In an informal AP survey, 35 researchers who study the Gulf lowered their rating of its ecological health by several points.
On a scale of 0 to 100, the overall average grade was 65, down from 71 before the spill.
This reflects scientists' views that the spilled oil further eroded a beleaguered body of water tainted for years by farm runoff, overfishing, oil from smaller spills and natural seepage.
Scientists and the government are shifting their focus from the surface to deeper waters and the ocean bottom.
They say they're worried the oil deep below will cause genetic mutations, stress or weaken some species, with unknown or delayed effects.