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SGS helps in the conservation of Mai Po Nature
Reserve
Introduction | Results
Special Thanks to
SGS Hong Kong Laboratory.
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Introduction
Mai Po Nature Reserve forms part of the largest
wetlands in Hong Kong, occupying an area of 381 ha. The diversity of
wetland habitats at Mai Po and around inner Deep Bay are internationally
important because they serve both as a wintering and a stopping-over
site for some 100,000 migrating migratory waterbirds every year.
The traditionally operated shrimp ponds (gei
wai) at Mai Po are managed by WWF Hong Kong to maintain the cultural
value of the site, provide habitat for wildlife, particularly roosting
and feeding ground for waterbirds. For example each winter, the gei
wai are completely drained in turn to harvest the fish stock inside
the ponds. At this time, up to 1,600 wintering waterbirds, such as
herons, egrets and the endangered Black-faced Spoonbill Platalea minor,
may be attracted into a single gei wai to feed on small non-commercial
fish and shrimp in the shallow water at the bottom of the pond.
The traditional management of the Mai Po gei
wai requires that water inside the pond be exchanged with that in Deep
Bay during the spring and neap tides each month. This practice would
allow juvenile shrimp and fish larvae from the Bay to be stocked into
the pond as well as allow clean water from Deep Bay to enter the pond.
However, the declining water quality in Deep Bay due to increasing
pollution loads from the Shenzhen River and the Yuen Long / Kam Tin
catchments are now exerting a serious threat to the aquatic environment
at Mai Po and Inner Deep Bay, especially to the Mai Po gei wai.
As a result, WWF Hong Kong has a routine water
quality monitoring in Mai Po Nature Reserve, to provide early indication
of any adverse changes to the water quality in the gei wai within the
Reserve. If such changes were found, then the Reserve would quickly
implement any necessary actions to protect the Reserve and its wildlife.
Areas of particular concern include the problem
of organic pollution affecting the survival of shrimps and fish in
the gei wai and that of trace metal in the water and soil accumulating
in animals, such as fish, oysters and shrimps. In addition, WWF Hong
Kong has been creating rain-fed ponds in Mai Po to provide a freshwater
habitat for wildlife. Over the past few years, these ponds have become
a popular roosting place for many waterfowl especially during winter.
However, the droppings from many waterfowl using these ponds causes
a deterioration of the water quality of the ponds and this may eventually
affect the health of the waterfowl.
We have compared the water and sediment quality
of the gei wai and rain-fed ponds with the existing guidelines stated
in Water Quality Objectives (WQO). For the analysis work, WWF Hong
Kong would like to acknowledge SGS Hong Kong Laboratory for their kind
technical support in conducting a half-year intensive water quality
monitoring programme for the Reserve from June to December 2003.
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