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IB Biology Field Trip Pranburi
Date: 18 – 21 February 2010
Objectives of the Field Trip:
1. To learn and understand the various types of basic fieldwork techniques used to
investigate ecosystems and species diversity.
2. To investigate and study the ecological environments of the rocky shore and mangrove
swamp.
3. To gather data to investigate the major organisms present in each habitat and their
adaptations to the environment.
4. To find out the effect of the main physical factors on the distribution of organism and the
interrelationships existing among organisms.
5. To foster inquiry and allow students the opportunity to plan and conduct their own
ecological investigation in a habitat of their choice (rocky shore, sandy shore, or
mangrove swamp).
Part 1 Description of Habitat
ROCKY SHORES (Background Information)
Because the tide rises up and down twice a day things at the high tide level get much less water
than things at the bottom. This gives rise to an extraordinarily large number of different ways of
surviving on rocky seashores. Nearly every phylum has a representative on the shore. What's
more, all these creatures are crammed into the small physical space between the tides. At low
tide, the organisms that live on the seashore tend to sit there quietly, almost begging you to
measure and count them. Many of them are just the right size for such activities. Most people
(even cool ones) will admit to enjoying being on seashores, wrestling with crabs and identifying
with algae. The other major physical factor that controls what can live on a shore is wave action.
Exposed shores have lots of wave action and sheltered shores have little.
Partially because of the extreme environmental gradient resulting from the rise and fall of the
sea, the organisms on the shore live in distinctive horizontal bands or zones. We can use this
fact to divide the shore up into convenient zones for us to study. In short, if you are a student,
rocky shores provide you with a vast array of easily carried out investigations and projects.
Exposed Rocky Shores
Rocky shores usually face into the open sea and the prevailing wind. This means they generally
have bigger waves than sheltered shores, which face away from the open sea and the
prevailing wind. South to southwesterly facing exposed shores get more sunlight than sheltered
ones, are more susceptible to drying and in general are not hospitable places for most intertidal
organisms. Because reality is never as simple as we imagine, there are exceptions. Offshore
reefs or islands, for example, can shelter shores that would otherwise endure heavy wave
action.
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Splash zone
The zone above the highest tides. It's splashed by spray but not covered by the sea. It's not
terrestrial or truly marine.
Upper shore
The top of this zone is covered by the sea for less than 1% of the year. The bottom of it for
about 20% of the year
Middle shore
The top is covered for about 20% of the year; the bottom for about 80% of the year.
Lower shore
The top of this zone is covered for about 80% of the year; the bottom for less than 1% of the
year.
The Tides
The main cause of the tides is the Moon; the Sun has an effect as well.
The Moon's gravity causes the oceans to bulge out (tidal bulges) on opposite sides of the Earth
simultaneously. We perceive these as high tides. Because of the rotation of the Earth on its own
axis the tidal bulges slosh back and forth causing us to perceive high and low tides. There are
roughly two high tides and two low tides every 25 hours. There are usually about 6 and a bit
hours between high and low tide. This is the DAILY pattern.
Because the Moon orbits the Earth, sometimes it is pulling in line with the Sun and sometimes it
is pulling at an angle to the Sun. When it is pulling in line the tidal bulges are big. When it is
pulling at an angle the tidal bulges are small. This produces the LUNAR/
circa MONTHLY pattern.
When the Moon is new or full it is in line with the Sun. When it's a half
Moon it is at an angle to the Sun. This results in a monthly/lunar pattern
as follows: New Moon: (No Moon visible in sky), Moon and Sun in line,
bulges big, high tides extra high low tides extra low. These are called
SPRING tides (nothing to do with the season)
Half Moon: (Roughly a week later), Moon and Sun at an angle, bulges
smaller, high tides not so high low tides not so low. These are called
NEAP tides.
Full Moon: (Roughly a week later), Moon and Sun in line, bulges big,
high tides extra high low tides extra low. These are called SPRING tides.
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Half Moon again: (Roughly a week later), Moon and Sun at an angle, bulges smaller, high tides
not so high low tides not so low. These are called NEAP tides.
New Moon: (Roughly a week later) No Moon visible in sky, Moon and Sun in line, bulges big,
high tides extra high low tides extra low. These are called SPRING tides
Thus, roughly speaking, we get a week of spring tides followed by a week of neap tides followed
by a week of spring tides followed by a week of neap tides. You do not of course jump from one
to the other it is more in the nature of a steady change.
There is also a YEARLY pattern:
Around the equinoxes (March 21st and September 21st) the spring tides are extra "springy" the
highs are exceptionally high and the lows are exceptionally low. Correspondingly the neap tides
at this time of year are extra "neapy" the highs are not very high at all and the lows are not very
low.
Around the solstices (June 21st and December 21st) the spring tides are not so "springy"
(higher and lower than neap tides but not greatly so) and the neap tides are less "neapy" (highs
a bit higher and lows a bit lower than at other times of the year).
The reason for this is to do with the proximity of the Earth, Moon and Sun and the angle of the
Moon's orbit about the Earth.
Zonation: Factors affecting the distribution of organisms
Below is a summary of the main factors, which can influence the distribution of organisms on
the seashore.
DESICCATION means drying out. This occurs because at low tide, the upper and middle shore
are not covered with water.
WAVE ACTION more wave action means the water splashes higher and so the zones occur
higher up on the rocky shore. The strong force produced by powerful wave action will determine
not just whether that organism can remain attached to the rock but also may have an effect on
its growth. E.g. Bladderwrack displays substantial variation in its shape, size and the number of
bladders; limpets differ in their shell height – shell height tends to be lower on exposed rocks
than sheltered areas.
LIGHT is needed for photosynthesis. Algae need to be in seawater for this to occur. However,
the water will filter off some of the wavelengths of light and reduce the intensity. Small algae,
e.g. some of the red algae, will photosynthesise with very little light and occur under other larger
algae. Algae in mid-lower shore require accessory pigments to absorb lower amounts of light
penetrating the water. Light is required for aquatic plants, mangrove trees, algae and other
producers which are a critical trophic level for the ecosystem.
TEMPERATURE - immersion in water buffers against temperature change. Upper shore
species will have to tolerate the greatest variation in temperature whilst it has the least affect in
the lower. High temperatures will increase the effect of drying out – this increases salinity in tide
pools. Estuaries range in temperature with the tides and amount of sunlight exposure.
ASPECT is the direction the shore faces. South facing will have more illumination and warmth,
but dries faster; north is cooler, darker and less likely to dry out. Thus, on a north facing slope
community bands will be wider and higher up the shore. Catenella (red alga) colonises north
aspect whilst on south facing ones the lichen, Lichina replaces it.
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SLOPE. A flatter rocky shore may provide a greater area of substrate for colonising and will not
drain as fast as a steeper one.
TURBIDITY is the cloudiness of the water. Large amounts of plankton can increase the
turbidity, as will detritus, fine inorganic matter and sewage pollution. This restricts the light
reaching the algae on rocks and beneath the surface in an estuary.
SUBSTRATE - The hardness and size of rocks and boulders will influence an organism’s ability
to attach itself. Soft rocks will be suitable for burrowers, e.g. piddocks. Large boulders and rocks
give good shelter for animals and the angle of dip of the rock strata may produce more crevices
and pools. If stones are too small they will be mobile, moving around in the surf and so prevent
any organism from attaching itself to the rock. Substrate in an estuary is the lower surface of the
estuary bed. It is often muddy or sandy and can be rich with sediment.
FRESHWATER - Seepage of water from the cliff can dilute the seawater. Few of the organisms
on the shore can tolerate salinity changes. Upper shore rock pools are vulnerable to salinity
variation as water runs off the cliff. The flow of freshwater towards the ocean in an estuary and
the tidal action of the salt water in and out make the estuary a special environment which
contains a gradient of salinity.
BIOTIC - These are the biological factors influencing the community. Algal turf, like Laurencia
and Chondrus, will slow down the drainage on the shore and reduce desiccation.
Grazing is very important. A high concentration of limpets will reduce the establishment of the
normally dominant brown seaweed. Removal of limpets from a shore, e.g. due to oil pollution,
results in a sudden "bloom" of algal growth, usually green.
Inter-specific competition occurs when niches of different species overlap. The brown algae
knotted wrack occupies a similar position in the middle shore to bladder wrack (another brown
algae). The latter survives wave action better than the former, which is found on sheltered
shores. Where they both occur competition allows the former to dominate as it lives for many
years longer. Barnacle species (Chthamalus and Semibalanus) are also known to exhibit
zonation due to competition, causing each species to settle for their “realized niche” instead of
their “fundamental niche.”
The bladder wrack algae have a "whiplash" effect, where water movement causes a sweeping
action of the alga across the rock and prevents the attachment of algae spores and the settling
of planktonic larvae. In this way it competes with barnacles. If the latter does manage to become
established it may push out the wrack.
Populations cannot become established unless juvenile forms are available to colonize the
rocks. This is called Supply-side Ecology. Most organisms living on the shore use the sea to
disperse their young. The algae have microscopic spores and animals like topshells have
larvae, which settle on to the rock to begin growth. If these young are not available the
populations cannot be established.
You may find limpets, periwinkles, whelks, oysters, crabs, and marine isopods on the rocky
shore – engaging in various community interactions.
SANDY SHORES (Background Information)
The seashore environment is a very formidable one. During high tide, the shore is covered by
seawater, and is part of the sea. When the tide recedes however, the shore becomes exposed,
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and for several hours, is reclaimed by the land.
The shore (or littoral/intertidal zone) is the region between the highest level of high water spring
tides and the lowest level of the low water spring tides. Any organism inhabiting the intertidal
zone must be able to tolerate the extremes of environmental conditions that occur between tidal
cycles.
Intertidal animals and plants are thus subjected to an alternation of exposure to the atmosphere
and the sea. This raises many problems other than the basic ones of food and shelter for their
survival. Each organism has evolved its own special adaptations to overcome these challenges.
Its shortcomings are, in turn, reflected in the habitat it eventually chooses. In addition to all this,
man-made activities continue to threaten to pollute the environment.
Most of the resident intertidal shore creatures are found in the lower half of the intertidal zone.
There is little animal life in the upper third of the littoral zone. The number of organisms
increases as one progresses down to the subtidal zone. Burrowing animals can be found below
the surface on a sandy shore if there is sufficient moisture or interstitial water (i.e., water
trapped between the sand particles). Often, during low tide, when the substrate dries up under
the hot sun, they burrow even deeper to escape the crippling effects of desiccation. Hence, to
the casual observer, the shoreline may appear barren or impoverished.
The Strand Line
This is the part of the intertidal zone where debris, algae and other
flotsam (floating debris) are left behind by the previous receding tide.
Many organisms find shelter here, feeding on the algae and other
organic material.
Along sandy shores, Ulva is the most common stranded algae while
on rocky shores, Sargassum is predominant.
Along the strand line are also found the
skeletal remains of many marine
animals. Seashells (gastropods and
bivalves) dominate. The gastropod shell
shown here has most likely been broken
by crabs and later eroded by wave
action. In some cases, shell boring barnacles, sponges and worms
further perforate the shell.
The globose sea urchin test (below) which belongs to the banded urchin, Salmacis, is actually
the animal's exoskeleton and is made up of separate plates. In some specimens, the
characteristic mouthparts can still be found on the ventral surfaces.
Cuttlefish bones are actually the internal skeleton of this important
food mollusc which is related to the octopus. The bone is frequently
collected to serve as a calcium supplement for cage birds.
Adapted from: http://mangrove.nus.edu.sg/pub/seashore/text/002.htm
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Sand dollars (Echinoidea) are active just under the sand at low tide near the tide line. Look for
their trails or round impressions as they sift sand for food. Their closest relatives are the sea
urchins.
ESTUARY AND MANGROVE SWAMPS (Background Information)
An estuary is a body of water that is supplied with one or more rivers/streams flowing into it, and
with a free connection to the coast.
Estuaries make up zones of transition between river and ocean environments. Estuaries are
subject to both marine influences, such as tides, waves, and the influx of saline water; and river
influences, such as flows of fresh water and sediment. High levels of nutrients are supplied by
the ocean and river waters. Estuaries are some of the most productive of natural habitats.
When the ocean rises toward high tide, salt water flows into the estuary. When the ocean
moves toward a low tide, water flows into the ocean from the estuary.
Mangroves are some of the few tree species that are able to survive in swamps forming from
estuaries. Mangroves produce roots that go deep into the mud to extract nutrients. Crabs,
snails, sponges, crustaceans, snails, fish, algae, and other organisms including the amphibious
species mudskippers find their homes in these ecosystems.
Mangrove swamps serve an ecologically important role as fish nurseries and they also protect
the coast during storms. They are among the most rapidly degraded environments in the world,
as many people live on or in estuaries, polluting them. They are also lost through development
of coAstal areas for tourism.
The Mangrove Trees
The extremely saline mud and exposure have caused the trees to
develop features that are common in desert plants, e.g., thick, waxy and
fleshy leaves. Some have breathing roots (pneumatophores) to help them
obtain oxygen from the air since the mud is often waterlogged
and highly anaerobic. These trees and their roots are vital in
consolidating the mangrove swamp and act as breakwaters to
prevent erosion.
Rhizophora
Family Rhizophoraceae
Order Myrtales
Rhizophora is characterized by its stilt roots (left) and vivipary
(right) (the retention of the embryos, fertilized fruits, on the
parent, plant, obtaining nutrition from it until the seedling
stage). They then fall off and implant themselves in the mud or
drift off with the tides. This tree is the source of famous bakau
wood which is very resistant to sea water and pests.
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Bruguiera
Family Rhizophoraceae
Order Myrtales
The other genus is Bruguiera, which is easily
distinguished from Rhizophora by its "kneed"
pneumatophores. (Both reach heights of up to 20m).
Bruguiera roots
Bruguiera calyx
Avicennia
Family Verbenaceae
Order Tubiflorae
Both Avicennia and Sonneratia are common mangrove trees,
especially Avicennia.
Avicennia roots
Both have pneumatophores, but can be separated by the lower
surfaces of the leaves of Avicennia being paler than the dorsal, its
flowers being small, orange or yellow, the fruit heart-shaped.
Avicennia is able to secrete the excess salts through its leaves and
hence maintain the osmotic balance. (Height up to 30m).
Avicennia fruit
Sonneratia
Sonneratia
Family Lythraceae
Order Myrtiflorae
Sonneratia has more oval leaves, the lower
surfaces green, the larger white flowers with
a long style, and the fruit globular. (Height up
to 30m).
Adapted from: http://mangrove.nus.edu.sg/pub/seashore/text/002.htm
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Sonneratia leaves
and fruits
Part 2 Investigations
1.
THE ROCKY SHORE INVESTIGATIONS
A.
Abiotic Factors
1. Temperature
Use a thermometer to record the air temperature changes throughout the study time.
2. pH
Record the pH of the sea water by taking 3 samples of the sea water in small sample
bottles. This can be tested using the pH probe later.
3. Wave frequency
Determine this by recording the number of waves hitting the shore per minute. Complete this
at low tide and high tide (or at least on two occasions during your study time – before and
after you do your survey). Three trials are needed at each time.
4. Wind direction
Hold the light string above your head and determine the wind direction by observing the
direction of its movement using the compass. Repeat 2 times – upon arrival and before you
leave the site.
5. Aspect
Use the compass to determine the aspect of the shore. Repeat 2 times.
6. Light Intensity
Observe the light intensity throughout the study time. We don’t have any instrument to
measure this, so you need to simply note down the cloud cover (no clouds at all, partially
cloudy, very cloudy).
B.
Transect Line and Shore Profile
Each group will erect a line transect and use it to examine the shore. Along the line transect
you will measure out stations that are located at 1.0 m intervals along the line.
You will make a map of the profile of the shore line by taking height measurements from the
point on the transect line station to the rock below (or above). You will use the tube provided
(put some water inside) as a level to determine the horizontal plane. This can then be used to
measure (with the meter stick) the sides of a right angled triangle as they intersect the transect
line. Later on you can use these measurements to calculate the angle of your transect line from
the horizontal. You will create a shore profile using the data that you have recorded. The
height measurements at each station can be plotted along the line that you will draw and then
the points will be connected to show the profile of the shore.
Remember to have a prepared table ready to record the height differences between the different
stations. If the station is lower than the transect line, this should be recorded as a negative
value, if it is above the line it should be recorded as a positive value.
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E.g. Table of transect line measurements, stations, their distance from the top shore and
their heights from the transect line as well as processed data to draw the shore profile. Shaded
columns would not be presented in a lab report (they’re for you!)
Horizontal
Length
(for angle)
Vertical
Length
(for
angle)
Angle
Station
Number
Distance
from top
shore
(m)
Height Height Scale
(cm)
(m)
diagram
Distances
from top
(cm)
0
0
0
-24
-0.24
1m x
3cm/m = 3
50.0
18.2
Tan Angle =
opposite/adjacent
1
2
0
1.0
3
2.0
-31
-0.31
6
4
3.0
+1
+0.01
9
5
4.0
-20
-0.20
12
6
5.0
-10
-0.10
15
= vert. h/horz. h
= 18.2/50.0
= 0.364
Tan angle =
0.364
Angle = 20.0˚
C.
Scale
diagram
Heights
(cm)
0
-0.24m
x3=0.72
-0.31m
x3=0.93
+0.01m
x3=
+0.03
-0.20m
x3=0.60
-0.10m
x3=0.30
Biotic Factors
The organisms are to be examined at each of the stations. The fauna and flora is identified,
abundance assessed and recorded.
Abundance Scale ACFOR SCALE
At each station along the transect place a quadrat. Looking inside the quadrat, determine how
abundant each species is using the following abundance scale:
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A = abundant C = Common F = frequent O = Occasional R = Rare N = absent
For plant species or ground cover use:
A
C
F
O
R
=
=
=
=
=
Abundant (greater than or equal to 30%)
Common (20-29%)
Frequent (10-19%)
Occasional (5-9%)
Rare (1-4%)
For barnacles, limpets, and periwinkles
A
C
F
O
R
=
=
=
=
=
25+
15-24
9-14
5-9
less than 5
For topshells, mussels, anemones, dogwhelks, crabs, isopods
A
C
F
O
R
=
=
=
=
=
15+
10-14
5-9
2-4
less than 2
Remember to either take a photograph of each of the species present along the shoreline and
to give each species either a name or a code.
E.g. Abundance for organisms found at transect stations
Station
1
2
3
4
5
Species
A
R
R
O
A
A
B
-R
F
C
C
D
F
C
F
R
E
R
O
6
7
F
A
R
A
A
A
The abundance data will be transferred onto the graphed shore profile as a kite diagram. Use
the following values for each of the scales on the graph paper. Each value should be equally
distributed along a separate line for each individual species.
A
C
F
O
R
=
=
=
=
=
10
8
6
4
2
Resources for transect lines and kite diagrams:
http://marinebiology.suite101.com/article.cfm/rocky_shore_transects
http://marinebiology.suite101.com/article.cfm/kite_diagrams
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2.
COMPARING TWO MANGROVE SWAMP COMMUNITIES
Within the Pranburi Forest Park, two distinct mangrove communities have been selected for this
comparative study. The first study area is close to the park entrance and is at the margin of the
swamp, closest to land. It is characterized by taller and more massive mangrove tree species.
The second study area is further down the boardwalk and is closer to where the swamp drains
into the estuary. The mangrove trees here are smaller and the water level is higher.
A.
Biotic Factors
Species Diversity Index and Simpson’s Index
Species diversity is a measure of the variety of different species in an area. If an area has high
species diversity, this means that there is a large number of species, and that a good number of
these species are present in reasonably large numbers. Low species diversity indicates that
there are relatively few species, often with two or three species present in much higher numbers
than the rest.
The Simpson Diversity Index can be calculated by:
Diversity (D) = N(N-1)
∑n(n-1)
Where N is the total number of organisms, of all species, found in the area and n is the number
of organisms of a particular species. The higher the value of D, the higher the diversity, so can
be used to compare different areas.
The Simpson’s Index can be calculated by:
Diversity (D) = ∑n(n-1)
N(N-1)
In this calculation, which is the inverse of the previous calculation, the value of D represents the
probability that two of the same species will be randomly selected from the organisms in the
community. 0 is the value that indicates the highest diversity while 1 indicates the lowest
diversity.
During succession the species diversity often increases with time. In the early stages, few
species will be adapted to what is often a harsh environment. Later the conditions become less
harsh and many more species are able to survive. The abiotic factors in an ecosystem affect
the species diversity. You should attempt to determine factors in this environment that affect
the species diversity.
B.
Sampling Techniques
In collecting species-abundance data, you should apply random sampling using the quadrat
method in each study area. You are not allowed to step out of the boardwalk, thus your quadrat
sampling should be done along the boardwalk by simply extending two metersticks one meter
apart. This will be your 1m x 1m quadrat. Randomly select 5 quadrat sampling stations in
each study area.
Count the number of each species that you observe within each quadrat. Take a lot of photos
to help you identify the organisms later. Collect soil and water samples to later observe for
microorganisms using a microscope. Do not disturb the sediment.
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Record the number of each individual species present in each quadrat.
E.g.
C.
Table 1. Number of Individual Organisms per Species in Each Quadrat.
Quadrat
Species
Number of Organisms
Number
1
A
12
B
3
C
4
D
4
E
1
Total
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Abiotic factors
1. Temperature
Measure the air temperature and the water temperature at your quadrat stations.
2. Total Dissolved Solids (levels of ion)
Collect 3 samples of water at each study area of the swamp. Make sure not to have any
trapped air at the top of the bottle. Put the lid on under water and dry off the bottle. Label
the bottle. You will test the total dissolved solids with a probe later.
3. pH levels
Measure the pH levels from the samples in #2 using the pH probes and/or the pH paper.
4. Dissolved Oxygen
Measure the dissolved oxygen in the samples from #2 (it is important that you take the
dissolved oxygen measurements first and then do the dissolved solids and pH afterwards).
5. Substrate
Observe and describe the bottom of the swamp. Take a photograph.
6. Water Quality Testing
Using the test kits provided, test for nitrates, phosphates, and coliform. Follow the
instructions on the kits. Collect any waste water in the waste bottle to take back to the hotel
with us. Do not dump chemicals into the environment.
7. Turbidity
Use the turbidity test kit to check the turbidity of the surface water. Do not stir up sediment
from the bottom but rather collect the water carefully.
8. Depth of Water
Use the meter stick to determine the depth of water in your quadrat.
9. Light Intensity
Observe the light intensity at each site.
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3.
INDIVIDUAL DESIGN INVESTIGATION AND DATA COLLECTION
During the course of the field trip, you should find the time to survey the beach ecology, in
addition to the rocky shore and mangrove investigations.






Determine your research question. This should be a testable question that will readily
lead you into an investigation. Studies that seek to determine the relationship between
some biotic factor and an abiotic factor work well.
You may choose any of the 3 habitats to study: rocky shore, sandy shore (either Dolphin
Bay or the beach adjacent to the rocky shore study area), or mangrove swamp.
Identify your variables and come up with a method that will provide you with sufficient
relevant data to process. You may consult any of the teachers. There will be a night
session on the second day allotted for consultation. Your design has to be approved by
any of the IB Biology teachers.
Identify the equipment and materials you will use. You will have to share materials with
your team members so you need to agree on a schedule.
Collect data on the third day.
Process your data (use graphs, calculations, statistical tests) and ultimately make a
conclusion. This part of the investigation will be done after the field trip and you will be
given about a month to prepare your reports.
**** For Those Individuals that Couldn’t Make the Trip****
1. You will use the information students collected to complete your own lab report. You will
have to collect your own background information about Pranburi to include in your
report.
2. You will use the information collected on the rocky shore by one of the students on the
ecology field trip. Using the information collected from the shore profile, draw a graph of
the rocky shore profile.
3. Using the abundance chart of the organisms collected; construct a kite diagram of the
different organisms that live on the rocky shores of Pranburi.
4. Use the abundance data of organisms collected to prepare Simpson’s Index calculations
and Simpson’s Diversity Index calculations.
5. Using the information collected at each station from the mangrove communities in the
estuary, calculate the species diversity using the species diversity index.
6. Use the data collected for the abiotic factors from the different stations to construct a
graph or graphs and make valid conclusions regarding the number and species diversity
at each station.
7. Write your own Design to investigate an aspect of ecology you have encountered during
the course of your study.
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