<P> Most of the impact was on the marine species . Eight U.S. national parks were threatened and more than 400 species that live in the Gulf islands and marshlands are at risk, including the endangered Kemp's ridley turtle, the green turtle, the loggerhead turtle, the hawksbill turtle, and the leatherback turtle . In the national refuges most at risk, about 34,000 birds were counted, including gulls, pelicans, roseate spoonbills, egrets, terns, and blue herons . A comprehensive 2009 inventory of offshore Gulf species counted 15,700 . The area of the spill includes 8,332 species, including more than 1,200 fish, 200 birds, 1,400 molluscs, 1,500 crustaceans, 4 sea turtles, and 29 marine mammals . In a 2011 paper in the journal BioScience, researchers from the University of New Hampshire reported that the spill threatened 39 marine species in addition to the 14 currently under federal protection . Threatened species, the report found, ranged from' whale sharks to seagrass ". Also another impact to marine species was the impact to various food chains . With one break in the chain, the rest of the chain could be impacted greatly . </P> <P> Harry Roberts, a professor of Coastal Studies at Louisiana State University, has stated that 4 million barrels (640,000 m) of oil would be enough to "wipe out marine life deep at sea near the leak and elsewhere in the Gulf" as well as "along hundreds of miles of coastline ." Mak Saito, an Associate Scientist at Woods Hole Oceanographic Institution indicated that such an amount of oil "may alter the chemistry of the sea, with unforeseeable results ." Samantha Joye of the University of Georgia indicated that the oil could harm fish directly, and microbes used to consume the oil would reduce oxygen levels in the water . The ecosystem, she said, could require years or decades to recover, as with previous spills . Damage to the ocean floor would endanger the Louisiana pancake batfish in particular, whose range is entirely contained within the area affected by the spill . </P> <P> The actual number of mammal deaths due to the spill may be as much as 50 times higher than the number of recovered carcasses, according to a study published in the Journal Conservation Letters . "The Deepwater oil spill was the largest in US history, however, the recorded impact on wildlife was relatively low, leading to suggestions that the environmental damage of the disaster was actually modest . This is because reports have implied that the number of carcasses recovered...equals the number of animals killed by the spill" stated Rob Williams from University of British Columbia . </P> <P> On 22 October 2010, it was reported that miles - long strings of weathered oil had been sighted moving toward marshes on the Mississippi River delta . Hundreds of thousands of migrating ducks and geese spend the winter in this delta . Two years after the Deepwater explosion, migratory birds were found to have carried chemicals from the spill to Minnesota . Preliminary evidence showed the vast majority of the small sample of pelican eggs tested contained "petroleum compounds and Corexit". As of 2 November 2010, 6,814 dead animals had been collected, including 6,104 birds, 609 sea turtles, 100 dolphins and other mammals, and 1 other reptile . According to the U.S. Fish and Wildlife Service, cause of death had not been determined as of late June . According to NOAA, since 1 January 2011, 67 dead dolphins had been found in the area affected by the spill, with 35 of them premature or newborn calves . </P>

Who was affected by the deepwater horizon oil spill