In a paper published in Nature, scientists explain how certain types of coral escaped a known heatwave in Hawaii, one of the planet's most environment sensitive areas.
Coral have survived heatwaves for decades, the ocean continues to endure cycles of high temperatures, and new methods of assisting coral may be created. Many environmental initiatives have centered on reducing local stressors, relying on the belief that such efforts would improve coral reef resistance to heat stress. However, the paper suggests data is inconsistent with clear observational evidence supporting such an impact. In reality, it has been argued that hot environments might increase the amount of thermal tolerance.
Coral reefs perform many essential roles, including supplying shelter for numerous animals to even shielding shorelines from erosion. Similar to coral reefs, healthy reefs act as an essential source of food and income for hundreds of millions of citizens in colder tropical islands, many of whom rely heavily off of fish that reside inside and around reefs.
The mechanism originally found were discovered in corals that weren't really at a high risk of extinction. This pathway is also important even if it does not function in all cases.
The pressing environmental health threats associated with climate change have placed the long term sustainability of the world's coral reefs at danger. Even though coral bleaching continues, new research promotes optimism as several corals manage to withstand a recent and globally unparalleled heatwave.
“Understanding how some corals can survive prolonged heatwaves could provide an opportunity to mitigate the impact of marine heatwaves on coral reefs, allowing us to buy time as we work to limit greenhouse gas emissions,” says lead author Danielle Claar as quoted in Futurity. Claar is a postdoctoral researcher at the University of Washington who completed the work as doctoral student at the University of Victoria.
In the 2015-2016 El Niño event, heat stress from the event caused widespread coral bleaching and mortality on reefs all over the world. The report presents the observations made by an international research team as they monitored hundreds of coral colonies on reefs around Christmas Island (Kiritimati) in the Pacific Ocean, where the heatwave lasted an incredible 10 months.
The warming of the oceans threatens to trigger a worldwide extinction of corals because corals are particularly susceptible to the temperature of their surrounding waters. Warming waters will cause a coral bleaching where the coral's symbiotic algae turn whitish when they remove the food-producing algae that reside in their tissues. Several prolonged bleaching events (from imbalances in the ecosystem) sometimes lead corals to die from malnutrition, but they will rebound if they reclaim their food supply within a few weeks.
Interestingly, there is a single case study where coral regeneration from bleaching has only ever been observed after heat stress subsides. Owing to the will frequency and length of heatwaves, which are expected to continue to rise in both frequency and duration, the amount required to regenerate for the coral to thrive will be much more drastic than before, and if it cannot recover, it will perish.
The coral researchers found that these corals only displayed stress tolerance if the coral were not already subject to other human-caused stressors, such as water contamination. These new findings show that a reduction of human impacts on the ecosystem can help corals survive climate change.
“We've found a glimmer of hope that protection from local stressors can help corals,” said Julia Baum, a University of Victoria aquatic biology undergraduate, in the "Calgary Herald" newspaper.