A Study on the Effect of Biofilter Deployment on the Water Quality, Sediment and Benthic Community at Lo Tik Wan Fish Culture Zone

The objective of the research is to assess the water quality, sediment component, and benthic communities of Lo Tik Wan Fish Culture Zone (FCZ) before and after the deployment of filters.Environmental impacts of marine fish farming have been well documented, especially those of salmonid farming in temperate regions. These studies clearly demonstrated the pollution effects on water quality and sediments due to the release of organic and inorganic wastes, therapeutic chemicals or antifoulants, and physical obstruction and modification of water movement and sedimentation.The deployment of artificial reefs on muddy or soft bottom is used to enhance habitat heterogeneity and improve the benthic environment. Apart from providing sanctuaries for schools of fish, including spawning adults and growing juveniles, the reefs also act as additional substrates for the colonization of benthic organisms, which can serve as a major food source for many fish species. More importantly, most of these benthic sessile organisms are filter feeders, which rely on the nutrients and associated phyto- and zooplankton as their food supply. A recent study undertaken by CityU demonstrated the efficiency of such biofiltration capacity of artificial reefs deployed at the Kau Sai Wan FCZ, especially on the benthic communities near the culture area. The current study will further ascertain the effectiveness of artificial reefs as biofilters and generate data to guide future deployments of artificial reefs at other FCZs in local waters.