Among the afflictions found in the Louisiana dolphins were severe lung disease and deficient levels of adrenal stress-response hormones. A quarter of the Louisiana dolphins were also underweight. The researchers said that many disease conditions seen in the Barataria Bay dolphins are rare but consistent with oil exposure and toxicity.
The research is among the strongest evidence yet to link the oil spill to sick dolphins.
Record Dolphin, Sea Turtle Deaths Since Gulf Spill
"I've never seen such a high prevalence of very sick animals - and with unusual conditions such as the adrenal hormone abnormalities," lead author Dr. Lori Schwacke, a chief with NOAA Centers for Coastal and Ocean Sciences, said in a NOAA press release.
BP financed the study but is disputing its finding. A BP spokesman told the Wall Street Journal that NOAA "still hasn't provided BP with any data demonstrating that the alleged poor health of any dolphins was caused by oil exposure."
NOAA researchers acknowledge in the study that dolphin deaths had been occurring in the region since February 2010 -- with at least 1,050 marine animal strandings documented before the spill. Schwacke and the others wrote they "cannot dismiss the possibility that other pre-existing environmental stressors made this population particularly vulnerable to effects from the oil spill."