Plight of Lam Tsuen River

PUBLISHED : Friday, 10 December, 1993, 12:00am
UPDATED : Friday, 10 December, 1993, 12:00am

IN early 1991 I wrote to these columns, expressing concern over the ecological effects of road-widening works in the Lam Tsuen River Valley.

Specifically, destruction of the river banks and bed was caused by bulldozers and excavators operating within the river itself, with the result that the habitat was degraded and downstream sections were polluted by large quantities of fine sediment whichblanketed the river bed.

Following my letter, a reply from a representative of the Highway Department was published, which contained an assurance that contractors would be requested to take every care to minimise damage to the habitat, etc, etc.

I have been carrying out research in the Lam Tsuen River for some years, and so have been able to document the ecological degradation resulting from the sediment pollution including a decline in species diversity and animal abundance.

As the roadworks near completion, I have been able to monitor recovery of the impacted section on a month-to-month basis by comparing it with an unimpacted part of the river upstream of the roadworks.

The damaged river bed has now been replaced by a concrete culvert, thereby reducing habitat diversity and the ecological value of that area, but sections downstream of the work have been showing signs of recovery of animal diversity.

All that changed last week when employees of the contractor responsible for the roadworks drove an excavator into the river opposite the Kadoorie farm (upstream of my ''unimpacted'' study site), dug out the stream bed and tore up the banks.

So much for assurance of minimal environmental damage.

The consequences of this act of environmental vandalism include abortion of my own research, and destruction of the communities of insects and fishes which live in the impacted area.

While these creatures fascinate me, I recognise that they may be of only minor concern to most readers of your column.

Of greater significance is the fact that the impacted section of the Lam Tsuen River is a breeding site of the Hong Kong Newt, Paramesotriton hongkongensis, which occurs nowhere else in the world but Hong Kong.

As this species is protected by law under the Wild Animals Protection Ordinance, the fact that - yet again - the Lam Tsuen River has been subjected to the depredations of heavy machinery does not give me much confidence in the ability of the Government to protect what is left of our rapidly-dwindling countryside.

Dr DAVID DUDGEON Reader Department of Zoology The University of Hong Kong