作者：A. McDermott

In the clear shallows of Utah’s Virgin River, a slimy brown glob clings to thestreambed. Hannah Bonner stands shin-deep in the water, eyeing the goo. It lookslike Microcoleus, a toxic genus of cyanobacteria that was first detected in the riverfour years ago. Microcoleus doesn’t pose much risk underwater. Occasionally,though, a clump gets dislodged and floats to the surface, where a dog or child mighteat it. Ingesting even a tablespoon can deliver enough neurotoxin to kill a toddler.Bonner, an ecologist with the state’s division of water quality, hikes the rockybanks of the Virgin River regularly, surveying the riverbed for toxic cyanobacterialmats. When she finds a big one, Bonner asks any downstream waders to get outof the river, then walks over and stomps on the goo. Her heavy boots dislodge thecyanobacteria and break open its cells, releasing toxins and tissue into the water.Bonner dips a 5-gallon bucket into the churning soup and collects a sample, whichshe sends out to be tested for concentrations of several toxins, the deadliest ofwhich is anatoxin-a. The method mimics the worst-case exposure scenario, Bonnerexplains—a kid splashing and playing on the riverbank disturbs an area of mat andaccidentally takes a drink.

来源：PNAS .  2024 Vol. 121 Issue 2. DOI: 10.1073/pnas.2407913121