Lew Young, Manager of Mai Po Marshes Nature Reserve in Hong Kong, has
written me about the poisoning of Deep Bay and is happy for me to
circulate this on the Bird Nets. He writes:
"The water quality in Deep Bay is certainly one of the worst around the
coast of Hong Kong. The Environmental Protection Department (EPD) of
the Hong Kong Government has a monthly monitoring programme at a number
of stations in the Bay, and amongst other parameters, they found the
amount of dissolved oxygen (D0) in the water has been declining since
1988. In the summer of 1996, the DO levels even dropped to zero on one
of the monitoring occasions. Deep Bay was practically dead during this
time. In 1996, the density of the crabs and mudskippers that used to be
commonly found on the Deep Bay mudflat also crashed and as these are the
food for many of the migratory birds that use Deep Bay, there was
concern that the decline in food would have a knock on effect on the
birds. However, the number of waterbirds that arrived in Deep Bay
during the 1996/97 winter was about the same as that of the previous
winter (around 68,000), and so the effect does not seem to have reached
the birds yet. However, Deep Bay may be on the brink of a serious crash
if the pollution gets much worse.
Where is all the pollutants coming from? Over the past decades, there
has been a history of pig farming in the catchment around Deep Bay,
especially on the Hong Kong side. The slurry each morning would be
washed into the streams which then flows into the Bay. To control this
problem, the Government has passed a Livestock Waste Control Ordinance
and are trying to control the problem (through EPD) by requiring all
livestock farmers (e.g. pigs, chickens and pigeons) to collect all the
slurry and to treat it, rather than washing it into the streams. This
appears to be working slowly but the streams have had years of waste
thrown into them, so it will take a long time for all this to be washed
out.
Over the past 10 years however, development in neighbouring Shenzhen (on
the northern shore of Deep Bay) has been increasing, and it appears that
the speed at which sewage treatment plants are being built is lagging
behind that at which the housing estates are being built. At present,
only an estimated 50% of the waste water from Shenzhen is treated before
it enters Deep Bay. The source of the pollution into Deep Bay has now
shifted from Hong Kong to Shenzhen. Luckily, the main source of
pollution into Deep Bay is organic rather than chemical or metals, and
can be solved by more treatment facilities.
The HK Government is taking the problem of pollution in Deep Bay
seriously and EPD has recently completed a cross-border consultancy
study on the problems and how to control it. The results have not been
published yet but it is a step in the right direction.
In 1997, Hong Kong has had one of the wettest years on record and so the
large volume of fresh (rain) water coming down the rivers into Deep Bay
has flushed out and also diluted much of the pollutants. The numbers of
crabs and mudskippers on the mudflat is higher than last year but is
still low. We now wait until next year to see what the situation is
like."
***************
Bevan Craddock
Penkridge, Stafford, UK
Join WWF HK now! For more information about the work of WWF HK, visit
their Web site at http://www.wwf.org.hk
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