U.S.-based marine scientists say bottlenose dolphins and deep-sea corals in the northern Gulf of Mexico, where the massive Deepwater Horizon oil spill occurred two years ago this April, are showing signs of severe stress from their prolonged exposure to the polluted water.

The dolphins' ailments include low body weight, anemia, low blood sugar, and symptoms of liver and lung disease, according to biologists working on a post-spill, natural resource health assessment for NOAA, the U.S. National Oceanic and Atmospheric Administration. They report that nearly half of the dolphins they tested in the summer of 2011 have abnormally low levels of the hormones that help with stress response, metabolism and immune function.    

The scientists physically examined 32 live dolphins in the Gulf's Barataria Bay.  One of the aquatic mammals was found dead this past January.  The researchers fear more of the dolphins will die of illnesses related to the 2010 oil spill, the worst offshore oil spill in U.S. history.  During the accident, a damaged British Petroleum well, located on the seabed 80 kilometers off the Louisiana coast, gushed nearly five million barrels of crude oil into Gulf waters before being capped.

Another new NOAA study identifies the BP spill as the source of the contamination that is slowly killing numerous colonies of deep-water corals.  A detailed chemical analysis found a match between oil from the ruptured seafloor well and oil found coating colonies of slowly dying corals, 11 kilometers from the spill site.

The corals the scientists examined were covered in a fluffy, brown, mucus-like substance, and showed signs of tissue damage and severe stress.  

The marine biologists note that in 10 years of research in the Gulf of Mexico, they have never seen deep-water coral dying in this manner.  

Deep-water coral species usually are not harmed in an oil spill, but not even creatures living at depths of more than 1,200 meters were spared the unprecedented magnitude of the BP oil disaster.  However, the scientists say communities of deep-water corals 20 kilometers from the ruptured oil well were clean and thriving.  

NOAA released the preliminary results of the dolphin study on Monday.

The study of the deep-water corals is published in the journal, Proceedings of the National Academy of Sciences.

The Deepwater Horizon oil spill was an environmental and economic catastrophe.  Not only did it kill or threaten the region's vast assortment of flora and wildlife, but the disaster also devastated the livelihoods of many thousands of people who work in fisheries and other businesses dependent on Gulf of Mexico resources.

Some information for this report was provided by AP and AFP.