Sixth grader's lionfish discovery blows ecologists out of the water

Lauren Arrington proved that lionfish can survive in less salty water than scientists previously understood.

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With few predators, voracious appetites and swift reproduction cycles, invasive lionfish from the Indo-Pacific pose a severe threat to indigenous marine life in the Atlantic ocean. But while researchers continue to hunt for a solution to the Caribbean lionfish invasion, 12-year-old Lauren Arrington asked a different question — could lionfish travel up rivers and wreak havoc on freshwater environments as well?

Arrington, now 13, told NPR, "Scientists were doing plenty of tests on them, but they just always assumed they were in the ocean. So I was like, 'Well, hey guys, what about the river?' "

Living in Jupiter, Florida, Arrington had previously spotted lionfish while snorkeling and fishing, and knew immediately that she wanted to study them in her 6th-grade science fair project. So Arrington went snorkeling with her father, a Ph.D. in fish ecology, who helped her capture six lionfish from the southern Indian River Lagoon.

She placed the six lionfish in separate tanks, with one as the control fish and five as experimental fish. To test their resilience to freshwater, Arrington first introduced her fish to saltwater with a salinity of 25 parts per thousand. Then, in order to lower the water salinity in her experimental tanks by 5 parts per thousand each day, she introduced freshwater with a salinity of less than one part per thousand. After eight days, the fish were thriving in nearly freshwater at a salinity of 6 parts per thousand.

The rules of the science fair disqualified participants whose test subjects died during experimentation, so to avoid the risk of killing the lionfish, Arrington stopped diluting the water. Still, she proved that lionfish could survive in low-salinity water, alerting scientists to be wary of the pervasive fish in freshwater areas.

Following the success of Arrington’s project, Craig Layman, an ecology professor at the University of North Carolina, confirmed her findings, acknowledging her in the peer-reviewed scientific journal Environmental Biology of Fishes.