Research News

Hawaiian corals show surprising resilience to warming oceans

22-month study provides realistic conditions, scientists say

A long-term study of Hawaiian coral species offers a surprisingly optimistic view of how they might survive warmer and more acidic oceans resulting from climate change.

Researchers found that three coral species studied experienced significant mortality under conditions simulated to the approximate ocean temperatures and acidity expected in the future -- up to about half of some of the species died.

But the fact that none of them completely died off -- and some were thriving by the end of the study -- offers hope for the future of corals, according to Rowan McLachlan of Oregon State University. "We found surprisingly positive outcomes in our study. We don't get a lot of that in the coral research field when it comes to the effects of warming oceans."

While the findings are optimistic, they are also more realistic than previous studies, said study senior author Andrea Grottoli of The Ohio State University. The study lasted 22 months, which is much longer than most similar research, which often spans days to up to five months.

"There are aspects of coral biology that take a long time to adjust," Grottoli said. "There can be a dip when they are faced with stressors, but after enough time corals can recalibrate and return to a normal state." The U.S. National Science Foundation-supported research was published in the journal Scientific Reports.

In the study, the researchers collected samples of the three most common coral species in Hawaii: Montipora capitata, Porites compressa and Porites lobata.

Results showed that warming oceans will hurt these coral species: 61% of corals exposed to the warming conditions survived, compared to 92% of those exposed to current ocean temperatures.

The two Porites species were more resilient than M. capitata in the combined warming and acidification condition. Over the course of the study, survival rates were 71% for P. compressa, 56% for P. lobata and 46% for M. capitata.