Teaching Sequence

Work through this resource material in the following sequence:

30 minutes	Part A. What changes affect mangrove and salt marsh ecosystems?
30 minutes	Part B. What adaptations of mangroves and salt marshes allow their survival?
30 minutes	Part C. How can conceptual models inform questions and predictions about ecosystems?
30 minutes	Part D. How can we formulate the best questions and hypotheses to help us maximise our assessments of mangrove health?

The Flipped Lesson

This lesson provides the opportunity for students to explore/build their current knowledge, attitudes and values about ecosystems. While working independently, students are to view the following videos and images on the Student Worksheet. Teachers will also gain insight from students’ responses which can be used to plan the following lesson about making predictions and forming questions as part of a MangroveWatch investigation.

To conduct this lesson, hand out or digitally distribute the Student Worksheet and invite students to work through it in the following order (also available in the Student Worksheet). Suggested answers are included below.

Part A. What changes affect mangrove and salt marsh ecosystems?

Students will:

discuss environmental changes that may cause variations in species
watch two video reports describing the causes and effects of change within ecosystems
predict the capacity of species to adapt to climate change

Part B. What adaptations of mangroves and salt marshes allow their survival?

Students will:

identify abiotic factors facing mangrove and salt marsh species
describe structural adaptations of mangrove and salt marsh plants

Part C. How can conceptual models inform questions and predictions about ecosystems?

Students will:

discuss the purpose of ecosystem conceptual models
brainstorm the processes as well as biotic and abiotic factors of mangrove ecosystems
discuss the mangrove ecosystem flow chart processes and elements
identify environmental drivers enabling the ecosystem to exist
clarify why mangroves are considered keystone species
list abiotic and biotic factors that could be measured
design a question for scientific investigation through MangroveWatch

Part D. How can we formulate the best questions and hypotheses to help us maximise our assessments of mangrove health?

Students will:

preview the Earthwatch video on the mangrove investigation
describe the purpose of the Earthwatch investigation
identify and list variables filmed as dependent, independent or controlled
describe the environmental and community benefits of Earthwatch

Suggested Answers

The answers below can be used to help you guide your students through this flipped lesson, and to assist with the assessment of student work.

Part A. What changes affect mangrove and salt marsh ecosystems?

Background Information: MangroveWatch focuses on collecting baseline data on mangrove ecosystems to determine change. This data is analysed to help MangroveWatch researchers understand and make predictions about the effects of storms, drought, climate change, floods, fire, land clearing and introduced species on these ecosystems. These change processes may create selective pressures causing variations in traits and possibly new species over time.

Students will watch two clips and answer a series of questions about these clips:

1. Watch the video “Our Estuaries” and describe research into the impacts of change - Our Estuaries (https://youtu.be/GoEMwhmt5n8)

Suggested answer: A team of scientists are collecting first-hand data on estuaries to determine the threats from climate change to these important environments.

2. Watch the ABC report about mangroves to describe climate change impacts - Mangrove death in northern Australia - ABC story (https://youtu.be/sfOLdCWoXDA)

Suggested answer: An unusually dry wet season of only one month of rain as well as elevated temperatures are thought to have caused the dieback of 10% of the mangroves in the Gulf of Carpentaria.

3. Explain why species may not adapt through Natural Selection to survive climate change.

Suggested answer: Scientists are concerned that the rate of change in climate and sea levels due to climate change may be occurring so rapidly that there is insufficient time for species to develop and pass on traits to survive these new environmental conditions.

Part B. What adaptations of mangroves and salt marshes allow their survival?

Background Information: Structural adaptations are physical features of an organism that help its survival and reproduction. Mangroves have adaptations to physical features - such as their leaves and roots - and their reproductive processes that help them to survive in soft unstable sediments that are low in oxygen and of varying salinity.

1. Why do Grey Mangroves (Avicennia marina) have aerial roots called pneumatophores?

Suggested answer: Mangroves grow in water-logged soils. Pneumatophores are vertical roots extending into the air that enable Avicennia marina to take in oxygen for respiration.

2. Why do pneumatophores have air spaces called aerenchyma?

Suggested answer: Aerenchyma are air spaces within the pneumatophores of Avicennia marina that allow for the uptake and storage of oxygen during low tide. They provide an internal pathway for oxygen transport.

3. Why do River Mangrove leaves often have salt on their surface?

Suggested answer: Salt can kill plants so mangroves need to extract freshwater from salty sea water and then get rid of the salt. Mangroves are able to block most of the salt at their roots via cellular processes such as active transport. Some species are able to excrete small amounts of salt via their leaves. The upper surface of the leaves of Aegiceras corniculatum are covered with very small salt glands that provide an additional way to remove salt from the plant. There is increasing evidence that leaf salt gland secretions on the leaf surface may help some mangrove species survive in arid environments by de-humidifying air and trapping dew. This process serves both as a way for leaves to conserve water and prevent water loss during photosynthesis and water on the leaf surface can be drawn into the plant through the leaves. Leaf water trapping via salt crystals on the leaf surface can account for up to 80% of plant water requirements during periods of low rainfall.

4. Why do mangroves have shallow, spreading roots?

Suggested answer: Shallow, widespread roots provide better support in soft, unstable sediment. This helps prevent the mangroves from toppling over or being swept away in high tides or during storm events.

5. Why do Grey Mangrove propagules float?

Suggested answer: Grey Mangroves are crypto-viviparous (bear live young) and when the fruit fall from the tree into the water they continue to germinate and float for several days. Eventually they may wash up onto a shoreline where the propagule becomes embedded into the sediment, and may begin to grow into a tree. Just over half of the world’s mangrove species are viviparous.

6. Why do salt marsh plants have leaves that are fleshy and succulent?

Suggested answer: Some salt marsh plants conserve water by storing salty water in fleshy leaves or stems. Storing salty water in the leaves and stems prevents water being lost from the plant at the roots into saline soils via osmosis.

Part C. How can conceptual models inform questions and predictions about ecosystems?

Background information: A conceptual model outlines a system or process, and the concepts that comprise that process, in order to help us understand how the bigger picture works. In this case, students will be focusing on a conceptual model of an ecosystem.

1. List some of the environmental drivers responsible for the mangrove ecosystem formation.

Suggested answer: The environmental drivers influencing the formation of mangroves are local climate, alternating tidal exchanges with salt water and currents within sheltered estuarine environments.

2. Name the process where non-living matter is converted into organic matter.

Suggested answer: Photosynthesis. Photosynthesis is the process used by plants, algae, and certain bacteria to harness energy from the sun and turn it into chemical energy that the plants can absorb.

3. Explain why mangrove trees are called a keystone species.

Suggested answer: A keystone species is a plant or animal species that plays a unique and crucial role in the functioning of an ecosystem. Mangrove trees play a critical role in how the ecosystem functions. Without the mangrove trees, the mangrove ecosystem would cease to exist.

4. List abiotic or non-living parts of the environment which could be measured.

Suggested answers: Sediment type and deposition of sediments; water movements caused by wind, tides and currents; soil nutrients; soil moisture; soil salinity; organic matter in soil.

5. List biotic or living parts of the environment which could be measured.

Suggested answer: Mangrove propagules embedded in sediment, species and abundance of: waterbirds, fish, invertebrates, types of mangroves and types of salt marsh plants.

6. Create a question about mangroves or salt marshes you could investigate by working scientifically through MangroveWatch.

Suggested answer: How does the type and number of mangrove species vary from the mean low tide level to the mean high tide level?

7. How does this model help you understand mangrove ecosystems?

Suggested answer: At student discretion.

Part D. How can we formulate the best questions and hypotheses to help us maximise our assessments of mangrove health?

Background information: Earthwatch is an international environmental organisation that conducts scientific field research with the help of volunteers. People from all around the world participate in Earthwatch programs by conducting field research with the support of scientists and professional researchers. In this way volunteers can meaningfully engage in real-world environmental research and action, and share what they have learnt with their networks upon returning home.

Students will watch a clip about an Earthwatch mangrove investigation and answer a series of questions relating to this clip:

James Cook University - Mangrove Watch (https://youtu.be/H9wWNcrWsgY)

1. Describe the purpose of the Earthwatch mangrove investigation.

Suggested answer: The Earthwatch and MangroveWatch program allows citizens to work alongside scientists to gather data about mangrove forest diversity, biomass and change over time.

2. Describe the environmental and community benefits of the Earthwatch and MangroveWatch program.

Suggested answers:
- Environmental benefits: Scientists will obtain baseline data about the effect of change over time and how this influences diversity of mangroves and their biomass (carbon stored). The new knowledge created by the MangroveWatch scientists will be applied to other mangrove ecosystems for their management and conservation.
- Community benefits: People participating in this program will feel they are taking real action to help biodiversity, will be inspired to share their learnings with their communities, and will be empowered to take more action.

3. List the variables discussed and demonstrated in the Earthwatch clip.

Suggested answers:
- Dependent variables (what is being measured);
- Height and girth of the mangrove trees; type and abundance of different mangrove species;
- Independent variables (what is going to be changed);
- Taking measurements and video recordings at different locations and using a GPS to record these locations;
- Controlled variables (what has to be kept the same/constant);
- Methods for measuring tree height and tree girth will be kept the same; the same procedures will be used for shoreline monitoring using video recording.

4. What factors identified in this clip could lead to more research in mangroves?

Suggested answers:
- Daintree mangroves compared to mangroves in other regions
- Highest diversity of mangroves
- Structural arrangements of mangroves
- Tidal systems
- Height and girth of trees
- Biomass and biomass accumulation
- Old data sets
- Change over time
- Carbon gain or loss

5. Can you use these factors to generate hypotheses or questions for further research in mangroves and mangrove ecosystems?

List three questions:

Suggested answers:
1. How does the type and number of mangroves vary from the mean low tide level to the mean high tide level?
2. Globally, which regions have experienced the greatest amount of biomass accumulation in their mangrove ecosystems over the past 10 years? Which have experienced the greatest decline?
3. Do some mangrove species absorb more carbon than other mangrove species? Do mangroves absorb more or less carbon than species found in rainforests or woodland ecosystems?

MangroveWatch - Identifying Variables

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