NetLogo – modeling effects of ocean acidification on fish (modeling learning activity)

Before you begin…

  • Ensure you have a strong understanding of systems and models by reading the background information page, if you haven’t yet.
  • You will need a pencil and paper as you work through this activity. You have the option of printing this webpage or recording your findings in a notebook.

Background: Ocean acidification and its impacts

As the issue of ocean acidification came to light, many scientists began to research what the result of more acidic oceans might be. We now know, for example, that lower pH caused by carbon dioxide makes it harder for shelled organisms to build shells, negatively affects the nervous systems of some fish, and can stimulate growth of aquatic plants. It turns out that elevated levels of CO2 also affect small reef fish. In a comprehensive article Munday et al. describe the “dramatic effect” of both elevated carbon dioxide concentrations and rising temperatures on “a wide range of behaviors and sensory responses” in various tropical fishes.

We’re going to use a specific study by Munday et al., “Replenishment of fish populations is threatened by ocean acidification” (PNAS, 2010) to build a model of how ocean acidification could affect clownfish-predator interactions.


Building the Model

The study shows that more acidic water will affect clownfish, but how will changing prey populations affect predators? Unless we want to build some really big tanks to observe the whole ecosystem, the only way to answer this question is through modeling. Let’s build a model to show us how changing CO2 concentrations effect the relationship between clownish and their predators.

Before we start, we will need to download NetLogo, a free to use tool to create models. The concepts of NetLogo are very similar to Stella Online, but you can reference the NetLogo Systems Dynamics instructions manual for any questions


Gaining Insight, 2020. More information.

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