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B y A l e x a n d r a B e c k e r What health risks does syn t hetic debris pose? Samples from a water column Tucked into the shoreline between Santa Cruz and Carmel-by-the-Sea is Monterey Bay Aquarium Research Institute (MBARI), a private organization dedicated to developing technology for oceanographic study. Built near the inland center of the bay itself, the Institute sits at the head of the Monterey Canyon—a steep, underwa- ter drop with depths comparable to the Grand Canyon. It is one of the deepest submarine gorges along the continental United States and home to a large and diverse body of marine life—and its proximity to land offers a unique opportunity to study the deep ocean. Often called the "final frontier" on planet Earth, the deep ocean remains widely unexplored. But according to recent findings from scientists at MBARI, even the bottom of the sea isn't immune to human pollution. What's more—it's ending up in our food supply. Using innovative robotic technology developed by MBARI, researchers gathered samples of a "water column" from the surface all the way down to the bottom of the sea floor. After filtering the samples with a tech- nique called Raman spectroscopy, which uses a laser to measure the scattering of light by matter, they discovered that microplastics were present throughout the ocean. "Every sample we had, there was plastic in it," said Kyle Van Houtan, Ph.D., chief scientist at the Monterey Bay Aquarium and one of the researchers who teamed up with MBARI for the study. "There was actually four times as much plastic below the surface as there was at the surface." While plastic itself does not easily degrade, it will break into increasingly smaller pieces. Once these tiny pieces are covered in algae and other biological mate- rials, their buoyancy properties change, which explains their presence throughout the water samples, Van Houtan said. This research was the first time this kind of microplastic sampling had been done on a vertical transect of the ocean—rather than across a large swath of the surface. ➟ 29 t m c » p u l s e | n o v e m b e r 2 0 1 9