In the oil spill zone in the Gulf of Mexico scientists found sick dolphins as well as deep-water corals. Poor health has been identified because of the polluted water in both the dolphins and coral reefs. There, an oil spill occurred two years ago, the worst off-shore oil spill in the history of the US. The dolphins are suffering from low weight, anemia, low blood sugar, and symptoms that indicate liver and lung disease. In 2011 32 dolphins were tested, half of which had low levels of certain hormones that help respond to stress, metabolism, and immune function. One of the examined dolphins has already died and the rest are at risk of dying. As for the corals, corals 11km from where spill occurred were found covered in a mucus-like substance and showing signs of tissue damage and severe stress. The corals 20 km from the site were fine.