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INTERNATIONAL EDUCATION CENTRE
(INTEC)
UNIVERSITI TEKNOLOGI MARA
NAME : MUHAMAD ALEIFF BIN TAJUDDIN
CLASS : 10M6
NRIC : 910304-08-6185
STUDENT ID : 2009623862
TITLE : PATTERNS IN DISTRIBUTION AND
ABUNDANCE OF ORGANISMS OF A
HABITAT
LECTURER : MDM SIVARANI D/O RAJADURAI
Aim:-
To investigate the patterns of the distribution and abundance of various organisms at the sea shore.
Abstract:-
The aim of the experiment was to study the distribution and abundance of the species
of organisms found at the sea shore. The distribution and the abundance of the species depend
on the biotic and the abiotic factor which was present in the location. The results of this
experiment show that the distribution of the sea grass has the greatest distribution and the
most abundant species. The result had been achieved by using the quadrat sampling technique
and the line transaction method.
Introduction:-
The word ecology comes from the Greek word ‘oikos’ meaning ‘house’. It is actually the
study of the interactions that determines the distribution and abundance of organisms within a
particular environment. Therefore, ecology is actually the study of living things in their home
environment or habitat. In this experiment we are going to study the ecology at the sea shore.
Sea shore is a
unique area in which it is
periodically submerged
and exposed by the tides,
twice daily on most
marine shores. Upper
zones will experience
longer exposure to air
and greater variations in
temperature and salinity.
Changes in physical
Figure 1: The sea shore where the investigation had been carried out.
conditions from the upper to the lower intertidal zones limit the distributions of many
organisms to particular strata. The oxygen and nutrient levels are generally high and renewed
with each turn of the tides.
Abiotic factors are the non-living elements of the habitat of an organism. They include
those related to the climate, such as the amount of sunlight, temperature extremes and
rainfall, and those soil-related including the drainage and the pH of the environment. In aquatic
habitats the oxygen availability in the water is very important. Other than that, the salt content
and the nutrients in the water also important to the organisms that live in aquatic habitat.
Environmental temperature is also an important factor in the distribution of organisms
because of its effect on biological processes. Cells may rupture if the water they contain freezes
and the proteins of most organisms denature at temperatures above 45℃. In addition, just a
few organisms can maintain active metabolism at very low temperatures, through
extraordinary adaptations enable some organisms, such as thermophilic prokaryotes, to live
outside the temperature range habitable by other life. Most organisms function best within a
specific range of environmental temperature. Temperature outside that range may force some
animals to expand energy regulating their internal temperature, as mammals and birds do.
The dramatic variation in water availability among habitat is another important factor in
species distribution. Species living at the sea shore or in tidal wetlands can dehydrate or dry out
as the tides recedes. The salt concentration of water in the environment affects the water
balance of organisms through osmosis. Most aquatic organisms are restricted to either
freshwater or salt water habitats by their limited ability to osmoregulate.
The amount of light in a habitat has a direct impact on the numbers of organisms found
there. Plants are dependent on light for photosynthesis. Any plant populations which are going
to thrive in habitats with low light levels must be able to cope with this factor. Animals are
affected by the light levels indirectly as a result of the distribution of the food plants. Seasonal
light change can also affect the reproductive patterns and without the cues from changing light
level , many aspects of animal behavior would be lost.
Biotic factors are the living elements of a habitat which affect the ability of a group of
organisms to survive there. For example, the presence of a suitable prey species will affect the
number of predators in the habitat. Other than that, finding a mate, territory, competition,
parasitism and disease also the examples of biotic factor.
A mathematical model that describes the relationships between predator and prey
population predicts that the populations will oscillate in a repeating cycle. The reasoning
underlying this model is straightforward. As a prey population increases there is more food for
predators and so, after an interval, the predator population grows too. The predators will
increase to the point where they are eating more prey than they are replaced by reproduction,
so the numbers of prey will fall. This will reduce the food supply of the predators, so they will
not produce as many offspring, and so their numbers will fall as well, allowing the abundance of
prey to increase again and so on.
Reproduction is a powerful driving force and the likelihood of finding a mate, or
achieving pollination, will help to determine the organisms which are found in any habitat. So, if
a single seed is dispersed to a new area, germinates, grows and survives, that species of plant is
unlikely to become a permanent resident unless other plants of the same species live in the
habitat. There must be males and females so mates can be found. Availability of mates has a big
effect on the abundance of any type of animal in an area.
Many species of animals show a very clear
territorial behavior. A territory is an area held and
defended by an animal or group of animals against
other organisms which may be of the same or
different species. Territories have different
functions in different animals but they are almost
always used in some way to make sure that a
breeding pair has sufficient resources to raise
Figure 2: Penguin territory in the pole.
young. The type and size of territory will help to determine which species live in a particular
community.
Parasitism and disease are biotic factors which can have devastating effect on
individuals. Diseased animals will be weakened and often do not reproduce successfully. Sick
predators cannot hunt well, and diseased prey animals are more likely to be caught. Some
diseases are very infectious and can be spread without direct contact such as avian flu which
can be spread in the faeces of an infected bird.
We have used quadrats to estimate the abundance of each species. A quadrat marks off
an area of ground within which you can make a thorough survey of which species are present,
and how many of each of them there are. If quadrat is too big, it is very difficult to do this
accurately. If the quadrat is too small, it does not give you a very good sample of the habitat as
a whole. Random sampling is usually carried out when the area under study is very large, or
there is limited time available. When using random sampling techniques, large numbers of
samples/records are taken from different positions within the area. A numbered grid should be
overlaid over a map of the area. A computer generated random number table is then used to
select which squares to sample in. For example, if we have mapped a representative zone, and
have then laid a numbered grid over it as shown below, we could then choose which squares
we should sample in by using the random number table. The advantage of using random
numbers is that no human is involved in the selection process.
Systematic sampling is when samples are taken at fixed intervals usually along a line.
This normally involves doing transects, where a sampling line is set up across areas where there
are clear changes. For example you might use a transect to show how gentrification or the price
of a convenience item changes with increasing distance from a zone of inner city
redevelopment.
A transect line is laid across the area you wish to study. The position of the transect line
is very important and it depends on the direction of the environmental gradient you wish to
study. It should be thought about carefully before it is placed. You may otherwise end up
without clear results because the line has been wrongly placed. For example, if the area of
redevelopment was wrongly identified in the example given above, it is likely that the transect
line would be laid in the wrong area and the results would be very confusing. A line transect is
carried out by drawing the transect line along the gradient identified. Alternatively, the
presence, or absence of a particular service or feature at each marked point, (e.g. every 100
metres), may be recorded. This is called systematic sampling.
Problem statement:-
Does abiotic and biotic factor affect the distribution and abundance of organisms at the sea
shore?
Hypothesis:-
The biotic and abiotic factors affect the distribution and abundance of organisms at the sea
shore.
Variables:-
a) Manipulated variable : Distance of quadrat from the shore.
b) Responding variable : Population distribution and abundance of organisms.
c) Fixed variable : Current velocity, Seawater pH, seawater content of iron,
nitrite, nitrate, phosphate, total chloride, free chloride and
magnesium hardness.
Materials& Apparatus:-
materials Apparatus
An orange pH indicator Nitrite indicator Chloride indicator Magnesium indicator Nitrate indicator Phosphate indicator Iron indicator
Sticks Measuring tape Quadrat Stopwatch Small quadrat
Table 1: Materials and apparatus
Procedure:-
a) Estimating population size.
1. Line transect method was used to estimate
the population size of organisms on the rocky
shore.
2. A suitable place was chosen as the area of
investigation.
3. A measuring tape was laid from the
sublittoral zone to eulittoral to splash zone.
4. Two sticks were used to mark the starting
and the ending point.
5. Next, a quadrat was placed at the right of the
line transect at four random places.
6. The species in each quadrat were
determined and the number of the species in
the quadrat was calculated. For small
organisms, a small quadrat was placed inside
the large quadrat.
7. The data obtained were recorded in the table.
b) Determine current velocity
Figure 3: Line transect that had been used in this experiment
Figure 4: Quadrat and small quadrat
1. A suitable straight stretch of water has been chosen. The distance was measured with
the tape measure.
2. The time taken by an orange to travel along the measured distance was recorded by
using stopwatch.
3. Step 2 was repeated three times to obtain the mean.
4. Then, the mean time was divided by the coefficient 0.85. This gave a more accurate
velocity for the stream because the water at the surface flows faster than the beneath.
5. The velocity was calculated using the formula: Velocity = distance ÷ time.
c) Investigate the pH of water sample, the free chloride/total chloride, the nitrite
content, magnesium hardness, phosphate content, iron content, and nitrate content.
1. A water sample was taken from an area of investigation.
2. The water sample was put into a clean beaker.
3. The pH of the water sample was test by using pH indicator by dipping it into the water
sample.
4. The colour change of the pH indicator was observed and compared with the standard
pH indicator.
5. Next, the paper indicator was dip into the water sample to test the total and free
chloride, nitrite content, nitrate content, phosphate content, iron content and
magnesium hardness.
6. Steps 1 until 5 were repeated with the water sample from different places from the
same area of investigation.
Results:-
a) Profile diagram.
Figure 5: Profile diagram of the sea shore.
Profile Position on line transect Note
(a) 0.0m – 2.0m Water
(b) 2.0m – 8.0m Rock & Water on the surface
(c) 8.0m – 15.6m Mostly water
(d) 15.6m – 23.52m Mostly flat rocks
Table 2: Description of the profile diagram
b) Quadrat sampling.
(a)
(b)
(c)
(d)
QAQB
QC
QD
Quadrat Position on transect line
Organisms found No. of organnisms
Note
A 17.61m - 18.12m Sea grass 95000 On the rock
surface
B 15.15m - 15.65m Sea grass 13750 Half rock and
half sea waterSea cucumber, 1
Crab 2
Organism A 5
C 10.64m - 11.15m Sea cucumber 1 In the sea
waterBarnacle X 4
Barnacle Y 1
D 5.76m - 6.27m Sea grass 85000 On rock
surfaceBarnacle Z 1
Barnacle W 4
Small fish 1
Table 3: Type and abundance of organisms which have been found in the quadrat sampling.
The ACFOR scale for the population size of species along the line transect
>100000 > 1000 >100 Abundant A 5
99999~ 80000 999 ~ 800 99 ~ 80 Common C 4
79999~ 60000 799 ~ 600 79 ~ 60 Frequent F 3
59999~ 40000 599 ~ 400 59 ~ 40 Occasional O 2
39999 ~ 0 399 ~ 0 39 ~ 0 Rare R 1
Table 4: ACFOR scale
The results from the 4 quadrats used
Quadrat Species found in the quadrat
Population size of each species in the quadrat (x
2500cm² if using 1cm² quadrat)
Number of species
found within the
quadrat
ACFOR
Scale
A (furthest from
the beach)
Sea grass 38 x 2500= 95000 1 C
B Barnacles X 5.5 x 2500= 13750
4
R
Barnacles Y 5 R
Sea cucumber 1 R
Crab 2 R
C Barnacles X 4 x 2500= 10000
3
R
Barnacles Y 1 R
Sea cucumber 1 R
D (closest to the
beach)
Barnacles Z 1
4
R
Barnacles W 4 R
Sea grass 34 x 2500=85000 C
Fish 1 R
Table 5: ACFOR scale according to each species of organisms in each quadrat
Kite diagram.
Quadrat A(furthest from the beach)
Quadrat B Quadrat C Quadrat D
-5
-3
-1
1
3
5
Barnalces 1
-5
-3
-1
1
3
5
Barnacles 2
-5
-3
-1
1
3
5
Sea cucumber
-5
-3
-1
1
3
5
Crab
-6-4-20246
Fish
Quadrat A Quadrat B Quadrat C Quadrat D
-5
-3
-1
1
3
5
Sea grass
Figure 6: Kite diagrams showing frequency and distribution of 6 species of organisms found at the sea shore.
c) Test for Water Sample
Water sample
pH Total iron content
Total phosphate
content
Magnesium hardness
Total nitrate content
Total nitrite
content
Chloride content
1 8 0 15 25 gpg 0 0 Total - 0
425ppm Free - 0
2 7 0 5 25 gpg 0 0 Total - 0
425ppm Free - 0
3 7 0 5 25gpg 0 0 Total - 0
425ppm Free - 0
Table 6: Result for Water Samples’ Test
d) Current velocity
i) Distance = 2m
ii) T1 = 52.6s
T2 = 64.0s
T3 = 73.0s
iii) Taverage = 52.6+64.0+73.0
3
= 63.25s
iv) T =63.250.85
= 74.4
v) Current velocity =2.074.4
= 0.02688 ms-1
Discussion:-
Analysis of data:
Figure 6 shows the profile diagram of the sea shore from the sublittoral zone to
eulittoral to splash zone. Area labelled (a) is totally immersed in the sea water. Area labelled (b)
is a large rock with a small part of sea water on it. Mostly sea water at the area labelled with (c)
and mostly flat rocky surface covered the area labelled (d). Quadrat 1(QA) is in the (d) area
which is on the flat rocky surface. Quadrat 2(QB) and quadrat 3(QC) were in the (c) area in which
QB was at the area consisted of half sea water and half rocky surface. The last quadrat which is
on the surface of the large rock was quadrat 4(QD). Table 2 shows the description of the profile
diagram of the sea shore. The table gave us the information about the position of each area on
the line transection. Area (a) was from 0.0m to the 2.0m away from the sea while the area (b)
was from 2.0m to the 8.0m, followed by area (c) from 8.0m to the 15.6m distance away from
the sea. The last area which was (d) located at the 15.6m to 23.52m away from the sea.
Table 3 gives us the information about the species and the abundance inside the
quadrat. For the QA, it was placed at the 17.61m to 18.12m on the line transect. The species
that we found there was only sea grass on the rock surface. In the case of quadrat Q B, it was
situated at the 15.15m to 15.65m on the line transect. The species that we found in the quadrat
was barnacles X and Y, sea cucumber and crab. We found the barnacle X and Y on the rock
surface while the crab and the sea cucumber were in the water. The third quadrat which is QC
was placed at the 10.64m – 11.15m. The species that we found here was barnacle X and Y again
and sea cucumber as well. The last quadrat consists of sea grass, barnacle Z and W and small
fish. The quadrat was situated at the 5.76m – 6.27m. We found all of these species on the large
rock that had water at its surface.
Table 4 shows the ACFOR scale that we used to make a kite diagram. Table 5, was the table that
I used to make reference to complete the kite diagram. Figure 7 was the kite diagram that we
obtained from this experiment. We can see the pattern for each species. For barnacles X, we
can see that the species was large in number in quadrat B and C. Same pattern was shown by
the barnacles Y and sea cucumber. Crab was only found in quadrat B while fish was only found
in the quadrat D. Lastly, the sea grass was large in number in the Quadrat A and Quadrat B. It is
clearly depicted that the most related abiotic factors for the species that live in the ecosystem
are the exposure towards the sunlight, humidity, water salinity and the water current during
low tide. In quadrat A and D, most of the sea grass grows on the surface of the rock to obtain
optimum exposure towards the sunlight. Meanwhile, in quadrat B and C, the growth of the
barnacles species mostly seen at the side of the rock which indicates us about the relative
humidity and the little exposure of the sunlight on them. This case also tells us about the
durability of the barnacles’ species towards the water current. The discovery of the sea
cucumber in quadrat B and C along the line transect at the seashore shows us that the species
can live in water with high salinity.
Another reason why the distribution of organisms was found to be like this lies in the
level of H+ ions and OH- ions of seawater. Lower H+ ions will indicate that the seawater is acidic
while higher OH- ions content will resulted in alkaline seawater. Most marine and aquatic
organisms can only live in neither acidic nor alkaline condition. Based on the results above, we
can see the relationship between the level of pH value of seawater with the abundance and
distribution of marine species. The phosphate content of seawater dropped from 15 ppm in
water sample A into only 5 ppm in water sample 2 and 3. Around the area in which water
sample 1 was taken, the abundance of sea grass found was very high (with 15 ppm of
phosphate) while there was no other species of organisms found in that particular area.
Meanwhile, around the area in which water sample B and C was taken (with 5 ppm of
phosphate), the abundance and distribution of seed grass was completely zero whereas the
number of other marine organisms increases. This phenomenon is best explain with the fact
that higher concentration content of phosphate in seawater may resulted in the destruction in
the sensible biological balance of marine habitats. Higher phosphate content is the most
favourable condition for seed grass, blue and green algae to live and reproduce rapidly while
for other marine organisms it is vice versa. This is because large number of algae (due to the
high phosphate content) may grow on the body of other marine organisms and eventually kill
them. Even the algae found on corals called zooxanthella will grow very fast and the corals will
be badly affected. Based on the findings in the internet, the suitable condition for the growth of
marine organisms will be between 5 to 20 ppm.
Table 6 above shows the pH value and chemical content of seawater found at the
experiment site. From the result we can see the water sample 1 that was taken in front of a
rock contain 0 ppm of iron, nitrite, nitrate, total and free chloride. The pH value was 8 and it is a
sign that seawater sample taken from that place was slightly alkaline. Its magnesium hardness
was found to be 425 ppm and 15 ppm of phosphate content. For water sample 2 which was
taken behind a rock, it has a pH value of 7 which is neutral. Despite its neutrality, that particular
water sample still has the same magnesium hardness which was 425 ppm and 0 ppm of iron,
nitrite, nitrate, total and free chloride content. However, its phosphate content was found to be
different with water sample A that is 5 ppm. As for water sample 3, it was taken near the
quadrat 1 location and it still has 425 ppm of magnesium hardness, pH value of 7, phosphate
content of 5 ppm and iron, nitrite, nitrate, total and free chloride content of 0 ppm.
The (d) shows the calculation involving in determining current velocity. A distance of 2m
was measured and an orange was used as the float thing. 3 trials were done in order to obtain
the average value of the time taken for the orange to travel 2m distance on the seawater. The
time taken was 52.6 s, 64.0 s and 73.0 s for trial 1, 2 and 3 respectively. The average time taken
was found out to be 63.2 s. The average time taken was then divided by 0.85 to give a more
accurate velocity for the stream because water at the surface flows faster than that beneath
and the new average time taken was 74.4 s. For the calculation of current velocity, the distance
of 2 m was then divided by 74.4 s. The current velocity was found to be 0.02688 ms-1.
Validity and reliability:
It is vivid that the validity of the experiment conducted above is satisfying enough. This
is because in the experiment, there were 2nd time and 3rd time in taking the reading of the time
taken for the orange to complete the 2m journey on seawater freely so that average reading
can be taken. As for the number of organisms found, although the counting process was
actually been done once but it is highly accurate because more than one person involved in the
counting process. Therefore we can say the result obtained is valid.
Furthermore, the reliability of this experiment is said to be correct and reliable. This is
because the results obtained by the other groups who conducted the same experiment showed
much or less the same pattern and trend. Whenever the same pattern and trend are obtained
among the other persons or groups who conducted the same experiment, therefore we can say
that the results obtained are reliable.
Temperature of seawater: 27oCCurrent velocity: 15 seconds to move 0.5 m = 0.033 ms-1
pH
value
Iron
content
(ppm)
Nitrite
content
(ppm)
Nitrate
content
(ppm)
Phosphate
content
(ppm)
Total
chloride
content
(ppm)
Free
chloride
content
(ppm)
Mg
hardness
(ppm)
9 0 0 0 15 0 0 425
Table 7: Other group’s result
Below are the results of other group (Group B) which did the same experiment. The
results obtained is much or less the same with our current result.
Quadrat (0.25 m2)
Distance of quadrat from
sea (m)
Species found Population size (x 2500 if 1 cm2 quadrat was used)
1 0 Green fungusPurple fungusBrown fungusBig barnaclesSmall barnaclesSnails
9113156015
2 5 BarnaclesBrown fungusGreen fungusPurple fungus
31315
3 10 Green fungusPurple fungusBlack fungus (species Y)Brown fungusBarnaclesBlack fungus (species X)
2566
10415 x 2500
4 15 Black fungusSnail
36 x 25001
5 20 Red insectSpiderBlack, soft body organism
111
6 25 Black shellSea cucumberEarthworm
111
Table 8: Other group’s results
Evaluation:-
Experimental errors
There are several errors that make our results to be inaccurate. The first error which can
be occurred is when we make the line transect. The measuring tape that we used should not
place on the large rock. The measuring tape should be in the straight line .This can be done by
hung the measuring tape above or beside the area of investigation.
The second error in this experiment happened when we need to compare the colour
change of the paper indicator with the standard colour. Human error is more likely to occur.
This is because normal human’s eye cannot detect the slight change of the colour. So this will
affect the accuracy of the result.
The third error occur when counting the number of sea grass, it is more likely to be
inaccurate. This is because, sea grass is a minute species and they are very closely to each
other. Plus, they are also found in large number in a small area. Thus it is impossible to count it
one by one with the naked eye. This can be improved by using device such as magnifying glass.
Besides that, another source of error
that was found is that the camouflage effects of
the organisms. As example, one might mistaken
a small crab with a rock while counting the
number of organisms found. The small crabs in
fact have similar markings on their body that
match perfectly with surrounding
environments. Therefore, a thorough check
should be done by having the counting process
involved more than one person or the counting
process should be done by the people with
sharp-sightedness so that the camouflage effects
of organisms can be easily spotted.
Figure 7: Fish that used camouflage technique.
Limitation
There are several limitations in this experiment that cannot be avoided. The current
velocity was determined during the low tide. So the current velocity is not the real velocity as
we do not determined the velocity during the normal tide. The time for the orange to travel
along the 2m distance is affected by the velocity of the wind. If the velocity of the wind is fast,
so the time taken for the orange to travel the 2m distance is short and vice versa.
The low tide also did not give all the type of species present in the area of investigation.
This is because the species during the high tide may not present when low tide. So, this will
affect the type and abundance of organisms there. Besides that, due to the low tide condition,
some organisms were found out to be trapped in between the rocks. This was what happened
where many of the sea cucumbers, small crabs and small fish in that particular area. In some
cases, there were small fish and crabs trapped in small watery area on a rock and the rock itself
has become the new temporary microhabitat for these organisms. Their presence will
somehow disrupt the original balance of the site’s ecosystem hence affecting our result.
Further investigation
The experiment can be further continues by trying the line transect method in the forest
instead of sea shore. Then, make the kite diagram for the organisms in the forest. After that,
thorough comparison of the kite diagram for organisms at the sea shore and the forest should
be made. Later, we must observe whether both of the kite diagrams show the same pattern or
turn out to be different.
Conclusion:-
In conclusion, the distribution and abundance of a species of a specific organism at the sea
shore depend on the biotic and the abiotic factor. So, the hypothesis is accepted.
References:-
Books:
i. Edexcel Biology for AS, Hodder Publication - C J Clegg
ii. Edexcel Biology for AS, Pearson Publication - Fullick A
iii. Biology ISE, Thomson Brooks/Cole - Solomon, Berg, Martin
Websites:
1. http://en.wikipedia.org/wiki/Quadrat retrieval date: 15 July 2010
2. http://geographyfieldwork.com/urban_sampling.htm retrieval date: 15 July 2010
3. http://en.wikipedia.org/wiki/Abiotic_component retrieval date: 15July 2010
4. http://en.wikipedia.org/wiki/Biotic_component retrieval date: 15July 2010
5. http://en.wikipedia.org/wiki/Aquatic_ecosystem retrieval date: 15 July 2010
6. http://en.wikipedia.org/wiki/Abundance_(ecology) retrieval date: 15 July 2010