Minnamurra Lab

Aim: To construct a field graph to study the local ecosystem at the Minnamurra estuary involving abiotic factors, transects and abundance.

Method:
Measuring abiotic factors
1. Measure the elevation along the transect line in centimetres using an inclinometer in each quadrat.
2. Measure the soil temperature in degrees using a thermometer by placing it in the ground in the quadrat.
3. Measure the air temperature in degrees using a thermometer by holding it up in the air just above the ground in the quadrat.
4. Measure the wind speed in knots using an anemometer held up in the air in the quadrat.
5. Measure the soil moisture in the quadrat using a soil moisture probe. Soil moisture is represented in a percentage 1%-100% with 100%
being the maximum amount of moisture.
6. Measure the amount of sunlight in the quadrat using a lux meter.

Calculating the abundance of animals across the mangroves and salt marsh
1. Place a quadrat somewhere in the shoreward edge of the intertidal zone
2. Align the quadrat with a compass so that one side faces north and the other faces south.
3. Calculate the area of the quadrat in metres squared.
4. Calculate the abundance by first, finding the area of the quadrat in m2. Total number of individuals in each quadrat and the total number of quadrats. Average number of individuals per quadrat = total no. Individuals ÷ total no. Quadrats.
5. Estimation of abundance = Average no. Individuals per quadrat x Area of quadrat.

Abiotic Results: Quadrats
1
2
3
4
5
6
7
8
Elevation in Centimetres
144
145
149
153
147
145
142
138
Quadrats 9-16
146
131
131
146
185
177
180
195
Soil temperature in degrees Celsius
27.5

28.1
28
27.6
27.8
27.5
27.2
27.3
Quadrats 9-16
28.3
27.6
23.2
21.5
20.2
24.6
23.6
23.1
Wind speed in knots
0
1.9
0
0
0
0
0
4.9
Quadrats 9-16
0
0
0
0
0.9
0.5
0.4
1.4
Soil moisture 1-100
100
100
100
100
100
100
100
100
Quadrats 9-16
100
100
100
100
100
70
100
70
Light intensity
19500
18000
18800
14500
21000
20000
12000
12500
Quadrats 9-16
18000
18000
15000
15000
12000
12000
10000
10000

Discussion:
1. Describe the vegetation along the transect. Mention dominant species in each zone, patterns of distribution and comments on where zones merge.
In the first four quadrats, the salt-water couch is the most dominant species. It appears in quadrat three and four. The grey mangrove and the river mangrove are also in this zone. All these species are found in intertidal zones so this zone is the intertidal zone. In quadrats 5-8, the river mangrove is found in all quadrats and is the dominant species in this zone. Samphire was also found in quadrats 6 and 7, and salt-water couch in quadrat 8. In quadrats 9-12, the river mangrove is the most dominant but only appears in quadrat 11 and 12. There is no other species found other than the river mangrove in quadrats 9-12 suggesting a merge of zones in the next few quadrats. In the last four quadrats, the swamp she-oak is found in all four quadrats and is the most dominant species in this zone. A large amount of salt-water couch is also evident and also some seablite and grey mangrove.
She-oak is found above high tide and seablite is also found at the high tide of the intertidal zone suggesting that the zone has merged to above high tide.

2. Describe relationships between vegetation and the distribution of animals.
There was only one Bembicium in the whole transect and it was found in the eighth quadrat.
Quadrat 8 also had 20% river mangrove and 40% salt-water couch.

3. Describe changes in abiotic factors along the transect. Identify possible relationships between abiotic gradients and vegetation zonation.
The elevation between quadrats 12 and 13 rises greatly because of the zone change to above high tide. Because of this change in elevation the swamp she-oak is found in the last four quadrats of the transect because she-oaks are found in zones above high tide. In quadrats 6-8, the elevation decreases and the river mangroves population is increased. This may be caused because the mangroves may have access to water at the lower elevation. Also, the sunlight decreased dramatically from quadrat 6 to 7 and in quadrat 7, the river mangrove covers 75% of the quadrat.

4. To what extent can the pattern in vegetation be explained by past and present human activity and related biotic
factors.
The vegetation has experienced some terrible consequences as a result of human activity; for example, the track made by people stepping on the vegetation. With people continually walking on the soil and vegetation, the vegetation will not be able to continue growing or to sustain a healthy life. For the plants relying on water, the pollution of the estuary caused by boats and rubbish can affect the growth and survival of them greatly. Also the bridge built through the vegetation, killing most of it has had a massive impact on the survival of the vegetation.

5. Discuss the validity of your results that describe the zonation from mangroves to saltmarsh.
The results for the zonation of mangroves are valid for many reasons.
Firstly, the elevation from quadrat 12 to 13 shows the zone shift from intertidal to above high tide, and from quadrat 13 onwards, the swamp she-oak is most dominant, which is even more evidence to show that it is in fact above high tide. There are also no mangroves past quadrat 13, as they reside in the intertidal zone. The mangroves are all over between quadrats 1-12, and with 100% soil moisture in all of those quadrats, that that is in fact the intertidal zone. The soil moisture varies in the last 4 quadrats since it is no longer in the intertidal
zone.