Coral Reefs in the Remote Indian Ocean Bounced Back to Life

According to recent study, coral reefs in distant or protected locations can recover swiftly following catastrophic coral bleaching episodes.

Researchers at the University of Exeter are looking at "reef carbonate budgets," or the net production or erosion of reef structure over time.

Coral bleaching

(Photo : GLENN NICHOLLS/AFP via Getty Images)

They surveyed 12 reefs in the remote Chagos Islands in the Indian Ocean before and after the worldwide coral bleaching event in 2015/16 to evaluate the effects of climate change on reef functioning.

The once-thriving reefs were "shrinking" in 2018, with coral cover and carbonate down the production by more than 70% and erosion mechanisms outpacing new coral development, as per ScienceDaily.

When the researchers returned in 2021, all of the reefs had begun to regenerate, albeit the rate varied depending on location.

Reefs demonstrated a swift shift back to positive development only six years after the bleaching event where essential coral species returned quickly and the actual physiological reef structure remained intact.

Warmer water temperatures lead corals to expel their symbiotic algae, causing them to become white. Corals can withstand this, but an excessive heat wave causes widespread mortality.

The speed with which a reef recovers is a significant measure of its health and resiliency.

These rather rising incidence of coral recruitment and rapid reconstruction of reef operations are a pleasant surprise, implying that this location has shown some adaptability to ongoing ocean warming thus far, according to lead author Dr Ines Lange, a postdoctoral research fellow in a multi-institutional project funded by the Bertarelli Program in Marine Science.

Corals in the Chagos Archipelago are expected to fully recover over the next several years if the region is spared from future maritime heating episodes.

Dr. Lange further remarked that the study reveals that in distant and protected places with no local influences like as fishing or land pollution, coral reefs and the critical services they serve may rebound rather fast, even after large-scale disruptions.

Accessibility to healthy coral communities and the preservation of a complex reef structure appear to hasten recovery, which may aid in the management of reefs under the danger of increased frequency of bleaching episodes expected for the near future.

The census-based ReefBudget approach, created by co-author Professor Chris Perry of the University of Exeter, was designed to quantify coral carbonate expenditures.

These carbonate budgets are critical indications of a reef's capacity to offer habitat for marine life, shelter coastlines from tidal energy, and assist reef islands in adapting to potential rising sea levels.

Read more: How are Coral Reefs Adapting to Survive the Changes in the Climate

How corals remember its past exposure?

Corals in the ocean have shown the capacity to "remember" their previous exposure to climate changes, allowing them to survive better during repeated extreme events, as per The Scientist.

Scientists are exploring the phenomena of so-called ecological memory in the experiment and have discovered various ways in which reefs may recall earlier response to heat stress.

Corals may also be capable of passing on their memories to their progeny, however the mechanism for this is unknown.

This process, in which a creature alters its reaction to previous abiotic stimuli, is known as "environmental memory," and scientists are striving to understand how and why certain corals have a stronger capacity for memory than others.

Related article: Marine Biologists are Making Efforts to Save Coral Reefs in Mariana Islands