems, so good coral conservation is about helping all types of corals reproduce and grow well. Collecting coral egg and sperm cells today requires collecting as many species as possible to be used in the future. When the environment is right, corals will come back to life." 

Professor Dr. Suchana added that the Thai research team is now successful in freezing the sperm, while egg freezing is still under experimentation, hoping that this may be one way to salvage the corals in this ever-changing global environment.

The Future of Coral Conservation

Dr. Suchana concluded that coral conservation cannot be done alone by scientists, but must be carried out in many dimensions, including coral reef restoration, reduction of pollution, and greenhouse gas emissions. Long-term budgetary support and participation from the public and private sectors, as well as the general public, will be the key to protecting and restoring corals in the future. With proper operation, corals may be able to recover and thrive as an important ecosystem of the sea.

View the photo album of this article at https://www.chula.ac.th/en/highlight/236355/

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