Transcript F.6 Bio - CCC Ming Yin College

The C.C.C. Ming Yin College
19 / 1 / 2006
Introduction
Aims
1. To compare the biodiversities at
site A and site B.
2. To promote our environmental
awareness.
Locations of Site A & Site B
Profile of Site A
The Profile of Site A
2.7
2.3
1.9
1.5
1.1
0.7
-10
0.3
Distance
along
0
-20
-30
-40
Water
Depth/cm
Profile of Site B
The Profile of Site B
-4
-6
2.7
2.3
1.9
1.5
1.1
0.7
0.3
-2
Distance
along
0
-8
-10
-12
-14
Water
Depth/cm
Site A
Site A
1. The area is shaded by canopy of
2.
3.
4.
5.
6.
trees.
Light intensity is low.
Fallen leaves can be found.
The sediment is mainly composed
of sandstones.
The water is clear.
Slow waterflow.
Site B
Site B
1. Large number of stones with
2.
3.
4.
5.
different sizes lie at the bottom of
the stream.
Fast waterflow.
Aquatic animals are rarely seen.
Adequate sunlight.
Cool but not windy.
Water Sampling
1. Ammonia Content (ppm)
Site A
0.167
Site B
0.100
2. Phosphate Content (ppm)
28
6
3. pH
7.0
6.84
0.52
0.52
4. Total Dissolved Solids
(ppm)
5. Total Suspended Solids
(mg/l)
6. Dissolved Oxygen (mg/l)
7. Chemical Oxygen
Demand (mg/l)
Site A
8
Site B
/
5.51
4.78
/
2.80
1. Suspended solid particles of the water
sample cannot be determined in site B.
Reason: Water vapour in the air was absorbed
by the filter paper before weighing yesterday.
2. Chemical oxygen demand of the water
sample cannot be determined in site A.
Reason: Personal error. Too much permanganate
solution was added after end point was reached.
Physical Factors
Light Intensity
Water
Temperature
Site A
Site B
Surface
0.5
5.5
Bottom
0.5
4.5
Surface
19.3
19.3
Bottom
19.3
19.1
0.1 m/s
30 m/s
Average Flow Rate
Freshwater Plants
All the plants found in Site A and Site B are different.
Site A
Name
Taro 芋
Sweet Flag石菖蒲
Approx. Density
7
2
Site B
Name
Day-flower竹節草
Water Celery 水芹
Water Cress西洋菜
Greaterduckweed浮萍
Moss蘚
Arbitrary Unit
1
1
2
100
1
Freshwater Animals
Site A Site B
Mayfly Nymph
蜉蝣若蟲
Large Stream Snail
海南蜷螺
Viviparous Snail
石田螺
Approx.
Density
Approx.
Density
1
3
22
0
0
12
Site A
Site B
Approx.
Density
Approx.
Density
Dragonfly Nymph
蜻蜓若蟲
0
1
Small Stream Leech
舌蛭
Ranshorn Snail
凸旋螺
1
1
0
12
Site A
Site B
Approx.
Density
Approx.
Density
Damsefly Nymph
豆娘若蟲
0
2
HK Newt
香港瘰螈
2
1
Reservoir Snail
瘤擬黑螺
8
1
Goby
鰕虎魚
3
0
Comparison for the number of organisms and
the biodiversity in site A and site B
‧Plants
In general, there are fewer plant species in site A than in site B.
However, the total numbers of plants in the two sites are about the
same. A total of 9 plants can be found in site A and a total of 10
plants can be found in site B. There is no common plant in the two
sites.
A total of 2 plant species can be found in site A, namely, taro
and sweet flag. Taro is the dominant species in site A, 7 of which
can be found. Only 2 sweet flags can be found.
A total of 5 plant species can be found in site B, namely, dayflower, water celery, water cress, greaterduckweed and
moss. Greaterduckweed is the dominant species in site B, 5 of
which can be found. While for the other species, only 1 or 2 of
which can be found.
Site A has a large tree, so there is a large
canopy and less sunlight can reach the
freshwater. Plants can’t get enough light for
photosynthesis so that there are little freshwater
plants. There are only Taro and Sweet Flag.
Site B is exposed to sunlight directly so there
are many different species of short freshwater
plants in site B such as Day-flower, Water Celery,
Water Cress, Greaterduckweed and Moss.
‧Animals
In general, there are fewer animal species in site A than in site
B. However, there are slightly more animals in site A than in site B.A
total of 37 animals can be found in site A and a total of 33 animals
can be found in site B. Mayfly nymph, small stream leech, Hong
Kong newt and reservoir snail are found in both sites.
A total of 6 animal species can be found in site A, namely,
mayfly nymph, large stream snail, small stream leech, Hong
Kong newt, reservoir snail and goby. Large stream snail is the
dominant species in site A, 22 of which can be found. Reservoir
snails are the second most abundant organisms in site A, 8 of which
can be found. For the other species, only 1-3 of which one can be
found.
A total of 8 animal species can be found in site B, namely,
mayfly nymph, viviparous snail, dragonfly nymph, small
stream leech, ranshorn snail, damsefly nymph, Hong Kong
newt and reservoir snail. Viviparous snail and ranshorn snail are
the dominant species in site B, 12 of each of which can be found.
For the other species, only 1-3 of which can be found.
Reasons why site A has larger number of each
species while site B has greater diversity of
organisms
At site A, the phosphate content in the water
is much higher than that at site B due to inorganic
fertilizer used by farmers nearby and slow water flow
rate. Phosphate accumulates. The high phosphate
content favours the growth of photoplankton. The
slippery stone surfaces indicate the large population
of photoplankton.
The animal found in site A is mainly snails, a
kind of filter feeder which feeds on photoplankton. As
there is plenty of food, the growth of snail population
is favoured.
The physical environment in these 2 sites
are different because:
1. The huge canopy of a tree covers the
surface of the stream, reducing light
intensity reaching the stream.
2. The fallen leaves of a tree increase the
nutrients available in the stream since
they can be decomposed, releasing
ammonia and phosphate.
3. The roots of the trees anchor the soil
particles tightly, preventing soil erosion.
4. Mosses can secrete acid, breaking down
large rocks into smaller soil particles.
5. When the dead bodies of living organisms
such as insects decompose, it leads to an
increase in nutrients available in the
stream.
Photos From Polluted Area
Reflections from polluted area
Water in polluted area is smelly, turbid and still. A lot
of rubbish can be found, such as tyres, glass, plastic
bottles and suspended organic substances.
The government should construct sewage pipes to
collect and treat household sewage before discharge.
People lack awareness of environmental protection
that should be raised by the government through
education.
The government should set up laws and impose
heavy fines on those who discharge untreated sewage
into rivers directly.
Limitations of this field study
• Time of investigation
Since the investigation in this field study
only covers a particular season(namely,
winter), we are not allowed to obtain a full
picture of the ecology of the two sites(site A
and site B) throughout the year and we may
not understand the whole thing thoroughly.
For instance, a certain kind of organism may
be active in summer, but not in winter.
• Lack of sophisticated apparatus and skills to
use them
Since we do not have sophisticated
apparatus and the skills to use them, some
factors and organisms of the field cannot be
studied. For instance, we cannot count the
number of micro-organisms, such as bacteria
and fungi in the stream and we cannot study
them thoroughly.
• Changing environment
The reading varies from time to time shows
that the environment is changing.
Conclusion
After this field study, we can see that the organisms
and the environment are interacting with each other
continuously and form a stable ecosystem.
For instance, the canopies of the tree affects the
light intensity on the water surface and at the bottom,
thus affecting the organisms.
Moreover, human activity has adverse effect on the
ecosystem. For example, household sewage directly
discharged into the stream and the dumped inorganic
fertilisers increase the phosphate content in water.
Improvements
1) For constrasting sites,we should avoid choosing
somewhere just near other groups ,e.g. a bit lower
position so the results will not be so easier affected by
other groups' working.
2) We should have a better group coordination before
collecting data at the stream and doing experiments in
order to a better job allocation.
3) We should have more preparation e.g. finding more
information about organisms in stream and the ways to
proper use of apparatus before going the field trip.
Our feedback
We are glad that we learn many things and gain many valuable
experiences from this field trip. Firstly, it a great chance for us to
contact with nature.
We know more about the ecosystem of stream. We can also
practise some skills learning from books. Moreover, we can use
many modern apparatus which are not available in school laboratory.
The trip also help us to know our weaknesses---poor job
allocation and presentation skills. To improve this situation, we will
try the best to have a better communication and have a rehearsal
before presentation.
All in all , the trip help us in both academic and personality
development. It's a precious memory for us.
We were collecting
those data we
needed.
It is the first time for us
to see a Hong Kong
Newt .
Every one of us actively
participated in the Field
Study to collect data and
samples.
Group Members List
Site A
Site B
Chan Kwing Lam
Chu Ho Shing
Lam Chung Kwun
Chu Nim Chi
Li Pui Sze
Lo Lai Ping
Chan Sze Chun
Ho Kin Tak
Li Pui Sun
Tse Yuet Sim
Yeung Pui Shan