Hanna Ryan Heitefuss
8th Grade, Long Beach Middle School
Lido Beach, NY
Investigating Saltwater Intrusion on the Development and Growth of Vigna radiata and Heart Modulation of Daphnia magna
Hanna studied how salt water might affect aquatic plants and organisms that depend on fresh water. She prepared five concentrations of salt and tested them on mung bean seeds and the crustacean Daphnia magna and showed that the Daphnia could be sensitive to salt in their water.
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Project Background
Living on Long Island, Hanna sees the beach as more than a vacation. “The beach isn’t just a place I visit but it’s a part of my routine, my community, and my identity.” She watched with concern “changes that affect my time spent at the beach such as rising water levels, and increased flooding,” she says. Hanna became especially worried about saltwater intrusion into freshwater areas near her home. She decided to find out how different amounts of salt in water could affect plant growth and aquatic organisms. Â
Tactics and Results
Hanna prepared solutions of salt and water at five different concentrations, from zero to 0.5 percent salt. Then she tested different organisms and how they might respond to the salt and water mix. She placed mung bean seeds (Vigna radiata) in dishes with different concentrations of salt, and measured how long they took to germinate. Hanna also looked at the effects of salt on Daphnia magna, a tiny freshwater crustacean. She transferred the Daphnia into different salt solutions for five minutes each, and measured their heart rate under a microscope for 60 seconds. While the mung beans did not show differences in their germination, higher concentrations of salt made the Daphnia’s tiny hearts beat fast — meaning their bodies were under stress. This could mean that freshwater organisms are sensitive to more salt in the water they call home.
Beyond the Project
For Hanna, environmental damage is personal. “Our island community faced devastation in the past with severe weather events such as Hurricane Sandy which brought major impacts on homes and property,” she says. “Living so close to a real-world problem makes me want to protect not only mine but all coastal regions in the future.” Hanna knows that sea level rise and extreme weather affect not just ecosystems, but the people who live in them. Hanna participates in local beach cleanups in her community during the summer, as well as being in environmental clubs. She also plays volleyball and sings.
