Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. New Study: Oil from Gulf Spill Settling on Sea Floor Researchers say oil from leak appears to have seeped into underwater canyon east of ruptured BP well, where they say it is killing small plants and bacteria VOA News 17 August 2010 A pelican flies over new marsh grass in an area that had been impacted by the oil from the Deepwater Horizon oil spill near East Grand Terre Island, Louisiana, 10 Aug. 2010 Photo: AP A pelican flies over new marsh grass in an area that had been impacted by the oil from the Deepwater Horizon oil spill near East Grand Terre Island, where the Gulf of Mexico meets Barataria Bay along the Louisiana coast, 10 Aug. 2010 A new study by scientists in the Gulf of Mexico finds that oil from the worst offshore oil spill in history is settling on the sea floor, where it is harming critical microscopic organisms. Researchers at the University of South Florida issued the report on the impact of the BP oil spill Tuesday.  They said oil from the leak appears to have seeped into an underwater canyon east of the ruptured BP well, where they say it is killing small plants and bacteria. The plants, called phytoplankton, are a critical part of the food chain for several species of fish. On Monday, a team of scientists at the University of Georgia said a review of government data showed that almost 80 percent of the oil from the BP leak remains in the Gulf - much higher than government estimates. U.S. officials have said that only about a quarter of the spilled crude remains in the water. The commercial shrimping season opened Monday in the Gulf state of Louisiana. The Associated Press said many shrimpers reported large catches that were free of oil. Also Monday, the U.S. Interior Department said it is toughening environmental reviews for all new deepwater oil drilling. Oil first began gushing into the Gulf of Mexico after an April 20 explosion on a BP well that killed 11 workers. BP capped the well in mid-July and the British-based company has been engaged in a massive clean-up effort. Some information for this report was provided by AP and Bloomberg. .