Predicting algal blooms using eDNA

After starting her PhD studies in 2018, Monica Thukral would go for a swim off the coast of San Diego two to three times a week. The regular, physical connection with the waters helped to anchor her in her research at the University of California San Diego’s Scripps Institution of Oceanography. “I had an understanding of the physical processes: how the temperature and the wave energy change throughout the year,” Thukral recalls. “I was the first to know when an algae bloom was taking place.”In the laboratory, Thukral transformed that intuition into something more systematic. Using cutting-edge analytical tools, her team in the environmental systems biology lab of Andrew E. Allen—who also teaches at the nearby J. Craig Venter Institute, a genomics research foundation—strove to understand what was happening in the water on a molecular level. The scientists were working in the wake of a momentous oceanographic event. In 2015, a massive harmful algal bloom (HAB) had subsumed a stretch of Pacific coastline from southern California all the way to Alaska’s Aleutian Islands. It flooded the region’s waters with domoic acid, a neurotoxin so dangerous that it gives sea lions epilepsy; government regulators shuttered some commercial fisheries for months. Produced by microalgae—namely, several species of marine diatoms known as Pseudo-nitzschia—domoic acid can bioaccumulate in the marine food web, eventually getting consumed by humans, in whom it can cause nausea, cardiac arrhythmia, and a condition called amnesic shellfish poisoning, which can include memory loss and disorientation. Once the acid has accumulated in shellfish tissues