Ocean acidification is destroying coral reefs. Here's how 2 scientists are using bone research to protect them against climate change.

• The ocean stores a huge amount of carbon, but excessive human emissions are changing its chemistry.
• It's becoming more acidic — hitting marine ecosystems and causing coral reefs to crumble.
• Two scientists based in Scotland are taking inspiration from bone research to help protect the reefs.
• This article is part of "Gains in Green Tech," a series showcasing some of the most transformative solutions to the climate crisis. For more climate-action news, visit Insider's One Planet hub. 

The remote fishing village of St Abbs, Scotland, was made famous as the filming location of New Asgard in Marvel's "Avengers" movies.

But to locals, it's better known as a surfing and walking destination thanks to its sandy beaches and 200-acre nature reserve.

St Abbs is also home to a marine-research facility where scientists tackle an array of issues facing the ocean, with a focus on conservation.

Inside one of the facility's labs are 40 small "future oceans" — tanks of seawater chemically altered to reflect potential future scenarios of the ocean impacted by climate change. 

The ocean has absorbed around 30% of the carbon dioxide produced since the industrial revolution, making it an invaluable tool in the fight against climate change.

But all this CO2 is changing the ocean's chemistry, making it more acidic. Increased acidity could devastate marine ecosystems, which are built upon coral reefs, and in turn, affect the fish and seafood humans eat. 

The tanks, which hold dead and alive deep-sea coral, are part of a research project by the marine biologist Sebastian Hennige and Uwe Wolfram, a material scientist who focuses on bones.

The pair met in 2016 while working at Heriot-Watt University in Scotland. Hennige had been researching deep-sea corals and their breaking points when he spotted Wolfram, a new hire who worked on osteoporosis in humans, on the university's faculty page. 

Osteoporosis is a disease in which bones weaken and become more likely to break. Wolfram compared bones with osteoporosis to Swiss cheese with holes. 

Hennige, who is now at the University of Edinburgh, initially wanted to know if Wolfram's expertise in how bones break down could be applied to coral dissolution.

The pair met over coffee and Hennige brought a piece of coral with him. They found clear overlap between bones and coral, and that initial conversation kick-started years of ongoing collaboration. 

It's "mind-boggling business" how similar porosity in corals, known as coralporosis, and osteoporosis are, Wolfram said. 

Reefs are built upon dead corals, or coral skeletons, which are made of calcium carbonate and support the whole reef ecosystem. As the ocean becomes more acidic, the dead coral skeleton is eaten away by seawater, becoming weaker, more brittle, and at risk of fracturing — just like bones affected by osteoporosis. Living coral also has a protective layer of "skin."

"This can start to make changes to habitats on a very, very large scale," Hennige said. As the base becomes weaker, it may crumble over time, become less complex, and not be able to support as much marine life.

Hennige said that an increased understanding of the effects of ocean acidification will make it easier to protect reefs from "additional stresses," such as by restricting some fishing around at-risk or particularly well-connected reefs, which spread larvae and help populate others.

Hennige also said there's a large data gap about the ecosystem at the bottom of the ocean and that there are a lot of poorly mapped coral reefs. One of the main challenges, he said, is that the ocean is "deep, it's dark, it's expensive to get down there."

Small changes have a big impact 

In the dark, cold lab at the St Abbs Marine Station, Hennige and Wolfram mimic deep-sea conditions — temperatures are capped at 9 degrees Celsius and light is limited. 

"We're trying to use these tanks as a kind of crystal ball, to look into what a future ocean may look like," Hennige said. Ocean acidification is the main focus, but the ocean isn't facing just one threat — some tanks have multiple stressors, such as deoxygenation and increased temperatures, in an attempt to provide realistic future scenarios.

The ocean's pH stood at 8.2 before the industrial revolution; today it's 8.1, which is the experiment's control tank level. The tanks range from this to pH 7.7, on a scale of 1 to 14, with 1 being acidic and 14 being basic, or alkaline. 

This sounds like a small change, but it's a big deal for lots of marine organisms, Hennige said, particularly to calcifying organisms, such as various types of algae, crustaceans, and corals. That's because as the ocean gets more acidic, there are fewer carbonate ions available in the water to make calcium carbonate. Corals are made of calcium carbonate, as are shells. 

In the lab, the researchers typically don a jacket and hat because of the cold, while Hennige will sometimes go in with a red-light head torch to avoid turning the light on. Researchers add precise amounts of carbon dioxide and nitrogen, which are used to ramp up acidification and bring down the oxygen level, respectively. 

The research began in January and will run for one year, with data collected in monthly intervals to help understand coral responses to ocean acidification and timescales. The pair are taking advantage of medical technology like X-rays and CT scans to monitor coral-dissolution rates.

Predicting the health of coral reefs

The end goal is to create a computer model to predict the health of reefs by combining the research with data from a "whole wagonload" of historic corals, marine biology, and climate data, Wolfram said. This could ultimately help to conserve reefs by discovering which water conditions are the most critical and how long coral survives in such conditions, he added.

Such a model could be very powerful if it points to reefs that must be protected, according to Jason Hall-Spencer, a marine biology professor at Plymouth University in the UK.

"The focus should really be on how to quickly and effectively remove damaging practices — things that we know are very likely to kill off corals," Hall-Spencer said. That's not just ocean acidification, but carbon-dioxide emissions, deforestation near coral reefs, and fishing practices like trawling, he said.

Hennige and Wolfram are leaning on advances in the medical field. Research on the disease has created "wonderful models" that flag when a person is at risk of osteoporosis by looking at factors including lifestyle and genetics, Hennige said. "That's what we want to be able to do for these corals," he added. 

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