BP oil disaster scientists say Gulf of Mexico is almost back to pre-spill health levels...so why are a huge number of dolphins and turtles dying?

One year on from the BP oil spill and some scientists are declaring the overall 'health' of the Gulf of Mexico as back to normal.

More than three dozen scientists now grade the Gulf's health a 68 on average, using a 1-to-100 scale. This is just below the 71 grade the same researchers last summer said they would give the ecosystem before the spill.

However the scientists are also warning that just because the surface of the water looks clear, beneath is still a mess.

They cite significant declines in key health indicators such as the sea floor, dolphins and oysters. In interviews, dozens of Gulf experts emphasised their concerns, pointing to the mysterious deaths of hundreds of young dolphins and turtles, strangely stained crabs and dead patches on the sea floor.

Jane Lubchenco, head of the National Oceanic and Atmospheric Administration, said the Gulf is 'much better than people feared, but the jury is out about what the end result will be.

'It's premature to conclude that things are good. There are surprises coming up - we're finding dead baby dolphins,' she said.

Just as it was before the April 20 accident when the Deepwater Horizon oil rig exploded, spewing 172million gallons of oil, the Gulf continues to be a place of contradictions.

The surface looks as if nothing ever happened while potentially big problems are hidden deep below the surface, in hard-to-get-to marshes and in the slow-moving food web. Some may not even be known for years. Read More