It appears that abnormally low dissolved oxygen levels are not being created by bacteria using the oil/dispersant mix as a food source. This information is being viewed by some as evidence that using dispersants was the right choice.

However, I think it’s too soon to tell if this is good news, because, for example,  toxicity effects of the oil/dispersant mixtures are not yet fully known.

Fish need at least 4 milligrams per liter of oxygen to survive, so if low dissolved oxygen levels were a widespread problem, we might see fish kills, although fish could simply avoid low-dissolved oxygen zones if they have room to maneuver.