freshwater stream

Freshwater Stream

Introduction• Date : 14/9/2005• Site location : Chuen Lung• Time : 1:00 p.m to 3:00 p.m• Weather condition : Sunny and Dry• Water transparency : Fairly Clear• Smell : No Special Smell• Floating matters: Plastic bags, tin

cans, glass bottles, decayed leaves

Stream FeaturesGradient along the transect

Distance (m)

0 0.5 1 1.5 2 2.5 3

Water depth(cm)

6 11 17 15 10 18 10.5

26.9Bottom

30.5Above surfaceTemperature ( degree Celsius )

3875Bottom

4125Above surfaceLight intensity( Lux )

Other features

Chemical oxygen demand (mg/l)

Chemical factors

Ammonium content(transparency)

Phosphate content(ppm)

pH

Total dissolved solids (ppm)

Total suspended solids (mg/l)

Dissolved oxygen (mg/l)

0.5

28

6.42

25

0.227

3.69

8.8

Paramestorition hongkongensis (香港瘰螈 )Large, brownish newt

Under with red blotches

A predator of various invertabrates

Commonest in stream from September to March, when breeding take place

Most of the time spent on land

Pseudogastromyzon myersi

( 麥氏擬腹吸鰍 )

Strongly flattened fish

Mouth on the underside of the head

Dorsal fin yellow with red border

Food: grazes algae any oyanobacteria (藻青菌 )

Ptilomera tigrina (水黽 )

Long-legged bugs with raptorial front limbs and a slender beak.

Live in the most rapid part of riffles, especially numerous around the base of waterfalls

Strong jumpers that easily avoid capture

Euphaea decorate (豆娘若蟲 )

Found under stones

Have gills along the sides of abdomen

Colour: Dark grey to black

Development takes one year

Euphaea decorate (豆娘 )

Males have a black band across the hindwings

Females have more yellow stripes on the body and lack the wing band

Common found between April and October

Heptageniidae (蜉蝣若蟲 )

Tends to remain clinging to stones picked out of the water

Distinctly flattened with oral heads and plate-like gills

Brotia hainanesis (海南蜷螺 )

Streamlined shell reduces impact of water current

Hard shell protects against predator

Operculum(厴能 ) protects against predator

Found in fast running water and clean water

Marcrobrachium hainanense (海南沿蝦 )

Large chelate walking leg or defence against enemies

Found in slow running water and clean water

ConclusionDifferent animals have different features in order to adapt the environment.

As the light intensity is relatively low, there are only small number of plants.

There are many microhabitats along the transect line, e.g under stones.

More animals can be found in slow running water.

It is extremely important for us to protect the environment.

Cheung Lai Wan

Lau Suk Yan

Law Hoi Ling

Lau Tsz Leung

Leung Ka Man