CSRI researchers study ancient corals to understand ocean acidity

Kira Fish ’19 and William Harmon Norton Professor of Geology Rhawn Denniston explored ancient, fossilized coral samples for the Cornell Summer Research Institute.

“We want to find really well-preserved corals, so we can analyze isotopes inside them–Boron isotopes, which will hopefully help us analyze ocean pH about a couple million years ago,” Fish said.

“The contribution that we hope to make is to understand how corals can be used, ancient corals can be used, to understand pH changes,” Denniston added.

Finding the coral samples, however, was tough. The pair traveled to Costa Rica this summer to find and collect coral fossils, using geologic maps to pinpoint their field research locations.

“It’s only under extremely unusual circumstances that we find ancient corals that haven’t been altered,” Denniston said. “One of the things that we were doing is looking for these–a needle in the haystack. We go around looking at coral after coral, outcrop after outcrop. We hope to find that one sample, maybe just part of one sample that appears not to have been altered since it was alive.”

“We analyzed them with hand lenses to make sure they were, at least visually, they were pristine enough because you can see if they’ve been completely altered,” Fish said.

They shipped back 10 samples, which went through a variety of lab tests to ensure they were viable samples. This team is anxious to learn more because many people are concerned about changes in the oceans. 

“About 50 percent of the C02 that we have emitted since the industrial revolution has gone into the ocean,” Denniston said. “When it goes into the ocean, it reacts with the water and forms an acid, called carbonic acid. That acid makes it harder for things like corals to live. So, the coral reefs around the world [and] the little plankton that make up the base of a lot of the marine food chain, those things are made of calcium carbonate, of materials that dissolve in acid. The more acidified the ocean gets, the harder it is going to be for corals and those little organisms to survive.”

Fish said not many people have done research on fossilized coral this old. She’s fascinated by the topic and is excited to see the results of the research and where this opportunity will take her in the future. 

“I think it was really cool to experience being in the field and what that would be like,” Fish said. “I really felt like part of a team of these people who were actually working to do something and sort of got an insight to maybe what the rest of my life would look like, if I choose this to be my career.”

To learn more about other CSRI projects, visit cornellcollege.edu/research.