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The Agriculture, Fisheries and Conservation Department deployed 10 artificial reefs late last month (March) at the Sham Wan Fish Culture Zone to serve as biofilters to improve water quality.
A department spokesman said similar biofilters deployed at the Kau Sai Fish Culture Zone in 2002 had proved successful in improving the marine environment underneath and surrounding waters.
"Fish faeces or unconsumed feed from fish culture activities can lead to an increase in water turbidity. In some cases this organic matter accumulates in the bottom mud, increasing the possibility of bottom oxygen depletion," he said.
"The specially designed biofilters have a high surface area to volume ratio and provide hard surfaces for development of numerous filter feeding organisms. These organisms will then filter and remove nutrients and suspended particles in the water."
It is estimated that the 10 biofilters can filter 6,000 cubic metres sea water per day at the Sham Wan Fish Culture Zone.
"Biofilters can also enhance marine life by providing shelter. Fish and marine life attracted to the biofilters can help consume excess feed falling through the cage nets, reducing pollution in the fish culture zones," the spokesman added.
Scientific research in Russia, Poland and Israel also indicated the effectiveness of artificial reefs as biofilters.
Ends/Tuesday, April 3, 2007
Issued at HKT 15:21
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