Following the Deepwater Horizon explosion and spill in 2010, BP used more than 1.8 million gallons of chemical dispersants in an effort to break up the oil. The dispersants also wiped out plankton, according to a new study.

From the Associated Press:

For the study, Alabama researchers pumped water from Mobile Bay into 53-gallon drums, then added oil, dispersant or both in proportions found during the oil spill to simulate the spill’s effects on microscopic water-life in the bay. …

The researchers found that, within days, the numbers of plant-like phytoplankton and ciliates — plankton that use hairlike cilia to move — increased under an oil slick. But they dropped significantly in the drums with dispersant or dispersed oil, while the numbers of bacteria increased. …