Research team uses 6-foot-long ‘test tubes’ to study red tide

A potential treatment for Florida’s devastating red tides has taken another step toward widespread development after successful trials in Sarasota Bay.

Additional detailed data analysis is needed to confirm the results, but UCF Assistant Professor of Biology Kristy Lewis is encouraged by the large-scale testing of a red tide mitigation technology called clay flocculation conducted in collaboration with the Mote Marine Laboratory.

This study is the first successful test of any red tide mitigation technology in open water using large water column containers called limnocorrals. These tubes—about six feet in diameter—extend from the water’s surface to the ocean floor, allowing scientists to test real-world ocean conditions in a controlled environment. Think of it like a giant test tube.

Specialists and technicians from Mote Marine Laboratory provided the necessary resources to place eight limnocorrals in Sarasota Bay. Four columns were treated with a fine spray of the clay solution, while the other four served as a control.

Clay flocculation works with the clay that clings to the Karenia brevis algae, responsible for Florida’s red tide, and sinks them to the ocean floor. Lewis has spent the past three years carefully testing the impact of introducing this non-native mineral into the ocean ecosystem. It not only looks for changes in nutrients and water quality, but also assesses how clay affects the health of invertebrates such as blue crabs, sea urchins and clams.

“We want to make sure the cure is not worse than the disease,” he says.

The original plans for the large-scale test were simply to measure the effect of the clay on the ecosystem, but the unexpected appearance of a real red tide phenomenon increased the realism of the experiment. Initial results indicate the clay performed as expected, but the question remains whether the algae’s toxins remain dormant or active on the ocean floor. The water samples collected during the experiment should provide an answer.

The tests are the latest in a long chain of progressively larger-scale experiments — from tiny test tubes to 5-gallon tanks and 300-gallon replicas of Sarasota Bay. The next steps depend on the outcome of the test results, but there are already plans to investigate what happens to the clay-coated algae when they are used near seagrasses and then distributed by tides and currents.

More than a dozen people were involved in setting up and running the experiment over the course of four days, including Emily Hall, co-investigator on the grant and senior scientist and program manager from Mote Marine Laboratory. Lewis also credits UCF assistant professors of biology Michelle Gaither and Robert Fitak for providing the necessary techniques and equipment to conduct the experiment. PhD student John Kristoffer “JK” Andres will analyze the results of this experiment as part of his dissertation research.

Visiting Sarasota, Florida, in the midst of a red tide event, reminded Lewis how critical research is to restoring the state’s coastal health and the corresponding impact on its economy. Lewis says she’s ready to go another three years if that’s what it takes to find a definitive solution to red tide.

“I want to take every precaution and do our due diligence to make sure we’re not doing more harm than good,” he says. “When it comes time to convince the policy makers and the people who can take action, we will be prepared.”

The work is the next step in Lewis’ research into finding a method to combat red tide.