How corals can actually benefit from climate change effects

November 5, 2014, Northeastern University
Justin Ries, an associate professor at the Marine Science Center, researches biogeochemical oceanic change over long time periods. Credit: Brooks Canaday/Northeastern University

Researchers from Northeastern University's Marine Science Center and the University of North Carolina at Chapel Hill have found that moderate ocean acidification and warming can actually enhance the growth rate of one reef-building coral species. Only under extreme acidification and thermal conditions did calcification decline.

Their work, which was published Wednesday in the journal Proceedings of the Royal Society B: Biological Sciences, is the first to show that some corals may benefit from moderate ocean .

Justin Ries, an associate professor at Northeastern and one of the paper's co-authors, focuses his research on the biological impacts of rising atmospheric levels, which has been increasing ocean acidity since the Industrial Revolution. One group of organisms that would be greatly affected by ocean acidification are those that build calcium carbonate shells and skeletons, such as , snails, and clams, which, he said, are already near the point of dissolving in some parts of the ocean.

The authors attribute the coral's positive response to moderately elevated carbon dioxide to the fertilization of photosynthesis within the coral's algal symbionts, which may provide the coral with more energy for calcification even though the seawater is more acidic. They propose that the eventual decline in coral calcification at the very high levels of carbon dioxide occurs when the beneficial effects of fertilizing photosynthesis are outweighed by the negative effects of acidification on the skeleton-forming process.

"The study showed that this species of coral (Siderastrea siderea) exhibited a peaked or parabolic response to both warming and acidification, that is, moderate acidification and warming actually enhanced coral calcification, with only extreme warming and acidification negatively impacting the corals," Ries said. "This was surprising given that most studies have shown that corals exhibit a more negative response to even moderate acidification."

Furthermore, their work indicates that ocean warming is likely to threaten this coral species more than acidification by the end of the century, based on projections from the Intergovernmental Panel on Climate Change.

He noted that in the past 200 years, ocean pH level has dropped from 8.2 to 8.1 and is expected to fall even further to about 7.8 over the next one or two centuries. That is a significant decrease over a relatively short period of time, Ries said, when looking at the geologic history of ocean acidification.

"The amount of change that would typically occur in about 10 million years is being condensed into a 300-year period," Ries said. "It's not the just the magnitude of the change that matters to the organisms, but how quickly it is occurring."

In addition to publishing these findings, Ries has leveraged his research in this area to secure a prestigious fellowship from the Hanse Wissenschaftskolleg Institute for Advanced Study in Delmenhorst, Germany and a supporting research award from the National Science Foundation. He will spend 10 months over the next four years there working with researchers at three prominent German research institutions to use various tools such as microelectrodes, isotope ratios, and pH sensitive dyes to see how affects the organisms' internal calcifying processes that lead to the formation of their shells and skeletons.

"Acidification of the surrounding seawater is certainly important for marine organisms, but what is equally as important—perhaps even more important—is how the chemistry of their internal calcifying fluid responds to these changes in seawater chemistry," Ries said.

Explore further: Coral growth rate plummets in 30-year comparison

More information: The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming, rspb.royalsocietypublishing.or … nt/281/1797/20141856

Related Stories

Coral growth rate plummets in 30-year comparison

September 17, 2014

A team of researchers working on a Carnegie expedition in Australia's Great Barrier Reef has documented that coral growth rates have plummeted 40% since the mid-1970s. The scientists suggest that ocean acidification may be ...

Ocean acidification could lead to collapse of coral reefs

September 29, 2014

An expedition from the Hebrew University of Jerusalem and the Carnegie Institute of Science has measured a roughly 40% reduction in the rate of calcium carbonate deposited in Australia's Great Barrier Reef in the last 35 ...

Scientists sound alarm over ocean acidification

October 8, 2014

Ocean acidification has risen by a quarter since pre-industrial times as a result of rising carbon emissions, casting a shadow over the seas as a future source of food, scientists warned on Wednesday.

Recommended for you

Scientists shed light on biological roots of individuality

February 16, 2018

Put 50 newborn worms in 50 separate containers, and they'll all start looking for food at roughly the same time. Like members of other species, microscopic C. elegans roundworms tend to act like other individuals their own ...

Plants are given a new family tree

February 16, 2018

A new genealogy of plant evolution, led by researchers at the University of Bristol, shows that the first plants to conquer land were a complex species, challenging long-held assumptions about plant evolution.

Birds and beans: Study shows best coffee for bird diversity

February 16, 2018

It's an age-old debate for coffee lovers. Which is better: Arabica beans with their sweeter, softer taste, or the bold, deep flavor of Robusta beans? A new study by WCS, Princeton University, and the University of Wisconsin-Madison ...

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

tadchem
3 / 5 (2) Nov 05, 2014
Often overlooked: the most abundant form of dissolved carbon in the ocean is bicarbonate ion in the pH range 6.37 to 10.36. This is the form of carbon used by corals to form their carbonate skeletons as well as the form absorbed by alga to build organic tissue.
Egleton
5 / 5 (1) Nov 05, 2014
Is my assmption corect tadchem, that you are implying that the coral can use bicarbonates with a much greater range than postulated?
It is not refered to in the passage but I should inagine that the "studies" include changing the corals environment in a tank of water and observing the empirical results.
tritace
Nov 05, 2014
This comment has been removed by a moderator.
richard_f_cronin
1 / 5 (3) Nov 28, 2014
Human CO2 induced climate change is B.S. Global Warming and the nano-increment of additional CO2 increase is entirely due to the GeoReactor. See www dot nuclearplanet dot com

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.