Mangrove Ecosystems

Module 3 Biological Diversity, Module 4 Ecosystems Dynamics

 

 

 

 

 

 

 

Welcome!

The information on these pages will help teachers and students undertaking the Year 11 Biology program Mangrove Ecosystems.

This program can be completed as fieldwork or combined with pre and post visit research to complete a Depth Study.

The Year 11 Biology program Mangrove Ecosystems will provide students with an opportunity to learn about the dynamic nature of mangrove ecosystems, through research and fieldwork, to help answer the inquiry question:

How do humans impact on the mangrove ecosystem at Bobbin Head?

The program includes fieldwork components for aspects of Module 3 Biological Diversity and Module 4 Ecosystems Dynamics and is made up of three components:

1. Pre visit research
2. Fieldwork (at Bobbin Head)
3. Post visit and Depth Study (optional)

As indicated, the program can contribute up to 12 hours for those wishing to use this to complete a depth study.

Teacher Programming Outline

Download the student fieldwork booklet (please print a copy for each student)

HSC Biology Syllabus

Mangrove Features

Questions that will guide (but not limited to) an understanding of mangrove ecosystems include:

  • what are mangrove ecosystems?
  • where are they located?
  • what are the biotic and abiotic features?
  • what are the importance of mangroves to humans?

The following resources will assist teachers to develop a program of learning prior to the field work.

  1. Ecosystems Dynamics, Functioning and Resilience Video

DPI Mangrove Factsheet

Field Guide to the Mangroves of Queensland

Guide to the mangroves of Singapore

Plant Adaptations

Human Impacts

Questions that will guide (but not limited to) an understanding of mangrove ecosystems include:

  • what are the importance of mangroves to Aboriginal people?
  • what are some of the past and current human impacts on mangroves?
  • what are the future threats to mangrove ecosystems?

Resources

Human Influences on Mangroves

Impacts on Mangroves from Sea Level Rise

WWF Global: Threats to Mangrove Forests

Planning Investigations

Questions that will guide (but not limited to) an understanding of the field study site include:

    • where is Bobbin Head located?
    • what are the features and human uses of Bobbin Head?
    • how has Bobbin Head changed over time?

The following resources will assist teachers to develop a program of learning prior to the field work.

Interactive Resources

Google Map

Drone Footage at Bobbin Head

Further Resources

Map of Cowan Creek Mangroves

National Parks website

Historic Images of Bobbin Head (in google docs – open through gsuite)

Reading Tide Times for the visit

Risk Assessment

Measuring Biotics

Questions that will guide (but not limited to) an understanding of the field study techniques include:

    • what techniques can be used to sample population abundance and distribution?
    • what is the most appropriate technique for studying mangroves and crabs?

A population is a group of similar organisms living in a given area as a time. Populations can never be 100% accurately counted; this is because of the difficulty of describing in detail large areas. Also it would be too time-consuming and damaging to the environment. Populations are estimated using sampling techniques. These make an estimate, which is roughly accurate of the population.

Distribution

Distribution refers to the region where an organism is found. A transect will be used to measure distribution for the mangrove study at Bobbin Head.

Abundance

Abundance refers to the number of individuals in the area. A 1 metre x 1 metre quadrant will be used to measure abundance during the program.

Links

Mangrove virtual excursion

Mangrove Study Documentary Part 1

Mangrove Study Documentary Part 2

Study on correlation between crab holes and abundance

Study on Grey Mangroves distribution and abiotic and biotic factors

Measuring Abiotics

Questions that will guide (but not limited to) an understanding of abiotic factors include:

    • what are abiotic factors?
    • what are some of the abiotic factors of mangrove ecosystems ?
    • how do we measure these abiotic factors?

The following abiotic factors may be measured during the fieldwork inquiry. Please visit the Gibberagong youtube channel for instructional videos for each abiotic procedure.

Soil Moisture

Soil moisture is a limiting factor in the growth of plants. Soil moisture that is a consequence of tidal influence is a critical factor in determining the distribution of mangrove and saltmarsh species.

Water logged soils cause a slow rate of oxygen and nutrient replacement, as a result the soils surrounding mangroves are often low in oxygen and nutrients. While salt within tidal waters is toxic to many plant species.

Equipment – No equipment

Procedure

  1. Pick-up a sample of soil in your hand from the sampling site.
  2. Feel the soil and mix it around in your hand.
  3. Using a scale of 1-10, estimate the soil moisture. 1 being the driest, 10 being dripping wet.
  4. Record the result on your field worksheet.
Soil Temperature

Soil temperature is critical in the germination of seeds and the rate and duration of plant growth

Equipment – probe thermometer

Procedure

  1. Remove cover from thermometer probe
  2. Insert the thermometer probe into the soil
  3. Turn on the thermometer
  4. Measure and record in degrees Celsius
  5. Repeat the procedure three times and record the average
Air Temperature

Air temperature is a limiting factor upon plant and animal species. None more so than mangroves. In the cooler temperate southern locations of Australia only two species of mangroves occur, the grey mangrove and the river mangrove. While in the warmer northern parts of Australia the number of mangrove species is close to thirty.

Air humidity is important for the sustainability of mangrove forest ecosystems. Air humidity influence the amount of mangrove litter in forms of leaves, twigs and other biomass, it is a food source for the aquatic biota and the nutrients released determining productivity of waters. Logging and opening of mangrove forests impacted on decreasing air humidity, increasing evaporation and encourages the occurrence of soil moisture deficit and drought (Hatcher. et al., 2012; Yan. et al., 2007)

kestrel

Equipment – thermometer (temperature) and hygrometer (humidity) – one piece of equipment will measure both

Procedure

  1. Locate the Kestrel weather meter
  2. Take off the cover
  3. Hold the middle button to turn on
  4. Scroll right until you find dEC (degrees celsius)
  5. Hold the Kestrel above your site, away from your body
  6. When the reading stabilises (stops going up or down), record your measurement in degrees celsius
  7. Carefully replace the case and return your equipment
Light Intensity

Like other plants mangroves convert sunlight energy into organic matter through the process of photosynthesis. Sunlight intensity and duration influences the levels of photosynthetic productivity.

lightmeter

Equipment – A Light Meter (unit of measurement = lux)

Procedure

  1. Remove the cover
  2. Hold the sensor 1m above the ground over the quadrat
  3. Turn on, record reading
  4. Multiply the result if necessary
  5. Repeat 3 times to calculate an average
  6. Turn off and return to pouch
Wind speed

Wind speed and direction affects the temperature and humidity of an area. Wind affects creates small waves in the estuarine environment and also contributes to the dispersal of propagules in water currents.

kestrel

Equipment – anemometer (part of a kestrel instrument)

Procedure

  1. Locate the Kestrel weather meter
  2. Take off the cover
  3. Hold the middle button to turn on
  4. Scroll right until you find km/h AVG (Average Wind Speed)
  5. Hold the Kestrel for 1 minute at your site, away from your body
  6. After 1 minute record your measurement in km/h
  7. Carefully replace the case and return your equipment

Depth Study

For their depth study, students can:

EITHER

Investigate “How predicted changes to the climate will affect the mangroves at Bobbin Head”.

To answer this students will need to research effects of climate change and combine this with what they have learnt during their field work and further research.

This could involve:

– a community education campaign outlining risks to mangroves

– designing a long term scientific study (over 10 years) looking at the impact of rising sea levels on the plants and animals at a site

OR

further investigate or commence a particular inquiry or area of interest inspired or prompted by the original investigation.

Climate Change resources

High tide predictor for Sydney

Click on the link below and type in Bobbin Head picnic ground to view the effect of sea level rise on the picnic area and mangroves at Bobbin Head. Compare the current day highest tide with the video below from a recent king tide

Coastal Risk Australia

Timelapse of king tides at Bobbin Head