Animal counts in a surveyed area of the Gulf of Mexico’s ocean twilight zone fell steeply between surveys conducted after the 2010 Deepwater Horizon spill, according to a study described by Seth Borenstein of the Associated Press. From 2011 to 2015, fish counts dropped 63.5%, crustaceans 62% and larger animals, including squid and octopuses, 59.7% in the studied area.
Those comparisons start in 2011, not before the spill. The region had not been studied before 2010, lead author Tracey Sutton, a biological oceanographer at Nova Southeastern University, told the AP. Researchers used nets at different depths and acoustic sonar for the 2011 survey, then returned to the same place with the same equipment about three and a half years later. Their survey covered water from the surface to 5,000 feet.
Later sampling found that populations remained low, Borenstein reported. Sutton described a slight rise in 2022 and 2023, but said it was neither statistically significant nor lasting.
Sutton said temperature, oxygen supply and food did not vary with the decline, making the spill the most likely cause in his view. His team could not prove an exact causal link, the AP reported. Yale Environment 360 likewise reported that researchers called the spill “the most parsimonious explanation” while stopping short of concluding that it caused the declines.
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