In Kunming, China, 23 of the world's leading freshwater researchers gathered to map a battle plan against an invisible invader that has poisoned drinking water, shuttered beaches, and threatened economies across continents. George Bullerjahn, a microbiologist at Bowling Green State University who has studied freshwater microbes for more than three decades, was the only researcher from an Ohio university and one of only three from the entire United States invited to join this effort—a reflection of how central Ohio's own algal bloom crisis has become to global understanding of the problem.

The team's five-year plan, just published in Trends in Ecology & Evolution, emerged from a stark reality: toxic algal blooms are intensifying worldwide, happening more frequently and with greater intensity, appearing now in both temperate and tropical zones where they were once rare. In Ohio alone, the threat cuts deep. The 2014 Toledo water crisis, when cyanobacteria in Lake Erie produced microcystins that exceeded EPA safety limits and forced an entire city to drink bottled water, crystallized what scientists had long warned about. Today, toxic blooms threaten not just public health but also Ohio's water tourism industry, which generates billions in economic activity and supports hundreds of thousands of jobs. Globally, the stakes are even higher: in developing countries, contaminated water means not luxury lost but survival threatened—clean water access directly determines health, livelihoods, and whether communities can build stable economies.

The researchers, drawing from institutions in Denmark, Canada, Germany, China, South Korea, Austria, and New Zealand, identified four critical gaps in current research. First, they need to understand the specific drivers—chiefly nitrogen and phosphorus runoff from farmland and urban landscapes—that allow certain genetic strains of cyanobacteria to dominate and shift from harmless to deadly. Second, they're calling for more deployment of cutting-edge genetic tools to decode what happens inside these cells at the molecular level: what triggers them to start synthesizing toxins like microcystins in the first place? Third, the team recognized that harmful cyanobacteria never exist alone—they float alongside countless other microbial species whose interactions remain poorly understood. Mapping these relationships could reveal how blooms form, persist, decline, and become toxic. Fourth, researchers want to isolate how biological and physical factors—nutrient levels, temperature, light, zooplankton grazing, viral breakdown of cells—shape where and when blooms take hold.

A sobering gap cuts through all of this: tropical and subtropical regions, where climate change and development are fueling algal bloom growth, receive far less research attention and funding than temperate systems. In these warmer regions, blooms increasingly form on the lake bottom rather than the surface, making them harder to detect and study. This five-year plan, Bullerjahn said, represents "an amazing opportunity for students, faculty and the BGSU Center for Great Lakes and Watershed Studies to not only help lead the charge for meaningful research over the next five years, but also to create a lasting impact worldwide." What began as a local crisis in Toledo—a moment of visible, undeniable threat to millions of people—has become a catalyst for understanding a global phenomenon. The work ahead will determine whether science can transform that understanding into prevention.