Science & Tech

Returning calcium to lakes and oceans, one seashell at a time

An 18-year-old environmentalist from Hamilton, Ont. is gaining recognition for her experiments using pulverized seashells to lower the acidity of ocean and lake water

  • Mar 19, 2020
  • 469 words
  • 2 minutes
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As 11-year-old Isabella O’Brien plunged into the cool blue waters of the Caribbean Sea with her scuba-diving gear, she peered around. There were beautiful spots of shimmering, vibrant coral, but also patches that were grey, dull and dying, she recalls. Usually, divers pass over these spots, looking for the most colourful parts of Gonzalo’s Reef, a popular dive spot in Akumal, Mexico. But O’Brien couldn’t ignore them.

Isabella O’Brien scuba-diving with her dad in Akumal, Mexico. (Photo courtesy Isabella O’Brien) 
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Returning calcium to Canada’s freshwater lakes 

For her second project, O’Brien tackled a similar issue on a local scale: bringing calcium back into freshwater lakes in Ontario. Using the same method as her ocean acidification project, she was able to demonstrate that pulverized shells increased calcium levels in lake water samples she collected. 

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O’Brien collecting water samples from Soyers Lake, Ont. (Photo courtesy Isabella O’Brien)

Some organizations, like the Friends of the Muskoka Watershed, have already attempted to return calcium to lakes through projects of their own. The organization launched Canada’s first residential wood ash recycling program, taking wood ash and sprinkling it in test plots in Muskoka’s maple sugar bushes. This enhances the health of both trees and lakes, according to Norman Yan, chair of Friends of the Muskoka Watershed. 

Yan acted as a scientific advisor for O’Brien’s lake calcium project three years ago, and says he holds her in very high regard. Using pulverized shells to help return calcium to lakes makes sense in the Maritime provinces, where oyster shells are readily available, he says. In Ontario, on the other hand, using wood ash to help return calcium to lakes and forests is proving effective. 

“Everything is connected,” he says. “We’ve been depleting the soils of Eastern North America by acid rain for half a century. It’s time to start behaving like gardeners and bring those nutrients back.”

Inspiring the next generation

Now a student at the University of Southern California, O’Brien says she has decided to focus her studies on environmental politics.

“I’ve found that for so many of these environmental issues like calcium decline, we have different solutions available, but we are not having them implemented in policy,” she says. 

She says she hopes to be able to inspire youth to also take action on environmental issues that are important to them. O’Brien recalls a time a girl came up to her, saying she was so inspired by her science fair project that she decided to conduct her own.

“That just kind of blew my mind. To have someone my own age who read about my project and then decided to also enter a science fair project is just really exciting,” O’Brien says. “I not only inspired her, but she actually took action and did her own project. That is just fantastic.”


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