We hear a lot about the immediate effects of a major oil spill, but what happens later? Our guest Dr. Jeffrey Short is a biochemist who has investigated ecosystem effects of major spills. Working with our host Dr. Robert Spies after the 1989 Exxon Valdez disaster, he discovered that large quantities of oil persisted in the subsurface long after the spill - a finding that was quite controversial at the time. More recently he came out of retirement to work on assessing the damage from the 2010 Deepwater Horizon spill, where he showed that the official estimates of bird mortality were at least an order of magnitude too low. That mortality in turn caused a dramatic population increase in Menhaden, the key link in the Gulf of Mexico food chain and the second-largest commercial fishery in the US. The population explosion has led to malnourishment and greatly decreased the economic value of the fishery, as well as its ecosystem function.