Scientists discover how microplastics accumulate in coral reefs

Coral reefs, often called the rainforests of the sea, are among the most diverse and essential ecosystems on Earth. These underwater structures provide shelter, food, and breeding grounds for countless marine species. However, microplastics have become a growing threat, infiltrating these habitats and harming marine life.

Coral reefs help maintain ocean health by filtering water, generating oxygen, and protecting coastlines from storm damage, but microplastics disrupt these crucial functions. Understanding how microplastics interact with coral reefs is a key step in protecting these vital habitats.

How corals trap microplastics

A research team from the University of Waterloo has made a significant discovery regarding microplastic accumulation in coral reefs. They found that mucus secreted by coral naturally attracts and traps microplastics. This insight could help scientists develop strategies to protect coral reefs from plastic contamination.

The study, conducted by researchers from the Faculty of Engineering, applied advanced nanotechnology to examine how microplastics interact with coral surfaces. Their findings reveal that the sticky mucus surrounding corals plays a major role in capturing and holding microplastics in place.

“This discovery is critical because it helps us understand how microplastics attach to coral ecosystems, which is vital for developing effective removal strategies,” said Dr. Boxin Zhao, a professor in the Department of Chemical Engineering and a member of the Waterloo Institute for Nanotechnology.

Why coral reefs matter

Coral reefs support nearly a quarter of all marine species. They serve as nurseries for fish populations, sustain coastal communities, and contribute to global biodiversity.

Many economies rely on reefs for tourism and fishing, making their protection essential for both environmental and economic reasons.

In addition to sustaining marine life, coral reefs help regulate ocean chemistry. They remove carbon dioxide from the water, reducing ocean acidification and supporting broader climate stability. Their role in protecting shorelines is equally vital, as they act as natural barriers against waves, storms, and erosion.

With so many benefits linked to healthy coral reefs, the rise of microplastic pollution adds another layer of urgency to conservation efforts. Understanding how plastics accumulate in these ecosystems is an important step toward mitigating damage and ensuring long-term survival.

Coral mucus and microplastics

The University of Waterloo researchers approached this issue from a materials science perspective. They used nanotechnology to analyze the interaction between coral mucus and microplastics at a microscopic level.

In a controlled laboratory setting, they recreated the environmental conditions of a real coral reef. They then conducted mechanical adhesion tests on both living corals and synthetic reef structures.

The goal was to measure contact forces and determine what causes microplastics to stick to coral surfaces. The results confirmed that mucus secreted by coral plays a central role in capturing these tiny pollutants.

By identifying this key factor, scientists now have a clearer picture of how microplastics become embedded in coral ecosystems. This knowledge paves the way for developing practical solutions to remove these pollutants without causing further harm.

Removing microplastics from coral reefs

With this newfound understanding, researchers are now shifting their focus toward developing innovative cleanup methods. Any effective solution must not only remove microplastics from reefs but also prevent them from drifting back into the ocean.

One promising idea involves designing artificial coral structures that could act as plastic traps. These structures would collect pollutants before they reach natural reefs, reducing the burden on existing ecosystems.

“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 Dr. Sushanta Mitra, executive director of the Waterloo Institute for Nanotechnology.

Coral biology and environmental pollution

The research team’s findings mark an important step in tackling microplastic pollution in coral reefs.

Their work highlights the complex relationship between coral biology and environmental pollution. While more research is needed, this discovery offers hope for creating targeted solutions that reduce microplastic buildup in marine environments.

The next challenge lies in translating these insights into large-scale applications. Conservationists, scientists, and policymakers must work together to develop strategies that not only remove existing pollutants but also prevent new plastic waste from entering the ocean.

Addressing plastic pollution at its source – by improving waste management systems and reducing single-use plastics – remains critical to long-term success.

The study, which included Dr. A. Reum Kim, a postdoctoral fellow at Waterloo, was recently published in ACS ES&T Water.

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