When oil leaks into the ocean, it gloms into a giant mass at the surface (think of the layers in a bottle of salad dressing). This is because oil is both hydrophobic—it doesn’t mix well with water—and lighter than water. With large quantities of oil, these properties make it difficult for microbes in the water to quickly and efficiently break down oil into less toxic forms. To aid the breakup of oil so that microbes can do their job, scientists decided to add a chemical to the spill that would break up the oil mass into tiny droplets. While this chemical dispersant helps expose more of the oil to bacteria and waves which help to break it down, it also makes the oil more available to the oysters.
And this is what Powers and his team determined. The addition of dispersant to the moderate salinity experiment tanks led to a drastic increase in oyster death. Mortality of oysters exposed to both oil and dispersant was about 90 percent, compared to 70 percent when only oil was added.
Okay now try it with horseradish.