Table 7.2a Ecological Value of River Habitats in the
Assessment Area.
|
Criteria |
Rivers |
|
Naturalness |
Although they remain largely
natural, river habitats in the Assessment Area have been variously modified,
and receive moderate inputs of domestic sewage and agricultural run-off. |
|
Size |
PNH, TTT and LTT Rivers:
Moderate. LTT (2) River: Small
(approximately 1-2m in width). |
|
Diversity |
Moderately diverse fish
communities. |
|
Rarity |
The estuarine confluence
and lower reaches of the rivers supported several avifaunal species of
conservation interest, comprising: Grey Heron (Ardea cinerea), Great Egret (Casmerodius alba),
Little Egret (Egretta garzetta),
Chinese Pond Heron (Ardeola bacchus), Striated Heron
(Butorides striatus),
Black-crowned Night Heron (Nycticorax nycticorax) and White-throated Kingfisher (Halcyon
smyrnensis).
PNH River: Supported fish species of
conservation interest: Flagtail (Kuhlia marginata) & Predaceous
Chub (Parazacco spilurus). One avifaunal species of conservation
interest recorded: Plumbeous Redstart (Rhyacornis fulignosus). TTT River: Supported fish species of
conservation interest: Predaceous Chub (Parazacco
spilurus). LTT & LTT (2) Rivers: Supported the avifaunal species of conservation interest
recorded: Common Teal (Anas crecca) Relatively unmodified
lowland rivers are becoming increasingly rare habitats in Hong Kong. |
|
Recreatability |
Moderate. |
|
Fragmentation |
The habitats are generally
unfragmented, although agricultural weirs (such as in PNH River) could
prevent the migration of fish between downstream and upstream reaches of the
rivers. |
|
Ecological
linkage |
The rivers (especially LTT
& LTT (2)) are structurally and functionally linked to areas of marshland
in the Assessment Area. PNH River flows close to woodland at Butterfly Hill,
and is functionally linked to this habitat. |
|
Potential value |
With the removal of
pollution sources and restoration of river-beds and banks, the ecological
value of all rivers could be improved. |
|
Nursery ground |
The lower, estuarine
reaches of the rivers appear to serve as a nursery and breeding ground for
some common brackish fish species. |
|
Age |
N/a |
|
Abundance/Richness of Wildlife |
Moderate. |
|
Ecological value |
PNH River: Moderate-high TTT River: Moderate LTT River: Moderate LTT (2) River: Low-Moderate |