The environment

Shan Pui River is one of the larger rivers in Hong Kong, yet its ecological state is inferior to other, smaller rivers, such as Lam Tsuen River and Tung Chung River. The upper course of Shan Pui River is still mainly in its natural state. The riverbed is predominantly coarse sand, with exposed bedrock and small waterfalls and pools in some locations. The lower course was channelized, and lined with concrete. This ruined the river’s ecology along the lower stretch, which passes Shap Pat Heung and Yuen Long New Town. There are estuarine mudflats, which support Hong Kong’s largest mangrove stand. As the tide falls, open mudflats are exposed



The lower course of Shan Pui River was concreted.

Upper course


In areas with gentler gradients, tiny wetlands may form over alluvial deposits. Large patches of Chinese Lipocarpha (Lipocarpha chinensis) and occasional Pitcher Plants (Nepenthes mirabilis) can usually be found in the wetlands; these are the region’s characteristic plants. In the riverbeds of the perennial rivers there may be some mayfly nymphs, Bee Shrimps (Caridina sp.), tadpoles, and the slender Flat-headed Loach (Oreonectes platycephalus). Under the water surface, Backswimmers can be found. On the water surface there are two types of Water Skaters; the larger one is Limnogonus fossarum, while the smaller one is Metrocoris lituratus. Also, Asian Common Toads (Bufo melanostictus) and Paddy Frogs (Fejervarya limnocharis) often hide among vegetation near the river. Along the upper course, dragonflies and damselflies are abundant. Indeed, experts have proposed the Tai Tong valley should be a Site of Special Scientific Interest because of its rich dragonfly population.


Pitcher Plant (Nepenthes mirabilis)

Flat-headed Loach
(Oreonectes platycephalus)

Paddy Frog
(Fejervarya limnocharis)


Water Skater ( Metrocoris lituratus)
 

Lower course

The lower course is severely polluted by organic substances, and the level of dissolved oxygen is very low. Only few organisms can survive in this grim, artificial environment. Wetland plants grow among the concrete crevices or some channel sections that haven’t been cleared. The river nurtures only a foreign fish species – Tilapia (Tilapia spp.). The dense vegetation along the upper stretches of the concrete channel, where there is minimal human disturbance, attracts a variety of dragonflies. Common birds are also seen in the channelised river.

 



Tilapia

Indigo Dropwing (Trithemis festiva)

Chinese Pond Heron (Ardeola bacchus)

Estuary

The estuarine mudflats are at the heart of the Inner Deep Bay wetland, which is international importance, especially for the waterbirds that feed, roost, and breed here. Every year, tens of thousands of waterbirds—including several globally endangered species—visit here. The mudflats are home to countless Blue-spotted Mudskippers (Boleophthalmus pectinirostris) and bright orange Fiddler Crabs (Uca arcuata). The estuary is a breeding ground for many fish, past records including Grey Mullet (Mugil cephalus), Japanese Eel (Anguilla japonica), Yellowfin Seabream (Acanthopagrus latus), Jarbua Terapon (Terapon jarbua), Japanese Seaperch (Lateolabrax japonicus), Spotted Scat (Scatophagus argus) and Tilapia (Tilapia spp.). From gei wai harvests we know that Greasy-back Shrimp (Metapenaeus ensis) is locally abundant.




Yellowfin Seabream (Acanthopagrus latus)

 
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