BP spill damaged sea-floor life for 57 square miles, recovery may take decades or longer. By Ryan Gorman. dailymail.co.uk. September 25, 2013.

• Damage from the 2010 BP oil spill in the Gulf of Mexico extends almost 60-square-miles from the blown-out well
• The extent of damage was determined by taking sediment samples over a two month span in the months after the spill
• BP disputes the scientists’ claims, but does not dispute the extent of the damage caused by the disaster

Scientists believe it will be decades before the Gulf of Mexico sea floor, damaged across almost 60-square-miles, recovers from the 2010 BP oil spill, according to a recently published study.The most severe damage from the BP Deepwater Horizon disaster stretches almost two miles in all directions from the toxic spill, with moderate damage stretching 10.6 miles to the southwest and 5.3 miles to the northeast – a total of 57-square-miles.The study was conducted by a team of scientists from the National Oceanic and Atmospheric Agency, BP and multiple scholars. The findings were published last month in PLOS One, a scientific journal.Based on 68 sediment samples collected between one-third of a mile and 78 miles from the spill site in two surveys from September to October, 2010, the study is the first to attempt to quantify the extent of damage resulting from the blown-out Macondo well.‘Recovery rates in the deep sea are likely to be slow, on the order of decades or longer,’ the study said.As part of the research, bottom-dwelling organisms referred to as benthos were sifted from the collected sediment and tested for pollution. The sediment itself was also tested for toxins.Chemicals including barium, polycyclic aromatic hydrocarbons and total petroleum hydrocarbons were found to have permeated the sea floor, the study said. Barium is key component in the slurry often referred to as heavy mud, which is used to drill the well. The other chemical compounds are also known to be in the spilled oil, the study said.Mapping the concentrations of these chemicals found in the sediment enabled scientists to determine the oil spill’s foot print, as well as outline the severity of damage across the spill zone – while at the same time delineating damage caused by natural seepage.This data, in addition to the known differences in biodiversity found across different locations in the Gulf of Mexico, revealed a startling discovery – the more contaminated areas were far less diverse than non-polluted areas. 
‘It is apparent that the Deepwater Horizon blow out and subsequent oil spill did adversely affect deep-sea soft-sediment benthos,’ said the study.‘The tremendous biodiversity of meiofauna in the deep-sea area of the Gulf of Mexico we studied has been reduced dramatically,’ researcher Jeff Baguley, of the University of Nevada-Reno, told the New Orleans Times-Picayune.The floor-dwelling organisms scientists were studying are less than one-hundredth of an inch long.