'Sea Sawdust' (Trichodesmium) and Biogeochemical Cycling

Greta Creed, North Lakes State College, Queensland

This inquiry problem allows students to improve their understandings of the roles of plankton (e.g. Trichodesmium) in marine food webs, and their interactions with nutrient availability/biogeochemical cycling in the marine environment.

The series of resources are suitable for Year 9 Science (Biological sciences), Year 10 Science (Earth Science) and Year 11 Earth & Environmental Science. The resources can be utilised as stand-alone lessons, or as a full sequence of five lessons.

Year 9 Science

Biological sciences sub-strand

Year 10 Science

Earth Science sub-strand

Senior Earth and Environmental Science

Unit 2: Earth processes - energy transfers and transformations 

Australian Curriculum (ACARA) Year 9 Science: Biological sciences sub-strand

Science Understanding

• Ecosystems consist of communities of interdependent organisms and abiotic components of the environment; matter and energy flow through these systems (ACSSU176).

Science as a Human Endeavour (SHE)

• Advances in scientific understanding often rely on technological advances and are often linked to scientific discoveries (ACSHE158).

Science inquiry Skills

(Processing and analysing data and information)

• Analyse patterns and trends in data, including describing relationships between variables and identifying inconsistencies (ACSIS169).
• Use knowledge of scientific concepts to draw conclusions that are consistent with evidence (ACSIS170).

(Evaluating)

• Evaluate conclusions, including identifying sources of uncertainty and possible alternative explanations, and describe specific ways to improve the quality of the data (ACSIS171).

Cross Curriculum Priority - Sustainability

Australian Curriculum (ACARA) Year 10 Science: Earth Science sub-strand

Science Understanding

• Global systems, including the carbon cycle, rely on interactions involving the biosphere, lithosphere, hydrosphere and atmosphere (ACSSU189).

Science as a Human Endeavour (SHE)

• Advances in scientific understanding often rely on technological advances and are often linked to scientific discoveries (ACSHE194).

Science inquiry Skills

(Processing and analysing data and information)

• Analyse patterns and trends in data, including describing relationships between variables and identifying inconsistencies (ACSIS203).
• Use knowledge of scientific concepts to draw conclusions that are consistent with evidence (ACSIS204).

(Evaluating)

• Evaluate conclusions, including identifying sources of uncertainty and possible alternative explanations, and describe specific ways to improve the quality of the data (ACSIS205).

Cross Curriculum Priority - Sustainability

Australian Curriculum (ACARA) Earth and Environmental Science

Unit 2: Earth processes – energy transfers and transformations

Science Understanding

• Biogeochemical cycling of matter, including nitrogen and phosphorus, involves the transfer and transformation of energy between the biosphere, geosphere, atmosphere and hydrosphere (ACSES055).

Science Inquiry Skills

• Represent data in meaningful and useful ways; organise and analyse data to identify trends, patterns and relationships; qualitatively describe sources of measurement error, and uncertainty and limitations in data; and select, synthesise and use evidence to make and justify conclusions (ACSES033).

Science as a Human Endeavour

• Advances in science understanding in one field can influence other areas of science, technology and engineering (ACSES039).

Students will explore the features of marine food webs, including the role of phytoplankton (with a focus on Trichodesmium), and consider how microorganisms contribute critically to marine food webs. The role of nutrient availability in the marine environment will also be considered.

Lesson 1: Marine Food Web

Students should be able to:

• recognise feeding relationships between organisms in a Tasmanian marine environment
• organise marine organisms into their correct trophic levels
• construct a detailed food web.

Resources:

• Lesson Plan 1 – Marine Food Web – Tasmania
• Marine Food Web Species Info Sheets (Tasmania NPWS)
• Marine Organism Ecology Worksheet
• Marine Food Web Diagram (Tasmania NPWS)
• Marine Food Web Answers (Tasmania NPWS)

Lesson 2: Plankton

Students should be able to:

• distinguish between phytoplankton and zooplankton in the marine environment

• recognise the vital roles of phytoplankton and zooplankton in the marine food web
• identify features of the range of organisms known as phytoplankton.

Resources:

• Lesson Plan 2 – Plankton
• Introduction to Plankton Worksheet
• What are Phytoplankton Worksheet
• Plankton Wordsearch.

Lesson 3: Types of Phytoplankton

Students should be able to:

• identify different types of phytoplankton (e.g. diatoms, dinoflagellates)
• recognise the extent and significance of phytoplankton blooms
• understand the role of satellite and other technologies in monitoring phytoplankton blooms.

Resources

• Lesson Plan 3 – Types of Phytoplankton
• PowerPoint – Types of Phytoplankton
• Types of Phytoplankton Worksheet.

Lesson 4: Studying Phytoplankton

Students should be able to:

• identify a range of technologies available to scientists for studying phytoplankton (and other marine environment issues)
• understand the role of citizen science in supplementing and extending scientific knowledge
• apply tools available in ‘Atlas of Living Australia’ to explore the distribution of phytoplankton (Trichodesmium and Noctiluca) in Australian waters.

Resources:

• Lesson Plan 4 – Studying Phytoplankton
• PowerPoint – Studying Phytoplankton
• Studying Phytoplankton Worksheet.

Lesson 5 – Trichodesmium and CSIRO Data

Students should be able to:

• utilise hydrochemistry data from RV Investigator Voyage IN2019_T02 to identify trends in temperature, fluorescence (as an indicator of chlorophyll-a) and phosphate concentration
• compare and contrast sampling techniques and data obtained at two sampling (deployment) sites
• analyse data to make links between biogeochemical factors in the marine environment.

Resources

• Lesson Plan 5 – Trichodesmium and CSIRO data
• Trichodesmium Fact Sheet
• RV Investigator and Trichodesmium Worksheet.

Series of lesson plans with a range of resources including:

• retrieval chart

• Powerpoint and worksheet

• data analysis activity.

Formative assessment - data analysis task.

This task can be used in preparation for summative assessment of both Science Understanding and Science Inquiry Skills standards.

A range of audio-visual links are available in this resource. The Atlas of Living Australia provides data for the occurrence of Trichodesmium.