Efforts to reduce the amount of phosphorus and other nutrients washing off farm fields and into Lake Erie shifted into overdrive after high levels of a bacterial toxin shut down the drinking water supply to more than 400,000 Toledo-area residents last August. “We know what causes these blooms: It’s nutrients from farm runoff. What we don’t fully understand is what determines whether these cyanobacterial blooms are highly toxic or not,” said a marine microbiologist and oceanographer and leader of this project.