VNR: Unprecedented acidification ahead for corals in Hawai‘i waters

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***SUGGESTED VOSOT SCRIPT BELOW***

Across the globe, oceans are acidifying as they absorb carbon dioxide from the atmosphere, threatening coral reefs and many other marine organisms. A new study, led by oceanographers at the University of Hawai‘i at Mānoa, revealed that unprecedented levels of ocean acidification are expected around the main Hawaiian Islands within the next three decades.

Increased ocean acidification has the potential to harm marine life by weakening the shells and skeletons of organisms such as corals and clams, amplifying the effects of existing stressors, and threatening ocean-based ecosystems. However, researchers have hope, as some organisms have shown signs of adapting to the changing waters. The study helps researchers, conservationists and policymakers understand the future challenges facing Hawai‘i’s coral reefs and provides information for preserving these critical ecosystems for future generations.

Researchers within the laboratory group of Brian Powell, professor in the Department of Oceanography at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), used advanced, fine-scale computer models to project how ocean chemistry around the main Hawaiian Islands might change over the 21st century under different climate scenarios based on how much carbon dioxide societies continue to emit. 

“We found that ocean acidification is projected to increase significantly in the surface waters around the main Hawaiian Islands, even if carbon emissions flatline by mid-century in the low emission scenario,” said Lucia Hošeková, lead author of the paper and research scientist in SOEST. “In all nearshore areas these increases will be unprecedented compared to what reef organisms have experienced in many thousands of years.”

Emissions shape coral reef future

The extent and timing of these changes vary depending on the amount of carbon added to the atmosphere. In the high‐emission scenario, the team found that ocean chemistry will become dramatically different from what corals have experienced historically, potentially posing challenges to their ability to adapt. Even in the low‐emission scenario, some changes are inevitable, but they are less extreme and occur more gradually. 

The team calculated the difference between projected ocean acidification and acidification that corals in a given location have experienced in recent history. They refer to this as ‘novelty’ and discovered that various areas of the Hawaiian Islands may experience acidification differently. Windward coastlines consistently exhibited higher novelty, that is, future conditions deviate more dramatically from what coral reefs have experienced in recent history.

“We did not expect future levels of ocean acidification to be so far outside the envelope of natural variations in ocean chemistry that an ecosystem is used to,” said Tobias Friedrich, study co-author and research scientist in the Department of Oceanography. “This is the first ocean acidification projection specifically for Hawaiian waters to document that.”

Corals potential to adapt

Previous studies have shown that a coral that is exposed to slightly elevated ocean acidity can acclimatize to those conditions, thereby enhancing the coral’s adaptability.

“The results show the potential conditions of acidification that corals may experience; however, the extremity of the conditions varies based on the climate scenario that the world follows. In the best case, corals will be impacted, but it could be manageable. This is why we continue new research to examine the combined effects of stresses on corals,” said Powell. “This study is a big first step to examine the totality of changes that will impact corals and other marine organisms and how it varies around the islands.”

The research team will continue to investigate the future changes in Hawaiian waters, specifically, heat stress, locations of possible refugia (areas where corals may be more sheltered from stress) for coral reefs, and changes to Hawai‘i’s fisheries.

Link to video and sound (details below): https://spaces.hightail.com/receive/R6bEhJGE6i

VIDEO:

BROLL: (0:45)

0:00-0:45 — aerial and underwater shots of corals

SOUNDBITES:

Brian Powell, professor, UH Mānoa Department of Oceanography

(0:15)

“Hawaiʻi corals and coastal ecosystems are going to be facing unprecedented levels of ocean acidification. Now, the level at which they face depends on how much emissions are put into the atmosphere.”

(0:17)

“What are these compound effects on corals of temperature, of decreasing oxygen, of increasing acidity, and how these combined effects impact both corals, fish, etc.”

(0:12)

“If we curtail global emissions, then the corals will be fine. But if we continue and increase our emissions, then the corals are going to be in extreme danger.”

VOSOT SCRIPT

INTRO:

Oceans around Hawai‘i are on track to become more acidic than ever before…and that’s bad news for coral reefs.

VO:

A new University of Hawai‘i at Mānoa study used advanced models to predict how ocean chemistry will change over the next few decades.

Even in low-emission scenarios, the acidification levels are expected to be beyond what marine life has seen in thousands of years.

But there’s hope as some corals may adapt.

Researchers say it all depends on how much carbon we continue to emit.

SOT:

Brian Powell, professor, UH Mānoa Department of Oceanography

“If we curtail global emissions, then the corals will be fine. But if we continue and increase our emissions, then the corals are going to be in extreme danger.”

VO:

Researchers say this is just the beginning.

Future studies will look at heat stress, potential coral refuges and how acidification could impact Hawai‘i’s fisheries.