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Christian Halverson, Moruya High School, New South Wales

Nature of the inquiry problem

How do environmental pressures promote a change in species diversity and abundance? How can human activity impact on an ecosystem?

The inquiry problems sets out to investigate these questions by introducing a new concept known as limiting factors. A basic understanding of the need for nutrients, water, and mineral ions should be established in junior science, but this task adds depth to the knowledge helping students to appreciate light is limited by ocean depth and micronutrient iron is a major limiting factor in the Southern Ocean. Voyage researchers on board RV Investigator voyage IN2017_T01 are investigating the link between bushfires and iron levels in the Southern Ocean.

Suitable year levels and subject areas

Year 11 Biology Stage 6 Syllabus

Biological Diversity and Ecosystem Dynamics

Curriculum links

Biology Stage 6 Syllabus New South Wales

Effects of the Environment on Organisms


  • predict the effects of selection pressures on organisms in ecosystems, including: (ACSBL026, ACSBL090)
    • biotic factors
    • abiotic factors.

Population Dynamics


  • investigate and determine relationships between biotic and abiotic factors in an ecosystem, including: (ACSBL019)
    • the impact of abiotic factors (ACSBL021, ACSBL022, ACSBL025).

Future Ecosystems


  • investigate changes in past ecosystems that may inform our approach to the management of future ecosystems, including:
    • models that humans can use to predict future impacts on biodiversity (ACSBL029, ACSBL071).
Learning Objectives

Students learn to understand limiting factors in general with specific reference to light and iron in the ocean and the effect on marine algae. Students will also relate how CSIRO and the Marine National Facility conduct longer term research to inform how land management practices can have a profound effect on the Southern Ocean. Extension component brings the notion of geoengineering as a potential pathway to mitigate atmospheric Carbon Dioxide (CO2) by a biogenic process.

Student Learning Outcomes*

Students will access a variety of ICT resources to understand what a limiting factor is and how limiting factors play a role in the production of ocean algae which is the base of most marine ecosystems. Students will learn how researchers onboard RV Investigator use equipment to analyse atmospheric and ocean data to investigate where sources of iron in the Southern Ocean originate.


Research task

Assessment outcomes

No formal assessment associated with the task, but it could be used as formative assessment by staff to ensure that the concepts are understood.


Ecology and the Limiting Factors for Life(created by Christian Halverson) (2017) Copyright owned by Department of Education, New South Wales. Except as otherwise noted, this work is licenced under the Creative Commons Attribution 4.0 International Licence. To view a copy of this licence, visit

Download the lesson

Ecology and the Limiting-Factors for Life PDF (622 KB)

Ecology and the Limiting Factors for Life TXT (9 KB)

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