Turtles: Impact of climate change on Flatback turtle populations

Sand temperature is important for turtles as the sex of hatchling turtles is determined by the temperature of the sand where the eggs incubate. Warmer temperatures will translate into more females and colder temperatures into more males. The temperature at which half of the eggs are male and half are female is called the pivotal temperature. For flatback turtles the pivotal temperature is around 28 ˚C. Scientists have placed temperature-logging equipment at flatback turtle nesting beaches across Western Australia.

The lesson follows an inquiry process in which students use a dataset to answer relevant questions about the turtle population. They consider how to analyse and display the data in order to effectively examine the impact of rising global temperatures on flatback turtle populations.

This lesson was created and developed in partnership with Pawsey Supercomputing Centre and Western Australian Marine Science Institution (WAMSI) Kimberley Marine Research Program. Turtle data was sourced from the WAMSI project, which is funded by the Western Australian State Government and research partners. Data is licensed under the Creative Commons BY-NC-SA 2.5 AU licence.

• Use relevant techniques to clean up data (eg remove blank rows).
• Save, store and use CSV files.
• Use spreadsheeting software to sort and filter data, use conditional formatting, Count If function, average function, to help answer inquiry questions
• Visualise data using mapping software such as Google Maps, using latitude and longitude data
• Analyse data and look for patterns.
• Create graphs such as a bar graph to present data.
• Select the most suitable graphing format to visualise and present data.
• Use higher order thinking skills (interpreting, analysing, inferring, summarising and evaluating).

Step 1

Use a relevant hook to engage students to discover more about marine turtles in particular flatback turtles.

• Use a quiz to stimulate interest in marine turtles and discussion of some key concepts.
• Use this 3D model of a flatback turtle to introduce the species. How is it similar and different to other turtle species
• A scenario could be introduced to encourage students to consider a range of issues and concerns to explore the impact of climate change. In the student task we have used the scenario: What happens to flatback turtles if the global temperature rises by 1.5°C, 2°C or more? Students could brainstorm potential issues.

Step 2

Briefly discuss students’ knowledge or experiences of climate change and what they know in particular about the impact of climate change on turtle populations. The sex of turtle hatchlings is determined by the temperature of the sand. Introduce the concept of pivotal temperature – the nest temperature at which 50% of hatchling turtles are male and 50% are female.

Step 3

Information about the datasets provided as Excel files for six sites:

• Nesting site 1: Logger 11011631 was deployed at Eco Beach (-18.27059, 122.16515). The logger is programmed to measure temperature every hour. It was deployed in the sand on 21 November 2016 and recorded data until 2 December 2018. Statistical guidance is provided.
• Nesting site 2: Logger 11023114 was deployed at 80 Mile Beach (-19.599209, 121.023961). The logger is programmed to measure temperature every hour. It was deployed in the sand on 14 November 2016 and recorded data until 13 July 2018.
• Nesting site 3: Logger 11011630 was deployed at Cape Domett (-14.79849, 128.415512). The logger is programmed to measure temperature every hour. It was deployed in the sand on 28 November 2017 and recorded data until 5 August 2018. Statistical guidance is provided.
• Nesting site 4: Logger 11023106 was deployed at Shark bay (-25.75716667, 113.6649167). The logger is programmed to measure temperature every hour. It was deployed in the sand on 3 January 2017 and recorded data until 8 January 2018.
• Nesting site 5: Logger 20213219 was deployed at Delambre Island (-20.46485894, 117.07438). The logger is programmed to measure temperature every hour. It was deployed in the sand on 26 November 2017 and recorded data until 23 November 2018.
• Nesting site 6: Logger 11000809 was deployed on Thevenard Island (-21.45675, 114.9886). It was programmed to measure temperature every hour. It was deployed in the sand on 9 December 2017 and recorded data until 15 November 2018.

Step 4

Depending on your students’ skills and familiarity with spreadsheeting software, such as Excel, Numbers and Google Sheets, you may decide to scaffold their introduction to the dataset or let them explore the dataset based on a question of interest.

Step 5

Use the Flatback turtle: Student task presentation slide deck, which provides a guide to students’ inquiry.

Step 7

Start by using conditional formatting to highlight the times the data goes outside the viable range. We want to know how much of the time the temperature is outside the viable range, and how much of the time the nest temperature will produce only males, or only females. As a class, discuss how best to display this data. One technique is to use conditional formatting.

1. Start with a line graph to show the change in temperature over time.
   

   

2. Now add in a line to show the 33°C maximum viable temperature. The simplest way to do this is to create a column of all 33s, as long as the column of temperatures, and then graph the two columns together as line graphs.
   

Step 8

Discuss setting appropriate labels for both of the lines as well as a meaningful title for the graph as a whole. Note that the simplest way to label the lines well is to change the heading labels for those columns in the spreadsheet.

Step 9

Ask students: What kind of graphs might you use to show the amount of time hatchlings will be: non-viable, male only, a mix of male and female, and female only?

Discuss as a class what you are trying to convey with this graph, and what the best type of graph would be to show this. Student may suggest a pie chart (circle chart), used for showing data as a percentage. For this exercise compare the same data presented as a bar chart and a pie chart and discuss the benefits and limitations of each.

As with all forms of communication, the important questions are: What are you trying to say? and What do you want the reader to understand from this graph?

As a class, discuss labelling of the charts and how this helps understanding. Make sure the students’ charts have titles, labels on each of the parts of the graph and legends. Also discuss how the big variations in values (for example the limited values for ‘males only’ in the Cape Domett data) make some of the sections of the chart difficult to read.

Step 10

Step 11

Ask the class groups for each nesting site to construct graphs that show:

• What percentage of time is the sand at a viable temperature for flatback turtle hatchlings?
• What percentage of time is the sand at, or close to, the pivotal temperature?
• When is the most suitable month or months for turtles to nest at the particular location?

Step 12

Provide an opportunity for groups to share their results so that each group can compare results and graphs for both nesting sites. Discuss different ways the data has been represented, considering the advantages and disadvantages of each technique.

Step 13

Apply what students have found

Using the results and graphs, students highlight the turtles’ plight, and the effect of a 2°C increase in global temperature. They can create an infographic, video or slide presentation to inform or persuade the public to care more about climate change.

Design a digital solution

Acquire data

Acquiring data is how we collect and access data from a variety of sources. Students can generate data of various types through their own experiments and investigations.

Store data

Record data in a format that allows it to be easily accessed or obtained. Students can describe how the data they have acquired can be stored in different ways using different representations and/or software. It is important to select the most suitable representation.

Organise data

Organising data relates to the ways we order, sort and arrange data to assist us with interpretation in different contexts.

Interpret data

Use data and its characteristics, properties and patterns to form a conclusion or derive meaning from it. Students can work with data that requires some simple processing using software. This could be in the form of simple spreadsheet calculations or using data in code. Students draw conclusions about the data as a result of this processing.

• Flatback turtle: Student task presentation slide deck
• Turtle quiz

Datasets

• Logger turtle data - Eco Beach (xlsx file)
• Logger turtle data - 80 mile beach (xlsx file)
• Logger turtle data - Shark Bay (xlsx file)
• Logger turtle data - Delambre Island (xlsx file)
• Logger turtle data - Cape Domett (xlsx file)
• Logger turtle data - Thevenard (xlsx file)

Flatback turtle information

• Flatback turtle (Natator depressus)
• What do sea turtles eat? Unfortunately, plastic bags

Video tutorials (spreadsheeting tips)

• Graphing and mean, median and mode
• Using the average formula