More from the AP poll of scientists:
There is no comprehensive calculation for how much marshland was oiled, but estimates range from less than a square mile to just a handful of square miles. Regardless, in the big picture that's hardly alarming: Louisiana loses roughly 25 square miles of marsh each year due to a host of environmental and manmade causes. The state is the site of one of the most ferocious rates of land loss in the world.
Read the full AP report, and see an interesting information graphic on the story, at this link.