Volume of Oil Not Key Factor In Damage Done by Spill, Scientists Say

The Deepwater Horizon disaster is the largest oil spill in U.S. history, but it may not cause the most ecological damage if the oil can be kept out of the Gulf of Mexico’s fragile marshes, scientists say. While a projected 24 million to 52 million gallons of oil have gushed into the Gulf since the April rig blowout, analysts say the spill volume is less critical than the composition of the oil and the type of ecosystem it fouls. “Very large spills have had minimal impact and small spills have had a devastating impact,” said Judy McDowell, a senior scientist at the Woods Hole Oceanographic Institution. The 10.8 million gallons spilled during the 1989 Exxon Valdez disaster was a fraction of the 140 million gallons that spilled off Mexico’s Gulf Coast from the Ixtoc well in 1979. Yet while researchers found scant traces of the Ixtoc spill five years later, the Exxon Valdez spill is still affecting species. While the light crude from Ixtoc washed up on relatively lifeless beaches, the heavy crude from the Exxon Valdez coated highly productive marine habitats along rocky shores and broke down slowly because of the cold conditions. In the case of the latest Gulf spill, the depth of the spill will likely mean the toxic components of the oil may become greatly diluted before reaching the shore. But the unprecedented use of chemical dispersants in the Gulf could have a damaging impact on marine life.