Can algae save the world's corals?
Coral reefs are said to be among the most diverse marine habitats and are home to a wide variety of creatures. You may have eaten a fish yesterday that feeds on the creature. Also, there must be some people who have enjoyed snorkeling and diving in the sea with beautiful coral reefs. Coral reefs contribute $30 billion a year to the global economy, including fisheries and tourism, and are directly involved in the livelihoods of 500 million people.
But without immediate action to conserve coral reefs, 99% of the world's coral reefs will go extinct this century, a study from Climate Impact Models predicts.
Coral lives on zooxanthellae
Corals, which are animals, maintain their survival through a symbiotic relationship with unicellular algae called zooxanthellae (dinoflagellates of the genus Symbiodinium ). Zooxanthellae supply substances (photosynthetic products such as oxygen and nutrients) necessary for coral growth and formation of coral reefs to corals, and in return receive nitrogen, phosphorus, etc. necessary for photosynthesis from corals.
In addition to getting nutrition from zooxanthellae, it seems that they prey on zooplankton with their tentacles, but it is said that it is difficult to grow healthy with only the nutrition obtained from them.
Zooxanthellae and detached coral endings
In recent years, the coral bleaching phenomenon, in which the photosynthetic system of zooxanthellae is damaged due to the rise in water temperature accompanying global warming, and the coral skeleton becomes transparent due to the release from the coral, has spread to the seas around the world. there is Corals that depend on zooxanthellae for nutrition will eventually die if they lose their symbiotic relationship with the algae for an extended period of time.
Coral with symbiotic zooxanthellae (left) and bleached coral without zooxanthellae (right)
Source: https://oceanservice.noaa.gov/education/kits/corals/media/supp_coral02d.html
Is stress-resistant zooxanthellae the key to preventing coral bleaching?
Interspecies genetic diversity of zooxanthellae is known to play a major role in coral bleaching resistance. Researchers led by Dr. Rachel Levin at the University of New South Wales in Australia used sequencing data from zooxanthellae to increase stress tolerance in zooxanthellae. A genetic modification strategy for algae was established. The findings were published June 30, 2017 in the journal Front. Microbiol.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492045/
"Little is known about zooxanthellae, which denies information for improving reef conservation behavior." In order to advance the necessary research, we aimed to conduct a new genetic analysis of zooxanthellae and overcome the obstacle (establishment of genetic recombination technology),” said Rachel.・Mr. Levin explains the difficulties of zooxanthellae research.
Researchers have identified genes, such as antioxidant genes, that may prevent coral bleaching. "Genetically engineered zooxanthellae that are enhanced to maintain symbiosis with corals in a marine environment where water temperatures are gradually increasing suggest the potential to reduce global coral bleaching." they said.
However, when it comes to releasing genetically engineered zooxanthellae into the environment, "before field-based testing begins, extensive and rigorous studies of potential negative risks are absolutely necessary." emphasized.
Also, recently, researchers at The Pennsylvania State University in the United States have identified a new species of stress-tolerant zooxanthellae ( Symbiodinium glynnii ). It turns out that corals that cohabit with this type of zooxanthellae are robust and can withstand harsh environments for corals that cohabit with other zooxanthellae species.
Apparently, stress-tolerant zooxanthellae will be the key to saving corals.
References:
A super-algae to save our seas?
https://www.sciencedaily.com/releases/2017/07/170720095111.htm
Stan & Debbie Hauter. Coral Bleaching. What is Coral Bleaching and Why Does it Occur?
https://www.thespruce.com/coral-bleaching-2924018
Rachel A. Levin, Christian R. Voolstra, Shobhit Agrawal, Peter D. Steinberg, David J. Suggett, Madeleine JH van Oppen. Engineering Strategies to Decode and Enhance the Genomes of Coral Symbionts. Frontiers in Microbiology, 2017; 8 DOI: 10.3389 /fmicb.2017.01220
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492045/
Newly described algae species toughens up corals to endure warming oceans.
https://phys.org/news/2017-07-newly-algae-species-toughens-corals.htm
