Shifting the symbiotic algae they host, researchers discovered how some reefs in the tropical Pacific Ocean may sustain high coral cover into the second part of this century.
The results provide a glimmer of light in a frequently bleak picture of what lies ahead for coral reefs around the world.
Coral reefs in the eastern Pacific
Coral reefs are disappearing due to global warming.
Scientists think that some corals are becoming more tolerant to the heat by altering the symbiotic algae populations they host, which give them the energy they require to survive through photosynthesis, as per ScienceDaily.
Branching corals in the genus Pocillopora, which are crucial for the reefs in the area, are the main builders of shallow coral reefs in the eastern tropical Pacific Ocean.
The microscopic algae that they harbor in their tissue collect light to assist the coral in generating energy for growth.
When these symbiotic algae are gone, the coral starts to bleach and struggles to satisfy its energy requirements, which can frequently be fatal.
They examined data on temperature, coral cover, bleaching, and mortality during three ocean heatwaves: 1982 to 1983, 1997 to 1998, and 2015 to 2016, as well as information on the algal symbiotic community for the final two.
The analysis revealed that the 1982 to 1983 heatwave had a significant impact on the coral cover on the reef, but that the 1997 to 1998 and 2015 to 2016 El Niño events had less of an impact, particularly on corals in the genus Pocillopora, also referred to as cauliflower coral, the most common coral reef-building species in eastern tropical Pacific.
Researchers also confirmed the heat-tolerant alga Durusdinium glynnii becomes more prevalent in this lineage of corals during intense ocean heatwaves, enabling them to better tolerate periods of high temperatures.
The reefs that were primarily made up of Pocillopora corals and even that hosted this heat-tolerant alga have been found to be better able to survive and keep high levels of coral cover throughout the second half of the current century, suggesting that certain reef systems could be more resilient to warming than previously believed.
Symbiodinium protects coral reefs
According to research, coral reefs are made up of a variety of species, the majority of which have symbiotic interactions with algae, as per Aljazeera America.
Both species profit since the coral provides refuge and essential minerals for the algae, which in turn provides the sugars required for the diet of the algae.
Climate change is causing ocean temperatures to rise, which puts that beneficial relationship at risk.
The loss of algae brought on by heat stress frequently results in coral bleaching.
The survival of the reef is seriously threatened by the length and frequency of these heat-stress events.
Coral bleaching from warmer water temperatures has already been devastating.
However, scientists discovered that the Symbiodinium species of algae, which is present in Gulf coral, can adapt to those alterations.
It could withstand annual temperature changes of up to 20 degrees Celsius, or 68 degrees Fahrenheit, and maximum temperatures of 34 to 36 degrees Celsius.
Researchers suggested that some coral-algae partnerships might endure the circumstances anticipated to exist in many coral-containing waters by the end of the century.
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