Rapid decreases in salinity in any marine or even brackish water environment are going to have serious consequences for the fauna involved. Especially benthic organisms which cannot relocate like oysters and clams, and those which normally feed or spawn in shallower waters (crabs, many varieties of fish). While people get all up at arms over oil, fresh water introduced in massive quantities will kill everything caught in the low salinity zone, or organisms which wander in. I would wager plankton in the area are being destroyed wholesale, too, so every aspect of the food chain is being affected.
With all this talk about 'dead zones' offshore, the agencies involved are creating one, to the detriment of the fisheries industries there, the wildlife, the local economy, and the residents.
