Leung’s passion for marine science and conservation
Published on 14 Dec 2020

Professor Kenneth Leung Mei-yee (Croucher Foundation Fellowship 2000) is passionate about extending his research beyond the laboratory in order to protect the aquatic environment and come up with practical solutions to conserve biodiversity.

The Chair Professor of Environmental Toxicology and Chemistry at Department of Chemistry and the Director of State Key Laboratory of Marine Pollution, City University of Hong Kong (CityU), is one of the most eminent marine scientists in Asia, with more than 210 published papers since 1999.

In 2018, Leung was selected by Asian Scientist Magazine as one of the 100 Asian scientists representing the best of the region’s scientific community at large.

“When I was young, I loved the natural environment. My father worked for the Marine Department and I went on many trips with him. I loved the ocean. This remains my anchor point,” he said.

His training in environmental science started not at a prestigious international university but at a local technical institute in Hong Kong, where he was engaged in projects requiring accurate data and practical problem solving.

“Since my training at the technical institute I have always liked to find solutions to real-life problems. But, of course, we need the scientific theory to improve the accuracy of prediction,” he said.

He progressed to a BSc degree in Applied Environmental Sciences with first class honours from the University of Portsmouth, UK, in 1993. In 1996 his MPhil studies in Environmental Science at City University of Hong Kong took him back to the sea.

“I did an MPhil looking at pollution from fish farming, which was a big problem back then. I worked out the nitrogen budget for fish farms,” Leung said. He discovered about 70% of nitrogen inputs to local fish farms subsequently became marine pollutants and more than 30% of this was due to food wastage. He found that because different fish species had different feeding habits, much of the food was falling to the seabed.

“We designed a revised feeding protocol using floating food pellets that massively reduced pollution,” he said. This enabled him to calculate acceptable fish stocking areas for any given fish culture zone in Hong Kong and devise an approach that could reduce the algal blooms that resulted from excess nitrogen and endangered fish stocks.

Leung obtained his PhD in Marine Ecotoxicology in 2000 at the University of Glasgow, Scotland, and was subsequently awarded a Croucher Foundation Fellowship, enabling him to conduct his 18-month postdoctoral study in ecological risk assessment of chemical contaminants at Royal Holloway, University of London. During this period, he started to think if zero discharge of pollutants was impossible, how much could safely be discharged and whether this threshold could be established for each pollutant and each species of marine organism.

Previous studies had been based on fixed conditions of pH value, temperature and salinity within laboratory conditions, he said. “But the real-life environment is highly dynamic, affected by rainfall, seasonal temperature variation, and location.” For example, estuarine and non-estuarine locations also made a difference.

Leung was fascinated by the question of whether these pollution thresholds changed with the in-situ environmental conditions, and if they could be predicted using empirical models. This required extensive experimental work as different organisms respond differently to chemical pollutants, under variable environmental conditions. After some 10 years of research, his team published the model in 2018, using temperature and salinity as variables to describe how these variables influence the toxicity of metal pollutants (copper, nickel, cadmium, iron, lead, mercury and zinc) towards marine organisms.

Leung illustrates the model with a simple graph, showing the percentage of species affected in proportion to the concentration of each pollutant. The curve shifts depending on temperature or salinity. Though the research is on-going, he has already developed a more dynamic site-specific model for water quality objectives. It could also be adopted by developing nations that do not have the resources to undertake their own research, informing their water quality policies.

Leung is widely recognised as an international expert in water quality. From 2009 to 2013 he advised the Hong Kong government in its review of marine water quality objectives.

He received a Collaborative Research Fund grant of HK$7.3 million from Hong Kong’s Research Grants Council to determine the environmental impact of the ban on trawling in Hong Kong waters from 31 December 2012. The results have not yet been published but Leung revealed that the data shows biodiversity and abundance of benthic infauna (the worms, clams and mantis shrimps that live in sediments) have significantly increased since the ban.

Such a recovery was triggered by the reduction of frequent disturbance of sediment, decreasing suspended solids. Fine particulates are again settling on the seabed where they are essential foods for benthic feeders. Sessile organisms, such as oysters and mussels, are also returning.

“This is fantastic news and it’s happening all over Hong Kong, except for a few isolated pollution hotspots,” he said. However, he warned that the recovery of fish and crustaceans, while encouraging, had been more complicated, with several regional variations.

Leung has recently initiated an ecological restoration project to deploy bivalves (such as oysters and mussels) to Tolo Harbour. Bivalves filter feed and remove the microalgae and suspended organic matter in the water column and hence, eventually, reduce the organic material to be settled on the sea bottom, a contributory factor in the annual occurrence of hypoxia. The project was inspired by the so-called “Billion Oyster Project”, pioneered in New York Harbour.

Leung is leading another major marine environmental research project, in partnership with government departments, that he hopes will make a significant contribution to conserving and regenerating local biodiversity. Eco-shorelines are manmade habitats, incorporated with ecological concepts and possess diverse eco-friendly microhabitats that can be readily occupied and used by marine organisms as refuges and feeding grounds. They serve dual roles as coastal defence and functional ecosystem for boosting marine organisms by offering a much more sustainable habitat than the smooth concrete sea walls ubiquitous in Hong Kong and many other coastal cities.

The eco-shorelines research is part of a multinational collaborative initiative, devised by the World Harbour Project. Leung is a member. Recent trials showed that the abundance of inter-tidal animal species on these eco-friendly tiles increased from six to 12 compared with traditional concrete sea walls. This is broadly comparable to the number of species found on natural rocky shorelines, though, to date, the species have varied.

While impossible to replicate natural coastlines that have taken millions of years to adapt, Leung believes this technology could be an important tool for increasing marine biodiversity if retro-fitted to existing sea walls or used as mitigation in land reclamation projects.

Not all of Leung’s projects are quite so applied. He is also the project coordinator for a recent HK$3.8 million Collaborative Research Fund award (plus the same amount matched by the University of Hong Kong) to establish Asia’s premier stable isotope ratio mass spectrometry (SIRMS) laboratory in Hong Kong. Three machines will be installed and available to all of the city’s universities.

“These new machines will allow us to fingerprint anything, such as the diet of animals. They can be a conservation forensic tool, determining wild or captivity bred animals, and their origins,” he said. They could also be used for sampling human breath for diagnosis of gastrointestinal diseases.

However, he is unlikely to be confined to a laboratory for long. “Some years ago a teacher asked my young daughter what her father was very good at and she replied that I was good at making PowerPoint slides on a computer,” he said. That prompted his decision to change his approach to science. “For me, writing papers is not enough. I want to be a changer and be able to translate our research into application for improving the environment,” he said, explaining his motivation for retaining such an interest in applied science.

Professor Kenneth Leung Mei-yee was educated in Hong Kong and first studied Environmental Science at a local technical institute. He received a BSc degree in Applied Environmental Sciences with first class honours from the University of Portsmouth, England, in 1993, and his MPhil in Environmental Science at City University of Hong Kong in 1996. After gaining a Swire Group James Henry Scott PhD Scholarship, he studied at the University of Glasgow, Scotland, earning his PhD in Marine Ecotoxicology in 2000. He was subsequently awarded a Croucher Foundation Fellowship, enabling him to conduct postdoctoral studies in ecological risk assessment of chemical contaminants, at Royal Holloway, University of London in 2000-2001. He joined the University of Hong Kong as Research Assistant Professor in 2002, rising to Professor in 2013. In 2017, he was awarded the prestigious 19th Biwako Prize for Ecology from the Ecological Society of Japan for his outstanding academic achievements and societal contributions in Asia. In 2017, he was made a Fellow of the Society of Environmental Toxicology and Chemistry (SETAC) and, in 2018, he was named one of the 100 Asian Scientists who represent the best of Asia’s scientific community at large by Asian Scientist Magazine. He was also appointed a Justice of the Peace by the Hong Kong SAR Government in 2018. In August 2020, he returned to his alma mater, City University of Hong Kong to serve as Chair Professor at Department of Chemistry and Director of State Key Laboratory of Marine Pollution. Professor Leung received a Croucher Fellowship in 2000.

Extended Reading:

  1. Prof Leung’s personal page in Croucher Foundation: https://scholars.croucher.org.hk/scholars/kenneth-leung
  2. Prof Leung’s personal page in City University of Hong Kong: https://www.aquatictox.com/
  3. The news of Prof Leung being selected by Asian Scientist Magazine as one of the 100 Asian scientists: https://www.asianscientist.com/2018/03/pr/recognizing-excellence-asian-scientist-100-2018/