Breakthrough study uncovers how microplastics stick to coral reefs
Climate change is devastating the world’s coral reefs, and pollution from microplastics in the oceans further damages these delicate ecosystems. Researchers at the University of Waterloo have made a breakthrough in understanding how and why microplastics get trapped in coral reefs. The new study sheds light on the role of mucus naturally secreted by coral reefs in the accumulation of microplastic pollution.
Removal strategies must ensure that detaching microplastics does not worsen environmental impact by floating back into the ocean water. Designing artificial coral reefs to capture microplastics may be the most promising answer in the race to save the planet’s coral reefs.
Coral reefs are diverse and important ecosystems, providing habitat for 25 percent of all marine life. They provide food, shelter, breeding grounds, and nurseries for millions of species. Coral reefs play a role in filtering water and creating oxygen. They also protect shorelines from the impact of storms and floods.
Other studies have examined microplastics settling on branches within coral reefs and the accumulation of microplastics in downstream regions that form a “sink” for microplastic pollution.
“We are the first group to quantify the mechanism of microplastic trapping on coral reefs via its mucus layer by directly measuring adhesion between mucus and microplastics,” said Boxin Zhao, a professor in the Department of Chemical Engineering. “This discovery is critical because it helps us understand how microplastics are trapped in coral ecosystems, which is vital for developing effective removal strategies."
The study conducted by Zhao, a University of Waterloo Endowed Chair in Nanotechnology, Dr. Sushanta Mitra, a professor in the Department of Mechanical & Mechatronics Engineering and the Executive Director of the Waterloo Institute for Nanotechnology, and Postdoctoral Researcher A-Reum Kim, represents a new perspective in material science by using nanotechnology to look at the interface between coral reefs and microplastics.
Using a unique experimental set-up (see left), researchers created an environment in the lab that mimics conditions on a real coral reef. They conducted tests on a synthetic coral reef and a real coral reef in the lab. Their finding is that the mucus naturally secreted by coral reefs has strong adhesion characteristics, so microplastics that are floating around in the ocean become stuck to the coral reef.
Using a mechanical test, researchers measured the contact of force between microplastics and the coral reef. The research group applied adhesion tests on both the real and synthetic coral reefs.
"By understanding the forces involved in microplastic adhesion, we can design solutions that not only prevent further harm but also mitigate further microplastic pollution in coral reefs," said Mitra.
The next step for the research group is to use the insight to design microplastic cleanup technologies that can capture microplastics in the marine environment and protect marine life.
The study recently appeared in the ACS ES&T Water journal.