Travels of sargassum seaweed explored

With the waves inside the 49-foot-long Air-Sea Interaction Saltwater Tank (ASIST) looking like small ripples rushing to a shoreline, University of Miami doctoral candidate Katie Simi stood on a small step ladder and dropped a clump of sargassum seaweed into the current. Just a few steps away, Maria Josefina Olascoaga, a professor of ocean sciences, recorded all the action with a high-definition camcorder, jotting down the speed of the brown macroalgae after it traversed the length of the tank. The whole process would be repeated more than a dozen times inside the Rosenstiel School of Marine, Atmospheric, and Earth Science's SUSTAIN Laboratory. While the experiment did not have the stunning visual effect of the simulated Category 5 hurricane conditions that are sometimes created in the tank's bigger brother-the 75-foot-long Surge-Structure-Atmosphere Interaction wind-wave tank-it was of profound importance. Using ASIST and other techniques, Olascoaga and team members from the Nonlinear Dynamics Laboratory are studying how the combined action of ocean currents, winds, and waves affects the transport of sargassum seaweed. Every year since 2011, the free-floating seaweed has inundated Caribbean, Gulf of Mexico, and Florida coastlines during the hot summer months, emitting toxic fumes and wreaking havoc on coastal ecosystems as it decays. "Understanding and learning more about its movement in order to predict where it will end up is challenging,” Olascoaga said.