In 2015, amidst a marine heatwave, Barott’s team tagged numerous coral colonies, initiating a study on coral adaptability. Their focus: the rice coral (Montipora capitata) and finger coral (Porites compressa), two dominant species in the region. Over the years, multiple heatwaves provided a unique opportunity to observe coral responses, revealing both resilience and vulnerability.

Acclimatization

Corals, colonial marine invertebrates, rely on a symbiotic relationship with algae for survival. However, disturbances like temperature shifts can disrupt this delicate balance, leading to coral bleaching—a critical threat to reef ecosystems. The researchers meticulously tracked over 40 coral colonies, discovering variations in resilience. While some corals displayed persistent pigmentation, indicating thermal tolerance, others exhibited signs of acclimatization, adapting to successive heatwaves.

Environmental memory

The study unveiled the concept of “environmental memory,” where corals retain resilience from prior stress events. This phenomenon parallels human adaptation to exercise, suggesting corals can acclimate to recurring stressors. However, resilience varied between species, with rice coral showing prolonged recovery periods.

Despite signs of resilience, challenges persist. The ongoing El Niño cycle threatens warmer ocean temperatures, emphasizing the urgency of coral conservation. Future research aims to unravel genetic and physiological factors driving resilience, crucial for predicting coral survival in a changing climate.

Global significance

These findings hold global significance, guiding conservation efforts and informing policymakers. Protecting resilient coral species is paramount for preserving marine biodiversity and the vital services coral reefs provide. However, achieving zero carbon emissions remains imperative for the long-term survival of coral ecosystems.

As Barott stressed, preserving coral reefs is essential for cultural heritage and ecosystem health. Urgent action is needed to address losses and safeguard these invaluable marine ecosystems for future generations.

“Getting to zero carbon emissions is absolutely essential for the survival of coral reefs into the future,” said Barott. “So, even though we have signs of resilience, if the only species left is Porites compressa, we’re not going to have the amount of biodiversity and services from these ecosystems that a lot of people rely on, both for their cultural value as well for nutrition. Corals can take years to reach sexual maturity, and some reefs can take thousands of years to fully form, so addressing these losses is urgent and pressing if we want to maintain coral reef ecosystems as we know them.”