Assessing impacts of microplastics on marine ecosystems and human health

Hong Kong’s unique marine environment, with its rich ecosystems, provides vital habitats and food sources for various marine species. However, rapid urbanization and population growth pose significant challenges, including marine pollution, overfishing and climate change.

A research team from the Department of Food Science and Nutrition (FSN) at The Hong Kong Polytechnic University (PolyU) is actively addressing these sustainability challenges.

Their focus is on innovative marine pollution monitoring technologies and sustainable seafood research, which includes assessing the impacts of microplastics on marine ecosystems and human health, and restoring pearl oyster reefs, in alignment with the United Nations Sustainable Development Goals 2, 3 and 14.

Monitoring of microplastics in seafood

Plastic waste is pervasive, and microplastics are easily ingested by marine life, accumulating in their bodies and affecting other levels of the food chain and so posing a major threat to marine ecosystems. According to 2023 statistics from the United Nations Food and Agriculture Organization, Hong Kong residents consume an average of 65 kilograms of seafood per person per year, which is more than three times the global average of about 20 kilograms.

Led by Dr. James Kar-Hei Fang, Associate Professor of FSN, the research team employs automated mapping techniques using Raman microspectroscopy to extract and characterize microplastics accumulated in local seafood, such as green-lipped mussels (Perna viridis).

The study revealed that each gram of fresh mussel meat contained 0.2 to 1.8 items of microplastics, ranging from 40 to 1,000 micrometers in length. It is estimated that each Hong Kong resident could ingest up to 10,380 microplastics annually through consumption of bivalve shellfish, a concerning figure. The research has been published in Journal of Hazardous Materials.

To confirm the potential ingestion of microplastics by humans, the team had previously analyzed the microplastic content in Hong Kong residents’ feces. It is estimated that their intake rate of microplastics could be about five times higher than those observed in other Asian and European regions. That research was published in Toxics in 2022.

Based on these findings, the team is actively exploring the potential health consequences of microplastics on humans, and collaborating with other PolyU Departments to investigate methods such as bubble barriers and bacterial biofilms to remove microplastics from seawater.

Dr. Fang has recently received the 2024 Pew Fellowship in Marine Conservation, one of the six global awardees and the sole awarded scientist from East Asia. He stated, “Our research findings continually inspire us to develop and apply advanced technologies to explore innovative solutions and strategies to address the microplastic issue, mitigate its impacts, protect precious marine ecosystems, and ensure the sustainability of marine food sources.”

Restoration of pearl oyster reefs

Dr. Fang’s contributions to marine conservation extend to the restoration of pearl oyster reefs to improve marine environmental health and biodiversity, thereby benefiting local fishery resources. Historically, Hong Kong boasted rich pearl oyster reef ecosystems, providing habitats for other marine life and supporting a thriving pearl industry. However, over-exploitation and marine pollution have led to the degradation of pearl oyster populations, diminishing the surrounding ecosystem services.

To enhance the marine environment and biodiversity, Dr. Fang’s team has selected sites in Hong Kong’s Tolo Channel to restore pearl oyster reefs using cultured pearl oysters. They employ advanced 3D technologies to track and analyze the influences of these reefs on local biodiversity, and leverage the filter-feeding nature of pearl oysters as a biomonitoring tool to assess marine pollution and improve water quality.

The team also collaborates with local fishermen on aquaculture technology to support sustainable fisheries development. Through pearl oyster aquaculture, Dr. Fang aims to promote the econutrition concepts and revitalize the local pearl industry, benefiting both the environment and the community. His insights were published in the Voices feature in the journal One Earth.

While Hong Kong’s marine ecosystems face challenges, they also hold immense research potential and hope. Dr. Fang remarked, “Past research by scientists and scholars has provided crucial scientific evidence and technical support for marine conservation and sustainable development.

“However, marine conservation represents a prolonged and rigorous task that requires the collective efforts of governments, academia, businesses and citizens.

“Through research innovation and community education, our goal is to raise conservation awareness and inspire a sense of responsibility within the community to protect the environment, contributing to the sustainable development of Hong Kong’s ecosystems.”