Making Marine Eco-systems and Seafood Safer
Variations in water temperature and salinity levels affect the toxicity levels of these chemicals and the damage they can do to marine life.
We know that air temperatures differ in different regions of the world, but we often neglect to consider the differences in water temperatures and salinity levels in our seas and oceans. Those differences matter immensely when it comes to protecting marine environments, because metals and other chemicals in the water that are damaging to both marine life and the people who consume them behave very differently in different water temperatures and saline conditions. Now, a new empirical model for testing waters has been developed by Professor Kenneth Leung of the School of Biological Sciences working with the Chinese Research Academy of Environmental Sciences. The new model will help governments set appropriate site-specific limits on discharges to safeguard marine environments and protect public health.
Chemicals get into the water in many ways, including through the paints used on ships’ hulls, whose ingredients are often toxic to micro algae. That can lead to damaged marine eco-systems and contaminated seafood that can make people sick. Triphenyltin or TPT, a toxic component of the organotin family that is commonly found in hull paint, has been found to have contaminated fishes in Hong Kong waters.
Variations in water temperature and salinity levels affect the toxicity levels of these chemicals and the damage they can do to marine life. In general, toxicity levels increase as temperatures rise, so it follows that warmer waters – such as those in Hong Kong – could see more damage to marine life compared to colder waters. Yet countries set standards for discharges without regard to these important variations.
“Current international practice seldom considers this,” said Professor Leung.
All living creatures perform best in a set optimum temperature range – for humans, it’s 22-26 degrees Celsius – and Professor Leung set about finding the optimum range for marine life. The aim was to improve regulatory systems governing chemical use around the world. In contrast to existing international practices which only tested single species in fixed laboratory conditions and with a single chemical, he gathered data from around the world and in his lab and carried out many studies and tests on different species. To protect the entire marine ecosystem, he needed to find a way to protect the weakest species of marine life. “If you protect the weakest, you can protect them all,” he explained.
The detailed research took on global implications and evolved to predict toxicity in any part of the world at any time of the year.
Professor Leung’s findings were sent to the Environmental Protection Department of the Hong Kong government, which can use the model to set more effective Water Quality Objective targets to better protect Hong Kong’s marine environment and public health.