A recent study has shown nearly half the bottlenose dolphins living in Barataria Bay in the Gulf of Mexico, the area oiled by the explosion of the Deepwater Horizon oil rig four years ago, were/are in guarded or worse condition.

While a dolphin is examined, one researcher is told to watch its eye to make sure the mammal stays alert and interested in what’s going on as a way to monitor its vitals during the study. (Photo: Ted Jackson/The Times Picayune)

Twenty-five percent were significantly underweight. Seventeen-percent were classified as being in poor or grave condition and not expected to survive.

Oiled dolphin, summer 2010, in Barataria Bay, La. (Photo: Louisiana Department of Wildlife and Fisheries/Mandy Tumlin)

The findings showed unusual lung damage and very low levels of adrenal hormones, which are critical for responding to stress.

The abnormalities were not found in bottlenose dolphins tested in Sarasota Bay, Fla., chosen as a comparison site because it was not contaminated with oil.

Research study, Barataria Bay, August 15, 2011. (Photo: Ted Jackson/The Times Picayune)

The explosion 40 miles off the Louisiana coast spewed over 4 million barrels of oil into the sea, spreading an oil slick across open water that covered more than 1,000 miles of coastline

The research team, composed of government, academic and non-governmental researchers, concluded that the symptoms were consistent with petro-carbon or fuel-oil contamination, and that the evidence supports exposure to the BP oil, and not to other chemicals or natural illnesses.

British Petroleum, who owned the rig, funded the study and had personnel present while the animals were examined, disputed the findings.