What the Spill Will Kill: Begley runs down the damage to the Gulf ecosystem: 

It is increasingly clear that the initial reports of undersea oil were right, that life-giving oxygen in the water column is indeed being depleted, and that unless the laws of chemistry have been repealed, dispersants are likely worsening the tentacles of undersea crude. What might have been just another oil spill—albeit a bad one—has been transformed into something unprecedented. Even if the containment dome lowered into place late last week continues to siphon off some of the leaking crude, the Deepwater Horizon disaster will enter the record books not for how much but for where: an enormous release of crude oil not only onto vulnerable shorelines and fragile marshes but into the largely unexplored depths of the sea. The consequences for the delicate balance of existence in the vulnerable ecosystems of the gulf, and for the vast cycles of nature that sustain life there and beyond, are as incalculable as they are potentially devastating.