Is Your Sunscreen Hurting Oysters? Probably.

By Erika Zambello, based on an article by Madison Toonder.

Though still in high school, Madison Toonder is passionate about science, and recently used the scientific method to study oysters in the coastal environment near her Florida home.

“I discovered the importance of conservation at a young age,” she wrote in a new article for Voices for Biodiversity. “My interest in protecting oysters developed after visiting Busch Gardens in the summer of 2014, where I learned that worldwide populations are in decline due in part to pollution from fertilizer, fossil fuels, waste runoff and sunscreen.”

Oysters are socially and environmentally important. They are integral parts of local economies when they are harvested for food, and while they remain in the water one oyster can filter an astonishing fifty gallons per day.

As mentioned above, sunscreen can be dangerous for oysters. “[M]anufacturers are nanosizing sun protection ingredients such as zinc oxide and titanium dioxide,” she writes. As these microscopic particles enter the ocean, what effects might they have on oysters?

Madison designed a study to test how these sunscreens are harmful. Using bivalve mollusks from a local river, she placed them in three tanks. Keeping one as a control, she added nanosized zinc oxide sunblock to the second tank and chemical sunscreen in the other. She watched them for 21 days.

At the end of her experiment, the nanoparticles in the zinc oxide did in fact hurt the oysters, reducing their ability to filter water; the water became cloudier. Madison notes, “While the algae and phytoplankton were digested and excreted, the nanoparticles of zinc oxide remained in the system longer than the food. Therefore, my conclusion is that nanoparticles of zinc oxide remained in the oyster’s digestive tract and prevented filtration at capacity.”

The oysters in the chemical sunscreen tank simply died. The budding scientist reports: “The chemicals in the sunscreen infiltrated their systems and caused irreparable damage that led to their deaths.”

Though her results indicate the potentially unfortunate consequences of sunscreen on oysters, Madison ends on a hopeful note. “An easy way for you to make a difference is to use natural alternative, non-nanosized zinc oxide sunblock rather than micronized chemical spray sunscreen or nanosized sunblock.” The more we know, the more we can help save these selflessly helpful shellfish.

To learn more about her research, read Madison’s entire article on

Toonder_Bio_Image (2)Madison is a 10th grader at Stanford University Online High School in Florida. She aspires to be an exotic/marine animal veterinarian with a focus on conservation of endangered species. In the pursuit of this career, she conducts scientific research on the oyster, sea turtle, alligator and pangolin with scientists from across the world and competes in science fairs up to the national levelTwo years ago, she was named second in the nation in STEM mathematics by Broadcom Foundation for her environmental oyster data. She also serves on SeaWorld’s youth advisory council. In her free time, she regularly volunteers at a veterinary hospital, assisting in patient diagnosis/care and surgery. In addition, Madison interns at the Brevard Zoo as a conservation representative; she routinely handles exotic animals such as ball pythonsShe is constantly expanding the reach of her conservation message by speaking at numerous environmental events and writing conservation blogs. She has served as a panelist at Brevard Zoo’s Youth Environmental Summit and Florida Virtual School’s “Virtual Voice. Most recently, she was selected as keynote speaker for GTM NERR’s “Friends of the Reserve” event. 

bio 2Erika Zambello is a writer and photographer currently living on the Emerald Coast of Florida. She has a Master’s Degree in Environmental Management from the Duke Nicholas School of the Environment, where she specialized in Ecosystem Science and Conservation. She is also a National Geographic Young Explorer, completing four trips to the Maine North Woods in each of the four seasons, Fall 2015-Summer 2016.

In addition to acting as the sole blogger for the entire Florida State Park system, she is a regular contributor to the Duke Nicholas School, the Maine Sportsman, Bangor Daily News, and 10000 Birds. In the past she has written for The Conservation Fund, the Triangle Land Conservancy, Sarah P. Duke Gardens, BirdWatching Daily, and the Florida Sportsman. Finally, she is the founder and managing editor of the travel website One World, Two Feet, co-founder of TerraCommunications, as well as the co-managing editor for the award-winning online magazine Voices for Biodiversity.

Follow her daily adventures on Instagram, @a_day_in_the_landscape or

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Meet the Author
An online magazine connecting humans with the natural world to help all species survive and thrive together. Voices for Biodiversity shares the stories of eco-reporters from around the world, using the ancient human art of storytelling to connect people with each other, other species, and the natural world. Our goal is to connect the human animal with the global ecosystem.