Middle School Students Explore Lake Tahoe’s Aquatic Food Web

What would happen if all the zooplankton were removed from Lake Tahoe?  More than fifty middle school students explored this and other compelling lake ecology questions during a food web activity at the Tahoe Environmental Research Center (TERC) in January. Working with TERC staff and Kevin Beals, a Curriculum Specialist at the Lawrence Hall of Science, students investigated the complicated interdependence of organisms in lakes.  They began by modeling scientific observations using an ‘I Wonder / I Notice / It Reminds Me Of’ framework to analyze 2D and 3D images of aquatic organisms like Daphnia and the non-native Mysis shrimp

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Student visitors at TERC engage in visual inquiry of lake organisms

Then students worked together to create a model of the Lake Tahoe aquatic food web.  Starting with the lake producers (algae and plants), each pair of students reasoned out where their assigned organisms reside in the web.  The end result was, like the actual Tahoe food web, quite complex.

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Kevin Beals, a Curriculum Specialist at the Lawrence Hall of Science, works with a group of middle school students to build a model of Lake Tahoe’s food web

Taking it further, the students made predictions about how the removal or addition of one organism in the ecosystem could have an enormous impact on the whole system.  Kevin presented examples of ecologic challenges that Lake Tahoe managers have faced in the past.  For instance in the 1960s, lake managers introduced Mysis shrimp to Lake Tahoe with the intention of increasing the fish population.  It turned out that the fish rarely ate the Mysis, but Mysis did eat Daphnia, a primary food source for Tahoe’s native fish population, resulting in the opposite effect as intended.  Students began to understand how even well-intentioned ecological interventions can have unexpected and sometimes negative consequences.

The students reported that they really enjoyed the Food Web activity because they were able to ‘actually do something’ and they liked thinking through the chain of cause and effect in the same way that scientists do.  For future iterations of the activity, we plan to integrate viewscopes and other 3D visualizations to further explore how 3D technology can be used to impact STEM engagement with and understanding of freshwater ecosystems.

In addition, many scientists, like this group at the University of Chicago use 3D (or higher dimension) food web models to better uncover the myriad connections between species and more accurately predict how ecosystems will respond to changes like species invasion or climate change.  Perhaps future versions of the Lake Tahoe food web activity could incorporate 3D lake food webs to test whether 3D models are more effective than 2D webs at fostering student understanding of freshwater ecology.

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