FIELD TRIP!!!! Flashcards
Human impact on mangroves
- Ships in marina can pollute water with oil and litter
- Cars can cause pollution in the form of brake dust, oil drips, roadkill
- Recreational use of Bobbin Head: deforestation to create parkland, building of toilets cause waste pollution, cafe creates litter
- Seawall prevents mangrove growth
- Discarded fishing nets entangle seabirds
Threats to mangroves in Australia
- Coastline development e.g. land reclamation
- Erosion of shorelines after heavy rain
- Marine oil pollution from sewage systems
- Climate change
- Disturbance events e.g. cyclones, pests
- Human activity
Climate change impact on mangroves
Increase
- Water temperature, acidity, level
- Average air temperature
- Soil salinity
These changes can cause abiotic factors to fall outside the optimal range of mangroves, damaging mangrove health and survival.
Mangrove adaptations
Saline environment, anaerobic soil, tidal inundation
Saline environment
- River + Grey: salt excretion
- Grey: salt exclusion
Anaerobic soil
- Grey: pneumatophores
- River: cells around base of tree helps gas exchange
Tidal inundation:
- Grey: viviparous seeds pre-germinate while still on tree so it can start growing right away when it falls to the ground → increase chance of surviving inundation as a seedling
- River: pre-germination, hooked seeds latch onto soil → increase chance of surviving inundation as a seedling
Grey/River mangroves comparison
- Grey mangroves bigger, more tree-like
- River mangroves more shrub-like
- Grey mangroves have pointy leaves + pneumatophores
Crab adaptations
Structural, behavioural, physiological
Structural:
- Semaphores have stalked eyes → increase spatial vision, allowing them to detect potential danger more easily
- Red-fingered crabs have a hard exoskeleton → stores water, which is flushed over their gills so they can breathe out of water
Phsyiological:
- Can breathe above and below water → able to survive at high and low tide
Behavioural:
- Move sideways → quicker movement due to longitudinal body
- Hiding in burrows → evade predators
3 marks
Draw a labelled diagram of a semaphore crab
4 marks:
Assess the [usefulness/validity/reliability] of the investigation you carried out to examine the distribution of crabs across the intertidal zone
Impact of climate change on built features
Erosion of sea walls, impacting ecosystems (grass dying from salt)
Damage to wooden structures and other infrastructure
Crab distribution investigation
Trend: decreasing further from the shoreline
Validity:
+ tests aim, correct equipment
- did not control dependent variable (size of crab hole)
Accuracy:
+ Average of multiple counts, reducing human error
- Equipment could be more accurate (photograph, ruler)
- Conducted only one transect
Reliability:
+ Multiple testings with similar results
Vegetation distribution investigation
Higher salinity of soil (conductivity) due to lower gradient: river mangroves
Lower salinity due to higher gradient: swamp oak and creeping brookweed
salinity impacted by tidal indunation (from topography)
Validity:
- Limited dependent variables (only three types of plants; narrow scope that doesn’t entirely answer the question). Also did not control the belt
Reliability
+ Corroborated by other groups
- However does not span the entire forest
Accuracy
+ Easy identification of plants
- Could use more precise equipment e.g. belt or quadrats
Water salinity test
Method and Significance
Method:
1. Place a drop of water sample onto the refracometer glass
2. Press down the cover to flatten the water sample
3. Look through the eye piece
4. Identify the % of salinity in the water using the line between blue and white on the screen
5. Repeat 3x and calculate the average
Significance:
- Plants have optimal ranges for salinity in which they thrive best. Variations too far from this range can cause a plant to sicken and die.
Water pH test
Method and Significance
Method:
1. Tear one strip from the pH testing book
2. Return the rest of the strips to the box immediately
3. Dip the strip into the water sample for ~10 seconds
4. Compare the colour of the strip to the colours on the pH chart
5. Repeat 3x and calculate the average
Significance:
- Plants have an optimal pH range in which they thrive best. Variations too far from this optimal range (when water becomes too acidic or basic) can result in the plant sickening and dying.
Water temperature test
Method and Significance
Method:
2. 1. Place water thermometer in sample immediately after collecting the sample
2. Wait for 30 seconds
3. Read the result from the scale of the thermometer
4. Repeat 3x and calculate the average
Significance:
- Plants have optimal temperature range
Turbidity test
Method and Significance
Method:
1. Collect a sample of water in a bottle
2. Pour small increments of the sample into a turbidity tube
3. Stop every 5-10cm and look through the hole at the top of the tube. If line markings at the bottom are still visible, keep pouring small amounts until lines stop being visible
4. Read the turbidity from the scale on the side of the tube. (NTUs).
5. Repeat 3x and calculate the average
Significance:
- Indicates water quality. Less turbid water is cleaner. If the water is very turbid, it means it has high levels of sediment, which can be harmful to mangroves
Soil Texture test
Method and Significance
- Collect a small handful of soil
- Add adequate water to create a ball. If you cannot make a ball, the soil is very sandy
- Feel the ball for its texture. If it is gritty = sandy; silky = silty; sticky = clay
- Reroll the ball, then gently press to make a ribbon. Short ribbon = loam; longer ribbon = more clay
- Repeat 3x and calculate the average
Significance:
- Plants have an optimum range of clay content in soil
Soil pH test
Method and Significance
Method:
1. Collect a soil sample from the site and place on a plate
2. Add 2-4 drops of indicator solution
3. Sprinkly barium sulphate powder over the sample
4. Compare the colour of the sample to the pH chart
5. Repeat 3x and calculate the average
Significance:
- Plants have an optimum range of soil pH in which they thrive best.
Soil temperature test
Method and Significance
Method:
1. Insert thermometre probe into the soil
2. Turn on the thermometre
3. Record the degrees C
4. Repeat 3x and calculate the average
Significance:
- Plants have an optimum soil temperature range
Light intensity test
Method and Significance
Method:
1. Hold the sensor 1m above the ground over the quadrat
2. Turn on and record the reading (Lux)
3. Repeat 3x and calculate average
Significance:
- Plants have an optimum range of light intensity
Humidity test
Method and Significance
Method:
1. Change the mode of Kestrel to relative humidity setting
2. Turn on device
3. Hold Kestrel above the quadrat, away from body
4. Record the reading as % when it stabilises
5. Repeat 3x and calculate the average
Significance:
- Plants have an optimal humidity range
Air temperature test
Method and Significance
Method:
1. Change the Kestrel mode to degrees C setting
2. Hold the Kestrel over the quadrat away from body
3. Record the reading in degrees C when reading stabilises
4. Repeat 3x and calculate average
Significance:
- Plants have an optimal range of air temperature
Parasitism in mangrove ecosystem
Mistletoe hanging off mangroves, stealing water and nutrients from the tree
Predation in mangrove ecosystem
Herons eat crabs
Mutualism in mangrove ecosystem
Crabs dig holes around mangroves and eat leaf litter → soil is aerated and crabs gain nutrients
Competition in mangrove ecosystem
Semaphores and red-fingered crabs use the same holes and eat in the same area → competing for food and territory
Commensalism in mangrove ecosystem
Oysters attach to mangrove roots → oysters protected from getting swept away by the tide
