- SDGs14: Life Below Water -
A New Solution
If you have ever eaten yogurt or kimchi, then you’re probably familiar with the term probiotics. Probiotics are advantageous microorganisms that have been thoroughly researched for their benefits in human health and environmental preservation. They also offer potential advantages for corals and the ecosystems of coral reefs. However, corals around the world face numerous threats, including rising ocean temperatures and tissue loss disease outbreaks. Researchers have been exploring the potential use of probiotics to help mitigate some of these challenges and promote coral health and resilience.
To understand the scope of the benefits of probiotics, we must first graph the magnitude of the problem. Coral bleaching is a destructive occurrence caused by global warming and rising ocean temperatures that affect reefs all around the world, decreasing coral populations at rapid rates.
Scientists believe that the heat from global warming damages the photosynthetic apparatus of the algae, inducing the production of reactive oxygen species. Reactive oxygen species leak into the coral cells, overwhelming the antioxidant system and the principal protective mechanism of the cell, causing damage to the tissues of the coral polyps.
The photosynthetic algae that live in coral polyps produce more than 80% of the carbon compounds that corals use as a source of energy. They also contribute to the corals' distinctive hue. Corals give protection and nourishment in exchange. Coral reef ecosystems are built on this symbiotic interaction that keeps reefs stable (KAUST).
Probiotics and Bleaching
Any good news about coral reefs is welcome, as more coral reefs suffer from bleaching and mass extinction due to increased ocean temperatures and related climate change circumstances. A new study from King Abdullah University of Science and Technology (KAUST) on how coral microbiome manipulation elicits metabolic and genetic restructuring to mitigate heat stress and evade mortality shows how probiotics can be helpful protagonists in boosting coral health and preventing mortality in the face of environmental stressors. The study discovers that probiotics aid corals in recovering from thermal stress by promoting immunological functions that aid in microbiome reconstruction and reduce symptoms of post-heat stress disorder brought on by thermal stress.
Researchers from KAUST believe that the way probiotics protect corals from bleaching is by buying corals time to recover from tissue damage so that the photosynthetic algae will stay intact for a longer period of time or more quickly replenish after a bleaching event. Inspired by a study related to helping mangrove biomes recover from oil spills with probiotics, researchers from KAUST tried to treat coral bleaching with similar methods.
The team created a potent probiotic after studying multiple strains of coral-associated bacteria, selecting traits such as the ability to degrade reactive oxygen species, resistance to pathogens, and the generation of nutrients for corals. All of these beneficial traits are carefully selected to help increase the coral’s probability of survival from bleaching caused by heat trauma. The team then created two controlled aquarium environments with corals and administered heat stress upon the reefs. One environment was exposed to the engineered probiotic, while the other was not. Although all corals started bleaching during the first stages of the trial, most of the corals exposed to probiotics survived, while none of the other corals lived. These results perfectly depict the healing power and potential probiotics shown in combating the devastating effects of coral bleaching (KAUST).
Figure 1. Coral bleaching
Combatting Coral Diseases with Probiotics
Moreover, probiotics also show potential in the treatment of coral tissue loss diseases. Coral tissue loss diseases cause large chunks of living coral tissue to slough off, revealing the skeleton underneath. These diseases have become an increasingly problematic issue in oceans all around the world, causing widespread coral deaths.
In search of a solution, the Smithsonian Marine Station at Fort Pierce lab is experimenting with probiotics, hoping to provide insight into a possible method to combat tissue loss diseases. The researchers tried to isolate beneficial bacteria from corals that are naturally more resistant to tissue loss diseases, hoping that these bacteria may aid corals in battling this disease. One strain of bacteria has so far shown promise as a tissue loss disease therapy and is still being cultivated in the lab. This strain of bacteria produces antibacterial compounds that are effective in combating coral tissue loss diseases.
In addition to halting the current coral tissue infection, this medication may also strengthen the coral's immune system, increasing its ability to fight off future infections. Probiotic-treated corals placed next to infected corals in the lab also slowed the infection of those corals. This was caused by the coral’s own bacteria exchange system, spreading the engineered probiotic throughout the environment. This shows that probiotics might be able to protect large quantities of corals from illness (Smithsonian Marine Station).
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